NISTIR 6618 and NTIA SP-04-416

Significant Papers from the First 

50 Years of the Boulder Labs 

Edited by

M.E. DeWeese

M.A. Luebs

H.L. McCullough
NISTIR 6618

and

NTIA SP-04-416

Significant Papers from the First 

50 Years of the Boulder Labs 

Edited by

M.E. DeWeese, NIST

M.A. Luebs, NTIA

H.L. McCullough, NOAA

Sponsored by

National Institute of Standards and Technology

National Telecommunications and Information Administration

National Oceanic and Atmospheric Administration

Boulder, Colorado

August 2004

ii

U.S. Department of Commerce

Donald L. Evans, Secretary

National Institute of Standards and Technology

Arden L. Bement, Jr., Director

National Oceanic and Atmospheric Administration

Conrad C. Lautenbacher, Jr., Undersecretary of Commerce for Oceans and Atmosphere

 and NOAA Administrator

National Telecommunications and Information Administration

Michael D. Gallagher, Assistant Secretary for Communications and Information
Acronym Definitions 

CEL Cryogenic Engineering Laboratory

CIRES Cooperative Institute for Research in Environmental Sciences

CRPL Central Radio Propagation Laboratory 

CU University of Colorado 

DOC Department of Commerce 

EDS Environmental Data Service 

ERL ESSA Research Laboratory 

ESSA Environmental Science Services Administration

ITS Institute for Telecommunication Sciences 

ITSA Institute for Telecommunication Sciences and Aeronomy 

JILA Joint Institute for Laboratory Astrophysics 

NBS National Bureau of Standards 

NCDC National Climatic Data Center 

NGDC National Geophysical Data Center 

NIST National Institute of Standards and Technology

NOAA National Oceanic and Atmospheric Administration 

NTIA National Telecommunications and Information Administration 

OAR Office of Oceanic and Atmospheric Research 

OT Office of Telecommunications 

OTP Office of Telecommunications Policy 

RSMS Radio Spectrum Measurement System 

SEC Space Environment Center 

ii
Contents

Page

Acronym Definitions ....................................................................................................... ii 

Historical Publications Committee .................................................................................. iv 

Introduction ..................................................................................................................... 1 

Historical Overview of the Federal Laboratories in Boulder .......................................... 2 

Historical Timeline ......................................................................................................... 5

Papers from the 1950s...................................................................................................... 9 

Papers from the 1960s...................................................................................................... 17 

Papers from the 1970s...................................................................................................... 39 

Papers from the 1980s...................................................................................................... 77 

Papers from the 1990s...................................................................................................... 119

Papers from the 2000s...................................................................................................... 159

Author Index .................................................................................................................... 173 

Subject Index ................................................................................................................... 177 

iii
Boulder Labs 50th Anniversary 

Historical Publications Committee

Chair: Edie DeWeese, NIST 

Debe Daily-Fisher, NOAA 

Evie Gray, NTIA/ITS 

Carol Knight, NOAA 

Margaret Luebs, NTIA/ITS 

Heather McCullough, NOAA 

Kate Remley, NIST 

iv
Introduction 

The Department of Commerce Boulder Labs were dedicated on September 14, 1954, in the 

shadow of World War II, and at the dawn of a bright future. This volume presents a snapshot of 

our research accomplishments in the half century since then. During this time, the Boulder Labs 

have evolved from the National Bureau of Standards’ Central Radio Propagation Laboratory to 

today’s National Institute of Standards and Technology, National Oceanic and Atmospheric 

Administration, and National Telecommunications and Information Administration’s Institute 

for Telecommunication Sciences. The papers we have collected represent the most significant 

work of all the agencies of the Boulder Labs, whatever their name at the time of publication. 

The past 50 years have been productive ones at the Boulder Labs. As you look through this 

collection of significant papers, think about the countless hours of work that brought them to 

being. Think, too, about the papers behind the papers: the works that provided the building 

blocks of the research represented here. Finally, think about the individual efforts of the staff 

members whose dedication has contributed so much to our community, the nation, and the 

world. 

Edie DeWeese, Chair 

Historical Publications Committee 

Boulder, Colorado 

September 2004 

1
Historical Overview of the Federal Laboratories in Boulder 

In 1902, when Guglielmo Marconi observed from the SS Philadelphia that radio waves could be 

received at much greater distances at night than during the day, the foundation of a long history 

of joint radio and atmospheric research was laid. This interaction of research had ramifications 

for Boulder in the years to come. 

Just months before Marconi realized this diurnal effect out in the Atlantic, the National Bureau 

of Standards (NBS) was established in Washington, DC, on March 3, 1901. Its mission was to 

establish the standards of measurement for the purposes of commerce. The Radio Laboratory 

Section was formed in 1913 and designated as Section 6 of the Electricity Division of NBS. This 

section moved to its new facility in October of 1918 far out on Connecticut Avenue in Northwest 

Washington, where it would remain until 1954. 

On May 1, 1946, the Radio Laboratory Section was established as its own division within NBS 

and named the Central Radio Propagation Laboratory (CRPL). On that same day the Radio 

Propagation Executive Council held its first meeting and discussed the inadequate space 

available at the dated Connecticut Avenue campus. A new larger facility to house the new 

division was proposed at this location; however, CRPL staff realized that a new facility also 

required a quiet environment relatively free of radio interference. The existing campus could not 

provide such an environment. 

In January of 1947, funding was approved for a new CRPL building at the NW Washington site 

with construction to begin in 1948. However, construction was postponed to consider a 

consolidated facility outside the Washington area. This site should accommodate the division as 

well as the test and field site, and ideally located near a suitable university with a relatively quiet

radio environment. When President Truman issued a confidential policy in early 1949 directing 

that no more major government buildings be constructed in the District of Columbia, the search 

for a new location was on. This effort to decentralize the Federal government was a result of 

early cold war concerns of nuclear attacks on Washington. 

In June of 1949, the director of NBS, Dr. Edward U. Condon, attended the Echo Lake Cosmic 

Ray Symposium at Mount Evans near Idaho Springs. Present at the Symposium was Dr. Walter 

Orr Roberts, Superintendent of the High Altitude Observatory, University of Colorado at Climax 

Springs. Dr. Roberts invited Dr. Condon to visit Boulder that weekend and take a tour of the CU 

campus. Dr. Roberts was convinced that Boulder was the ideal location for the new CRPL 

laboratory. Dr. Condon agreed and returned with several members of the CRPL staff to enjoy the 

4th of July holiday in Boulder. 

The 81st Congress had authorized only $4,475,000 in funding for the construction of the new 

radio laboratory. No appropriations were slated for the purchase of property. At the time, 

Charlottesvi1le, Virginia, and Palo Alto, California, were under serious consideration for the 

location of the new laboratory because they had viable locations and land available. The Boulder 

Chamber of Commerce made a move to enter the competition. Led by its President, Vergyl H. 

2
Reynolds, and Junior Past President, John F. Allardice, the Chamber created the Standards 

Committee on February 27, 1950, in order to raise funds to purchase land. Two tracts of land 

totaling 217 acres were available south of town that could be obtained for approximately 

$70,000. The land was situated west of Marshall Road (now South Broadway) and south of 

Green Mountain Cemetery. 

On March 2, James J. Yeager, a Boulder businessman, accepted chairmanship of the campaign. 

By early April, Yeager had a large group of Boulder citizens organized for the Boulder Chamber 

of Commerce–U.S. Bureau of Standards Radio Laboratory Fund Campaign. The campaign 

officially kicked off at 7:30 a.m. on April 1 at a breakfast addressed by Elmore Peterson, Dean of 

the Business School. A short two weeks later, over $90,000 was collected and the campaign was 

over. The largest contribution, totaling $10,000, came from the Boulder Elks Lodge No. 566. All 

contributions of $100 or more were recognized by public announcement and later by inscription 

on a metal plaque that was placed in the lobby entrance. The final negotiated price for the land 

was $63,000, with the excess money used to purchase land east of town on Arapahoe Road. 

(This tract of land was known as the Boulder Industrial Park and was later occupied by the Ball 

Brothers Research Corporation.) On June 13, 1950, the deed to the land was transferred by the 

Boulder Chamber of Commerce to the United States of America. 

The architectural firm of Pereira, Luckman, and Stanton was chosen to design the Radio building 

for the new property. This firm subsequently won the 1954 Award of Merit from the American 

Institute of Architects for their design. However, before construction of the Radio laboratory 

began, another important construction project began on the newly acquired property. On August 

29, 1949, the Soviet Union detonated that country’s first atomic bomb. The United States’ 

response to this development was to accelerate research for the production of the super bomb, or 

hydrogen bomb. Initial designs called for copious amounts of liquefied hydrogen. No large 

liquifier facilities existed this side of the Mississippi, and none could supply the amounts 

required. Therefore, on March 28, 1951, it was announced that a large hydrogen liquefying plant 

would be constructed at the Boulder site. Construction was completed in a little over a year, an 

incredible feat of engineering. The new Cryogenic Engineering Laboratory was capable of 

producing 350 liters of liquid hydrogen an hour, and supplied the liquid used in the world’s first 

hydrogen bomb. This bomb, code named Mike, was exploded on November 1, 1952, at Elugelab 

Island in the South Pacific. Part of the original building is still in use today, although subsequent 

hydrogen bomb tests did not require large amounts of liquid hydrogen. 

About the time these large construction projects began, NBS negotiated for a temporary facility 

in Boulder. The Colorado National Guard Armory on Foothills Road (now North Broadway) was 

transferred to the CRPL. The staff would remain for over three years as the Radio building was 

constructed. The Radio building was constructed by the Olson Construction Company of Denver 

for $3,920,000. Only four of the present six wings were built, for a gross area of approximately 

172,800 square feet. The building was completed in March of 1954 with the people and 

equipment from the Armory site moving in April. By the time the dedication ceremonies were 

held in September, over 512 metric tons of equipment and over 450 people had moved to 

Boulder from Washington. The majority of the move was conducted in July during a recordbreaking heat wave of 104 oF in Boulder and up to 118 oF on the route across the mid-west. 

3
On September 14, 1954, President Eisenhower, the first incumbent President ever to visit 

Boulder, led the dedication ceremonies. With area schools called off, an estimated crowd of 

10,000 citizens and dignitaries attended the ceremonies. Eisenhower declared “...it is my 

privilege to dedicate this facility of the National Bureau of Standards to the welfare of

humanity—in America and throughout the world.” With that he pushed a button and unveiled the 

metal plaque with the names of the Boulder contributors. Also unveiled was a slab of granite 

with the names of the architects and builders. Sealed behind the granite slab is a container with 

15 important documents published by NBS. 

Several more buildings were constructed in the sixties on the Bureau campus. All of the roads on

the site were named after Nobel Prize winners in Physics. The roster of names included: 

Anderson, Appleton, Compton, Curie, Lawrence, Marconi, Millikan, and Wilson. Also 

constructed was the Joint Institute for Laboratory Astrophysics (JILA) building on the CU 

campus. JILA is a cooperative research facility between NIST and the University of Colorado, an 

association that produced its own Nobel Prize for Physics in 2001. 

In the early sixties NBS acquired 1800 acres of land north of Boulder known as Table Mountain. 

With its large flat terrain, this site is still used as a radio field and test site. Other sites were also 

established at this time, including a 20 kHz transmission site near the town of Sunset in Four 

Mile Canyon, an observation facility at Fritz Peak south of Rollinsville, and the WWV/WWVB 

broadcast site north of Ft. Collins. 

On October 11, 1965, the Central Radio Propagation Laboratory was transferred from NBS to 

the United States Weather Bureau and became the Environmental Science Services 

Administration (ESSA), Institute for Telecommunication Sciences and Aeronomy (ITSA). With 

that transfer, the Boulder Laboratories, National Bureau of Standards was renamed the Boulder 

Laboratories, United States Department of Commerce. The ESSA Research Laboratory (ERL ) 

was created and with no facilities available, space was leased from CU. 

On October 3, 1970, ESSA was renamed the National Oceanic and Atmospheric Administration 

(NOAA). This consolidated several groups into one agency to provide atmospheric, marine and 

oceanic services. In 1978 ITS joined NTIA, and on August 23, 1988 the National Bureau of 

Standards was renamed the National Institute of Standards and Technology (NIST). Through the 

years, these agencies have continued to grow and expand. On October 18 of 1996, ground was 

broken for a new NOAA building on the south part of the original 217-acre site that the citizens 

of Boulder had purchased 47 years before. Construction began on November 18, 1996, and the 

facility was dedicated on November 20, 1998. This facility houses 236,000 square feet of office 

and laboratory space at an estimated cost of $56 million. The NOAA building consolidates the 

facilities that had been spread out around Boulder. 

4
Boulder Labs Timeline 

1946: Central Radio Propagation Lab is organized to direct research and predictions in the field of 

radio wave propagation, including investigation of solar and geophysical effects on radio 

communication, and research on the upper atmosphere. 

1950: In only two weeks, the people of Boulder raised $90,000 to buy the 217 acres of land 

the Boulder Labs now occupies. This land donation was an important factor in the choice of 

Boulder for the Labs, along with its varied terrain, freedom from radio interference, and 

proximity to the University of Colorado. 

1951: The first building is constructed—not to house radio research, but to serve as the world=s 

largest cryogenic facility, able to produce up to 320 liters of liquid hydrogen per hour. 

1951: The first CRPL staff were transferred to Boulder to work in the Colorado National Guard 

armory on North Broadway while construction was underway at the 325 Broadway site. 

1954: On September 14th, President Dwight D. Eisenhower, the first incumbent President ever to visit 

Boulder, arrives to dedicate the Boulder Laboratories. 

1954: The Bureau=s first atomic clock, NBS-1, is built in Washington and shipped to Boulder. Using 

the oscillation of cesium atoms, it sets a new standard for the second, so accurate it lost only one 

second every 300 years. 

1954–1965: CRPL develops worldwide ionospheric soundings, used to predict high-frequency usable

frequencies for radio services, very low frequency (VLF) transmissions for reliable communication 

and navigation, as well as developing very high frequency (VHF) ionospheric scatter systems for 

transoceanic and Arctic links. 

1956: Boulder’s World Data Center system is established to collect, archive, and distribute 

crucial data for the first International Geophysical Year in 1957. 

1957: Modern data record of atmospheric CO2, a major greenhouse gas, begins at Mauna Loa 

Observatory in Hawaii; measurements continue today under NOAA=s Climate Monitoring and 

Diagnostics Laboratory. 

1960s: ITSA’s propagation research in the millimeter-wave bands (20 GHz and above) produces a 

body of knowledge now being used by new commercial wireless systems. 

1962: A pulsed ruby laser is built by NBS’s Donald Jennings, making possible Apollo 11’s famous 

laser experiment measuring the Moon=s distance from Earth. 

1965: In 1965, CRPL is transferred from NBS to the newly formed Environmental Science Services 

Administration (ESSA), and renamed the Institute for Telecommunication Sciences and Aeronomy

(ITSA). 

5
1965: Environmental Science Services Administration (ESSA), NOAA’s forerunner, is created to 

encompass the Weather Bureau, Coast and Geodetic Survey, and the Central Radio Propagation Lab, 

now reorganized to form the Aeronomy Division, forerunner of NOAA>s Aeronomy Laboratory, and 

the Space Environmental Forecasting Division, forerunner of NOAA=s Space Environment Center. 

1965: Institutes for Environmental Research established in ESSA to study atmospheric 

sciences, oceanography and earth sciences. The Institutes, predecessor of NOAA=s 

Environmental Research Laboratories (ERL), are headquartered in Boulder. 

1965: Environmental Data Service (EDS) formed within ESSA includes National 

Geophysical Data Center (NGDC), which collects, organizes, and disseminates data on the 

Earth and its systems, and continues under NOAA today. 

1965: Space Disturbance Forecast Center begins routine forecasting service with USAF Air 

Weather Service, a relationships that continues today.

1965: Carl Disch, a Boulder Labs employee, disappears from an Ionosphere-Forward Scatter 

station in Byrd, Antarctica. He apparently missed a hand line during high winds and was 

never seen again. 

1967: The new Joint Institute for Laboratory Astrophysics, JILA, is dedicated on the University of 

Colorado campus in Boulder. This opens up research projects in astrophysics, atomic physics, and 

aerodynamics, and is a cooperative effort between NIST and CU. 

1967: NBS staff redefine the second, which had been based on a fraction of the mean solar day, as 

“the duration of 9,192,631,770 periods of radiation corresponding to the transition between the two 

nuclear hyperfine levels of the fundamental state of the atom of cesium 133.” 

1967: ITSA is split into four entities within ESSA, with three laboratories oriented toward 

environmental science issues, and the new Institute for Telecommunication Sciences (ITS) focused 

exclusively on telecommunications. 

1967: NOAA=s first joint institute, the Cooperative Institute for Research in Environmental Sciences, 

established at the University of Colorado to partner with the local labs in areas of atmospheric 

research. 

1968: NIST scientists develop slush hydrogen, a promising and desirable rocket fuel. 

1969: Apollo 11 leaves reflectors on the moon in order to more accurately measure the distance 

between Earth and the moon. JILA scientist James Faller suggested the idea, and NBS was able to 

accurately measure the distance to within 2.5 cm. The reflectors are still used today to test 

gravitational and mass theories. 

1972: NBS TvTime is demonstrated to show how subtitling can benefit the hearing impaired. It is 

later approved for mass use by the Federal Communications Commission and NBS wins an Emmy

Award in 1980 for excellence in engineering. The NBS staff responsible for the work (Dick Davis, 

Jim Jespersen, and George Kamas) were invited to the White House to receive President Carter’s 

congratulations.

6
1972: Ken Evenson and his team are entered in The Guinness Book of World Records for measuring 

the frequency of laser light. It leads to a new definition of the meter that is 100 times more accurate 

than the previous standard. 

1973: ITS designs the Radio Spectrum Measurement System (RSMS), a state-of-the-art computercontrolled measurement system in a mobile van. 

1975: Aeronomy Lab develops the first Doppler radar wind profiler, located near the town of Sunset 

in the Boulder front range, for the measurement of winds up to 10 kilometers away. The Sunset radar 

pioneered wind-profiling technology that later involves other Boulder labs and results in 

improvements to daily weather forecasts and warnings. 

1976: Based on its comprehensive measurements of man-made noise, ITS develops the CCIR / ITUR model still used today in radio link design. 

1978: ITS becomes part of the National Telecommunications and Information Administration. 

1979: Program for Regional Observing and Forecasting Systems (PROFS) is created in ERL to 

develop a weather forecast workstation for severe-storm warnings. 

1980: ETL demonstrates first high-energy pulsed Doppler lidar (which uses optical rather than radio 

frequencies) for atmospheric wind measurements, deployed the next year to monitor winds during 

landing of the second space shuttle flight. 

1986: Aeronomy Lab scientist proposes that the cause of the Antarctic ozone hole is the interaction 

of human-produced chlorine compounds with ice clouds in the upper atmosphere; scientists from

NOAA=s Aeronomy Lab and CMDL lead the first National Ozone Expedition to the South Pole that 

proves the theory correct, propelling international efforts to protect the ozone layer. 

1987: Study of superconductivity continues, and research finds more uses for big magnets, such as

magnetically levitated trains, and MRI imaging, which is widely used in medical science today. 

1988: The name we came to Boulder with changes—the National Bureau of Standards becomes the 

National Institute of Standards and Technology.

1989: Staff at NIST build a 10 volt reference standard involving 14,184 Josephson junctions 

operating simultaneously. 

1990: A new species of dinosaur—the only one named after a government agency—Drinker nisti, is 

discovered by Boulder NIST scientists and amateur paleontologists Jim Filla and Jim Siegwarth, 

along with CU professor Robert Bakker. 

1991: NIST scientists Drullinger, Glaze, Lowe, and Shirley improve upon NIST-7, the international 

time standard, with new laser-line narrowing methods. The new methods increased both accuracy

and stability for the atomic clock. 

7
1994: Developed by NOAA’s Forecast Systems Laboratory, the Rapid Update Cycle (RUC) weather 

forecast model becomes operational at the National Weather Service as the first forecast model using 

isentropic coordinates in the vertical and high frequency data for aviation, severe weather, and 

general forecasts. 

1995: ITS collaborates on a project to achieve land mobile radio (LMR) interoperability. 

1995: Scientists at JILA discover a new form of matter, the Bose-Einstein condensate. 

1996: FSL provides critical support for developing the core Advanced Weather Interactive 

Processing System (AWIPS) software, crucial to National Weather Service modernization across the 

country. 

1997: Climate Diagnostics Center researchers contribute to advancing a new approach to predicting 

U.S. El Niño climate impacts that is applied to the 1997–1998 El Niño. 

1998: Algorithms developed by ITS staff for estimating audio quality are adopted as an American 

National Standard. 

1999: NIST-F1, the cesium fountain clock, is unveiled and is currently the most accurate clock in the 

world. It loses less than one second every 20 million years and ticks over 9 billion times per second. 

1999: ETL conducts the first test of a buoy-mounted wind profiler, making possible better 

observations of conditions over the oceans, and leading to improved models for climate and weather 

forecasts. 

2001: Eric Cornell and Carl Wieman of JILA, and Wolfgang Ketterle of MIT win the 2001 Nobel 

Prize for Physics for their discovery of the Bose-Einstein condensate. 

2001: NIST celebrates its Centennial—The National Bureau of Standards was chartered by Congress 

on March 3, 1901. 

2001: ITS-developed glossary of telecommunications terms, previously a Federal Standard, becomes 

an American National Standard. 

2001: ITS characterizes ultrawideband (UWB) signals, which have been proposed as a partial 

solution to spectrum crowding. The results were used in a related study of the potential effects of 

UWB signals on GPS receivers. 

2003: ITS Video Quality Metric software is adopted as an American National Standard. 

2003: NOAA wind profiler network assists NASA in tracking debris from the space shuttle 

Columbia accident. 

2003: NIST Materials Reliability staff analyze the U.S. Capitol Dome for repairs and participate in 

research on New York’s World Trade Center disaster. 

2004: NOAA scientist Susan Solomon wins the prestigious Blue Planet Prize for her work in 

identifying the cause of the Antarctic ozone hole.

8
Papers from the 1950s 

The constants in the equation for atmospheric refractive index at radio frequencies 

 Ernest K. Smith, Jr., and Stanley Weintraub, 1953 10 

Measurements of the phase of radio waves received over transmission paths with 

electrical lengths varying as a result of atmospheric turbulence 

 Jack W. Herbstreit and Moody C. Thompson, 1955 11 

A refined X-band microwave microcalorimeter 

Glenn F. Engen, 1959 12 

Confidence intervals for the expectation of a Poisson variable 

 Edwin L. Crow and Robert S. Gardner, 1959 13 

Cryogenic engineering 

Russell B. Scott, 1959 14 

System loss in radio wave propagation 

Kenneth A. Norton, 1959 15 

The riometer—A device for the continuous measurement of ionospheric absorption 

 C. Gordon Little and Harold Leinbach, 1959 16 

9
The constants in the equation for atmospheric refractive index at radio 

frequencies 

Ernest K. Smith, Jr. and Stanley Weintraub 

 NBS Central Radio Propagation Laboratory 

Proceedings of the Institute of Radio Engineers, 41(8): 1035–1037, 1953 

Significance

When Ernie Smith came out to Boulder in 1951, his first job with the Central Radio Propagation 

Laboratory (CRPL) was to be head of the Radio Meteorology group. Discovering that the thenaccepted constants for the atmospheric refractive index were seriously in error, he felt that it was 

the responsibility of NBS to improve them. He and Stanley Weintraub gathered together the 

existing experimental data on dry air and on water vapor and put together this report. Smith left 

Boulder in 1952 to finish his Ph.D. at Cornell (returning a few years later) and the paper was 

published in the Proceedings of the IRE. The constants have held up amazingly well over time. 

Abstract 

Recent improvements in microwave techniques have resulted in precise measurements which 

indicate that the conventional constants K1 = 79°K/mb and K2′ = 4,800°K in the expression for 

the refractivity of air, N = (n – 1)106 = [K1/T](p + K2′ e/T) should be revised. Various laboratories 

appear to have arrived at this conclusion independently. In much of radio propagation work the 

absolute value of the refractive index of the atmosphere is of small moment. However, in some

work it is important and it seems highly desirable to decide upon a particular set of constant. 

Through consideration of the various recent experiments this paper arrives at a relation 

⎥

⎦

⎤ ⎢

⎣

⎡ = +

T

e

p TN 4,810 77.6 , 

where 

 p = total pressure in millibars 

e = partial pressure of water vapor in millibars 

T = absolute temperature = °C + 273 

This expression is considered to be good to 0.5 per cent in N for frequencies up to 30,000 mc and 

normally encountered ranges of temperatures, pressure and humidity. 

10
Measurements of the phase of radio waves received over transmission paths 

with electrical lengths varying as a result of atmospheric turbulence 

Jack W. Herbstreit and Moody C. Thompson 

 NBS Central Radio Propagation Laboratory 

Proceedings of the Institute of Radio Engineers, 43(10): 1391–1401, October 1955 

Significance

Jack Herbstreit, Chief of the Tropospheric Propagation Section of the CRPL, was the director of 

the Cheyenne Mountain tropospheric propagation experiments, which began in 1950, almost a 

year before the first CRPL employees arrived in Boulder. This paper, based on that project, looks 

at how atmospheric changes or discontinuities cause tropospheric scatter (“troposcatter”) of radio 

waves. Troposcatter is the propagation of radio waves by scattering as a result of irregularities or 

discontinuities in the physical properties of the troposphere, such as humidity, temperature, and 

pressure, and temporal changes such as wind or other movement. The measurements described in 

this paper enabled researchers to apply atmospheric parameters to extend the range of 

communication far beyond “line of sight.” Troposcatter was used as a method for transhorizon 

communications by the military beginning in the 1950s, most notably in the Distant Early 

Warning (DEW) line in northern Greenland, Canada, and Alaska, which was intended to warn 

against an over-the-pole invasion. These days troposcatter has been largely replaced by satellite 

communications; however, it is still used in some military applications, and in situations where 

relay stations are impractical. 

Abstract 

A system for the measurement of the variations in electrical lengths of radio propagation paths is 

described. The observed path-length instabilities are considered to be caused by the same

atmospheric turbulence responsible for the existence of very high frequency and ultra high 

frequency fields far beyond the radio horizon. Results obtained on 172.8 mc and 1,046 mc along 

31⁄2-, 10-, and 60-mile paths are reported. It is pointed out that measurements of this type provide 

a powerful tool for the study of the size and intensity of the refractivity variations of the 

atmosphere giving rise to the observed phenomenon. 

11
A refined X-band microwave microcalorimeter 

Glenn F. Engen 

 NBS Radio Standards Laboratory 

NBS Journal of Research 63C(1): 77–82, July–September 1959 

Significance

The paper describes the “Engen calorimeter” that appears in the Boulder Laboratories museum. 

This paper and a predecessor by Macpherson and Kerns of NBS in Washington, D.C., laid out 

basic principles of calorimeter design that are still applicable today. These design principles have 

been used at NIST and other national standards labs for over 40 years. A quick perusal of recent 

papers showed that at least four national measurement labs (China, Germany, Korea, and United 

Kingdom) have cited this paper since 1990, over 30 years after its original publication. 

Abstract 

The microcalorimetric method for evaluation of the efficiency and substitution error of a 

bolometer mount proposed by Macpherson and Kerns has been the object of further study and 

refinement at the Boulder Laboratories of the National Bureau of Standards, and an improved 

instrument based on this technique has been recently placed in operation. 

The new microcalorimeter design features are: (1) Greatly improved ambient temperature 

control, permitting higher sensitivity and resolution; (2) improved d-c instrumentation; (3) 

improved mechanical construction giving better repeatability; (4) relocation of the thermopile so 

that it no longer is attached directly to the bolometer mount, thus providing flexibility in the 

choice of termination; and (5) a more comprehensive treatment of the calorimetric substitution or

equivalence error. These features permit the determination of the effective efficiency of the 

bolometer mount to an accuracy better than 0.2 percent. 

12
Confidence intervals for the expectation of a Poisson variable 

Edwin L. Crow 

 NBS Central Radio Propagation Laboratory 

Robert S. Gardner 

 U.S. Naval Ordnance Test Station, China Lake, California 

Biometrika, 46: 441–453, 1959 

Significance

This paper presents a fundamental advancement in mathematical theory and practice for 

calculating confidence intervals (“error bars”) for the expectation of a Poisson-distributed 

random variable. The Poisson distribution is used to approximate the binomial distribution in 

situations where the number of “trials” is large and the probability of “success” on any individual 

trial is small. Such situations are commonly encountered in telecommunication performance 

measurement (e.g., measurement of bit or block error or loss ratios or blocking probabilities). 

Calculating confidence intervals can limit the duration and cost of such measurements. The 

technique described in this paper provides the narrowest possible confidence limits for 

measuring a Poisson random variable, and thus enables such measurements to be conducted with 

minimum measurement time and cost. Measurement methods based on this technique have been 

specified in national and international standards and are widely used in telecommunication 

performance assessment. 

Abstract 

A table of two-sided confidence intervals for the expectation of a Poisson variable is presented 

for confidence coefficients 0·80, 0·90, 0·95, and 0·999 and all values of the variable from 0 to 

300. We denote the Poisson variable by c and its expectation by m and plot them as rectangular 

coordinates, upper and lower confidence limits for m being plotted vertically along with c. If the 

successive upper limits for c = 0, 1, 2, ... be joined by line segments and the lower limits 

likewise joined, a semi-infinite region, called the confidence belt, is formed between the upper 

and lower broken lines. The confidence belt tabulated herein is determined by the properties (i) 

that, of all confidence belts for the Poisson expectation with a given confidence coefficient 

which are based directly on the Poisson variable c, it is as narrow as possible if width is 

measured in the horizontal c-direction; and (ii) that, of all such equally narrow confidence belts, 

it is that one with the smallest possible upper confidence limits. The second condition serves to 

minimize the lengths of the confidence intervals satisfying (i) for small values of c at the expense 

of inappreciable relative increase in length of larger values of c. 

13
Cryogenic engineering 

Russell B. Scott 

 NBS Cryogenic Engineering Laboratory 

Princeton, New Jersey: Van Nostrand Company, 1959 

Significance

This was the first book published on cryogenic engineering and was written by the former chief 

and founder of the Cryogenic Engineering Laboratory (CEL). In 1959, the book presented for the 

first time a written description of all the engineering principles and practices that are unique to 

the field of cryogenic engineering. Most of the material presented in this book summarizes the 

results from the extensive studies carried out at the CEL of the NBS Boulder Laboratories from

its founding in 1952 up to about 1958. Thus, there is much original work as well as a wonderful 

summary of nearly all that is important for cryogenic engineering. Even today, in 2004, 

researchers refer to this book quite often as a major source of information on cryogenic 

engineering. This monograph, since its publication, helped put the Boulder CEL on the map. 

Table of Contents 

I. Introduction 

II. Liquefaction of Gases 

III. Separation of Gases 

IV. Cooling by Adiabatic Demagnetization 

V. Low-Temperature Thermometry 

VI. Insulation 

VII. Storing and Transporting Liquefied Gases 

VIII. Transfer of Liquefied Gases 

IX. Properties of Cryogenic Fluids 

X. Low-Temperature Properties of Structural Materials 

14
System loss in radio wave propagation 

Kenneth A. Norton 

 NBS Central Radio Propagation Laboratory 

NBS Journal of Research, 63D(1): 53–73, August 1959 

Significance

Kenneth Norton developed the concept of transmission loss in describing the characteristics of 

tropospheric radio propagation. In this paper, he provided a full set of definitions for system, 

transmission, basic transmission, path antenna gain, and related concepts. These define the 

boundary between antenna and propagation path, and are fundamental to all propagation 

modeling. Norton also showed that by going to power (instead of field strength) for signal and 

noise, one can use a link budget and readily see the gains and losses in a system. Norton’s work 

on transmission loss led to one of CRPL’s most famous publications, Tech Note 101 (see 

Longley et al. 1965, this volume). 

Abstract 

A summary is presented of the ways in which the concept of system loss and the closely related 

concepts of transmission loss, basic transmission loss, propagation loss, and path antenna gain 

may be used for precise, yet simple, descriptions of some of the characteristics of radio wave 

propagation which are important in the design of radio systems. Definitions of various terms 

associated with the concept of system loss are given which introduce a greater flexibility into its 

use without any loss in precision. It is shown that the use of these added terms and concepts 

makes feasible the extension of the use of this method of description to any portion of the radio 

spectrum. A more general formula for the system loss is given which may be used for antennas 

with an arbitrarily small separation. Using this formula it is shown that the system loss between 

small electric or magnetic dipoles separated by a distance d « λ can be made arbitrarily small 

even though the individual antennas have large circuit losses. Formulas are developed for the 

percentage of time that a desired signal is free of interference, and these are used to demonstrate 

methods for the efficient use of the spectrum. In particular, contrary to general belief, it is shown 

that efficiency is promoted by the use of high power and high antennas and, in the case of a 

broadcast service, sufficiently small separations so that there is appreciable mutual interference. 

An analysis is made of the variance of the path antenna gain in ionospheric scatter propagation. 

Methods are given for the calculation of the transmission loss for the ground wave and 

tropospheric scatter modes of propagation through a turbulent model atmosphere with an 

exponential gradient. Examples of such calculations are given which cover a wide range of 

frequencies and antenna heights. Finally, examples are given of the expected range of various 

tropospheric point-to-point scatter systems such as an FM multichannel teletype system, a 

television relay or an FM broadcast relay. 

15
The riometer: A device for the continuous measurement of ionospheric 

absorption 

C. Gordon Little 

 NBS Central Radio Propagation Laboratory 

Harold Leinbach 

 Geophysical Institute, University of Alaska 

Proceedings of the Institute of Radio Engineers, 47, 315–320, 1959 

Significance

The riometer (relative ionospheric opacity meter) measures the intensity of wideband noise that 

impinges on the earth from deep space. The equipment consists of a stable receiver, a suitable 

antenna, a recorder, and a noise diode antenna. Ionospheric absorption had heretofore been very 

difficult to measure, so this method was a real boon to ionospheric physics. It is still being used 

for studies of the ionosphere, especially regarding solar flares and geomagnetic storms. 

Abstract 

A sensitive, self-balancing, noise-measuring equipment, known as the riometer, is described. 

This instrument has been designed for routine measurement of ionospheric absorption during the 

IGY, using the cosmic noise method. Application of this technique in the auroral zone has 

resulted in quantitative measurements of ionospheric absorption, even during polar blackouts. 

The riometer has the advantages over a simple total-power cosmic noise receiving system of (1) 

linear response to changes of input noise power, (2) high accuracy in the presence of narrowband RF interference, and (3) good long-term stability. 

16
Papers from the 1960s 

A comparison of atomic beam frequency standards 

 Roger E. Beehler, Richard C. Mockler, and Charles S. Snider, 1960 19 

Advances in cryogenic engineering, Vol. 1, Proceedings of the 1954 Cryogenic 

Engineering Conference 

Klaus D. Timmerhaus, 1960 20 

Apparatus for determination of pressure-density-temperature relations and specific 

heats of hydrogen to 350 atmospheres at temperatures above 14 K 

Robert D. Goodwin, 1961 21 

Electromagnetic waves in stratified media 

James R. Wait, 1962 22 

A survey of ionospheric effects upon earth-space radio propagation 

 Robert S. Lawrence, C. Gordon Little, and Hugh J.A. Chivers, 1964 23 

Characteristics of the earth-ionosphere waveguide for VLF radio waves 

 James R. Wait and Kenneth P. Spies, 1964 24 

Radio propagation by reflection from meteor trails 

George R. Sugar, 1964 25 

Wave hop theory of long distance propagation of low-frequency radio waves 

Leslie A. Berry, 1964 26 

Ionospheric radio propagation 

Kenneth Davies, 1965 27

Transmission loss predictions for tropospheric communication circuits 

 Philip L. Rice, Anita G. Longley, Kenneth A. Norton, and Albrecht P. Barsis, 1965 28 

Measuring oscillator and clock performance: 

1. Atomic timekeeping and the statistics of precision signal generators 

James A. Barnes, 1966 29 

2. Statistics of atomic frequency standards 

David W. Allan, 1966 29 

Calorimetric measurement of pulsed laser output energy 

Donald A. Jennings, 1966 31 

17
Radio meteorology 

 Bradford R. Bean and Evan J. Dutton, 1966 32 

Thermal-energy associative-detachment reactions of negative ions 

 Fred C. Fehsenfeld, Eldon E. Ferguson, and Arthur L. Schmeltekopf, 1966 33 

Thermodynamic properties of He3

-He4 solutions with applications to the He3-He4 

dilution refrigerator 

Ray Radebaugh, 1967 34 

Development and operation of a specialized technical information and data center 

(the Cryogenic Data Center) 

Victor J. Johnson, 1968 35 

Prediction of tropospheric radio transmission loss over irregular terrain: 

A computer method 

 Anita G. Longley and Philip L. Rice, July 1968 36 

Acoustic methods for remote probing of the lower atmosphere 

C. Gordon Little, 1969 37 

18
A comparison of atomic beam frequency standards 

Roger E. Beehler, Richard C. Mockler, and Charles S. Snider 

 NBS Time and Frequency Division 

Nature 187: 681–682, 1960 

Significance

This paper is primarily of interest for historical reasons, describing the atomic clock (NBS 2) that 

became in 1960 the first U.S. atomic standard for time and frequency. The clock was not only a 

substantial improvement in accuracy for measuring time and frequency, but also the first 

standard based on fundamental properties of matter rather than an artifact (such as the standard 

kilogram or a complex device such as the array of quartz oscillators that previously served as the 

national standard for time and frequency). 

NBS created the world’s first atomic clock in 1949 in Washington, D.C., based on transitions in 

ammonia molecules. In 1952, NBS adapted the science and technology to beams of cesium

atoms in NBS 1, its first atomic clock intended as a standard. However, NBS 1 was not 

sufficiently reliable to serve as an operational standard. The U.S. national standard for time and 

frequency remained an ensemble of quartz oscillators. In 1954, the atomic clock program was 

transferred to the new Boulder Laboratories. The Boulder Labs developed NBS 2, which had 

electronic servo-control that enabled the atomic clock for the first time to be operated reliably 

and automatically. On January 1, 1960, NBS 2 was officially installed as the nation’s time and 

frequency standard. The paper reports the comparison of NBS 1 and NBS 2, demonstrating an 

uncertainty of about 1.5 parts in 1011, equivalent to about 1 second in 2,000 years. Since that 

time, NBS/NIST has improved the performance of atomic clocks by a factor of about 10 per 

decade, with the current NIST-F1 laser-cooled atomic fountain clock having an accuracy of 

about 1 part in 1015, equivalent to about 1 second in 30 million years. This continual 

improvement has led to transforming commercial applications, such as the Global Positioning 

System and cellular communications networks, and to new scientific applications such as 

precision tests of quantum mechanics, relativity, and astrophysics. Atomic clocks quickly 

became so accurate that it became clear the rotation of the earth changed by small amounts in 

unpredictable ways. Thus by international agreement in 1967, the second was redefined in terms

of the cesium atomic clock transition, replacing the definition based on the rotation of the earth. 

Thanks to continuing advances in atomic clocks, the second is by far the most accurately realized 

of the seven fundamental units. 

19
Advances in cryogenic engineering, Vol. 1, 

Proceedings of the 1954 Cryogenic Engineering Conference 

Klaus D. Timmerhaus, Editor 

 NBS Cryogenic Engineering Laboratory and 

 University of Colorado 

New York: Plenum Press, 1960 

Significance

This first conference on cryogenic engineering was organized by NBS and started what has 

become the biennial Cryogenic Engineering Conference (CEC) that when combined with the 

Cryogenic Materials Conference attracts about 800 to 900 participants from around the world. It 

is the largest conference in the field of cryogenic engineering. Klaus Timmerhaus was a 

professor in the Chemical Engineering Department at the University of Colorado, but was also 

employed at NBS as a part time employee for many years. 

Abstract (since the book has no abstract, an excerpt from the Foreword is included) 

... . Cryogenic engineering is concerned with developing and improving low temperature 

processes, techniques, and equipment; determining the physical properties of structural and 

related materials used in producing, maintaining, and using low temperatures; and the practical 

application of low temperature techniques and processes. These low temperatures are below 

those usually encountered in refrigerating engineering. It is rather difficult to assign a definite 

temperature which serves to divide refrigerating engineering from cryogenic engineering. A 

temperature below –150°C, however, is generally associated with cryogenic engineering. 

There is ample reason for treating cryogenic engineering as a special field of engineering. The 

physical properties of materials at very low temperatures differ so markedly from those 

commonly encountered that the engineer cannot rely on his ordinary experience. Because of the 

rapid growth of this field of engineering in the past ten to fifteen years, many new and highly 

complex engineering problems have arisen in the low temperature field. In order to improve the 

interchange of information among organizations active in cryogenic engineering, the National 

Bureau of Standards–Atomic Energy Commission Cryogenic Engineering Laboratory in 

Boulder, Colorado, sponsored the first Cryogenic Engineering Conference on September 8, 9, 

and 10, 1954, at the National Bureau of Standards Boulder Laboratories... . 

20
Apparatus for determination of pressure-density-temperature relations and 

specific heats of hydrogen to 350 atmospheres at temperatures above 14 K 

Robert D. Goodwin 

 NBS Cryogenic Engineering Laboratory 

NBS Journal of Research 65C(4): 231–243, 1961 

Significance

The determination of the relation among temperature, pressure, and density is a key problem in 

establishing the important thermodynamic properties of a fluid. The apparatus described in this 

paper remains as a near state-of-the-art system for wide ranging measurements, and its 

capabilities have been extended through automation and an increase in the temperature range. 

The instrument has been used nearly continuously for more than 40 years to measure PVT 

relations and specific heats of numerous fluids, and the apparatus can be considered the heart and

soul of the fluid property measurement program in Boulder. The early measurements on 

hydrogen described here form the basis of current standards on hydrogen properties (of keen 

interest for the “hydrogen economy”), and the uncertainty assessment described for the apparatus 

remains an exemplary protocol for density metrology. 

Abstract

Method and apparatus are designed for more rapid determination of accurate, closely spaced, 

PVT and specific heat data than realized by previous procedures. A sequence of pressuretemperature observations at nearly constant density is made by a modified Reichsanstalt method. 

Temperatures of the essentially adiabatic piezometer are regulated by electric heating under 

control of the measuring thermometer. Instruments for measurement and control are integrated 

with a high-pressure calorimeter for compressed liquid and fluid. Calorimetric experimentation is 

accelerated by use of an electronic battery for the calorimetric heat supply and of a d-c power 

regulator developed for automatic shield control. Details are given of the PVT calibrations, 

adjustment computations, and comparisons with independent data. 

21
Electromagnetic waves in stratified media 

James R. Wait 

 NBS Central Radio Propagation Laboratory, and 

 University of Colorado 

New York: Pergamon Press, 1962 (revised 1970) 

Significance

This book is based on fundamental research in electromagnetic wave propagation that Wait 

performed in the CRPL from 1956 to 1962. The mathematical formulations are very general, and 

the “stratified media” models are applicable to the earth crust, troposphere, and ionosphere. The 

frequencies of the communication, navigation, and remote sensing applications range from

extremely low frequencies to microwaves. The propagation theories in the book have served to 

guide experimental and theoretical tropospheric and ionospheric propagation programs both 

within the Boulder Labs and worldwide for over three decades. Cited over 1500 times, it was 

reissued by IEEE Press in 1996. 

Abstract 

This book is concerned with electromagnetic waves in media whose properties vary in one 

particular direction. The variation may consist of abrupt or continuous changes. In this sense the 

media may be generally classified as stratified. This is an idealization of many situations which 

occur in nature. For example, there is a tendency for our terrestrial atmosphere to occur in 

horizontal layers. Similarly, the properties of the earth’s crust do not vary significantly in the 

horizontal direction. Consequently, a proper understanding of wave phenomena in stratified 

media is of great practical importance. The major theoretical task is to find solutions of

Maxwell’s field equations which satisfy the appropriate conditions imposed by the various 

boundary conditions.

Rather than present a sterile and formal treatment couched in the language of the mathematician,

a physical approach is adopted. Furthermore, applications to the real world are used as 

illustrations of the theoretical principles. Special emphasis is given to radio waves in the 

frequency range from 3 to 30 kc/s which is described as v.l.f. (very low frequency). These 

frequencies correspond to wavelengths ranging from 100 to 10 km. In such cases the ionized 

layers in the upper atmosphere do indeed behave as stratified media since the scale of the 

irregularities is usually small compared with the wavelength. In addition, many comparisons are 

made with experimental data on v.l.f. radio transmissions since only in this way can we ascertain

if the adopted theoretical model has any real significance. An important feature of these waves is 

their low attenuation which enables communications at global distances. In addition, they exhibit 

remarkably stable phase characteristics... . 

22
A survey of ionospheric effects upon earth-space radio propagation 

Robert S. Lawrence, C. Gordon Little, and Hugh J.A. Chivers 

 NBS Central Radio Propagation Laboratory 

Proceedings of the Institute of Radio Engineers, 47, 315–320, 1964 

Significance

This paper was an attempt by the CRPL to bring some order and understanding to what was then 

the new field of earth-space radio propagation. It was the most accurate and authoritative text on 

the subject at the time, and was considered by the Laboratory to have put to rest various 

questions regarding Faraday rotation, group and phase delay, total electron content and 

ionospheric absorption of radio waves transiting the ionosphere. Advances in high power, high 

frequency transmission have made satellite communications much less difficult, but the work in 

this paper remains useful to this day.

Abstract 

The frequency dependence is derived and the order of magnitude is presented for various 

ionospheric effects upon radio waves which have frequencies greater than the penetration 

frequency of the ionosphere. Among the phenomena considered are phase-path length change, 

refraction, frequency change, group-path delay, polarization rotation, and absorption. A detailed 

discussion is given of the mean value and variability of ionospheric absorption, refraction, 

scintillations, and polarization changes. 

23
Characteristics of the earth-ionosphere waveguide for VLF radio waves 

James R. Wait and Kenneth P. Spies 

 NBS Central Radio Propagation Laboratory 

NBS Technical Note 300, December 30, 1964 

Significance

Dr. Wait came up with the idea of modeling the propagation of VLF radio waves, used in 

military applications, by thinking of the space between the earth and the ionosphere as a kind of 

giant “waveguide” for the extremely long VLF radio waves. A waveguide is a device, usually a 

hollow round or rectangular tube, used to trap radio waves and guide them internally to another 

location. This Technical Note included both the mathematics for VLF earth-ionosphere 

waveguide propagation and extensive numerical results for frequencies from 8 to 30 kHz. In the 

days before fast computers, this was the first publication to present extensive numerical results 

for the relevant propagation parameters (attenuation rate, phase velocity, and field distribution) 

for a realistic curved earth and layered ionosphere model. The graphical results that are included 

were the only ones available for many years, and as a result this publication received an 

unusually large number of citations in the literature. 

Abstract 

The principal results of this technical note are graphical presentations of the attenuation rates, 

phase velocities, and excitation factors for the dominant modes in the earth-ionosphere 

waveguide. The frequency range considered is 8 kc/s to 30 kc/s. The model adopted for the 

ionosphere has an exponential variation for both the electron density and the collision frequency, 

and the effect of the earth’s magnetic field is considered. Comparison with published

experimental data confirms that the minimum attenuation of VLF radio waves in daytime is 

approximately at 18 kc/s, while at night it is somewhat lower. The directional dependences of 

propagation predicted by the theory are also confirmed by experimental data. 

24
Radio propagation by reflection from meteor trails 

George R. Sugar 

 NBS Central Radio Propagation Laboratory 

Proceedings of the Institute of Electrical and Electronics Engineers, 52(2): 116–136, 1964 

Significance

In the early 1960s George Sugar developed one of the earliest examples of packet transmission. 

As meteors travel through the ionosphere they leave a column of ions which, when the aspect 

ratio is just right, allow a few seconds of radio transmission at frequencies well above the normal 

critical frequency of the ionosphere. The trick was to send a burst of signal during that brief 

period of transmission, then wait for the next favorable meteor trail to send the next. Sugar’s 

paper, as well as his system, pioneered a new mode of propagation. This classic paper on the 

interaction of radio waves and meteors has recently been rediscovered due to renewed interest in 

meteor burst communications as an inexpensive (and now much more feasible) tool for longdistance communication. 

Abstract 

This paper is a survey of those characteristics of meteors, and of meteor propagation, which are 

important to the understanding and use of meteor ionization insofar as it provides a means of 

radio transmission. The subjects discussed include the utility of meteor bursts for intermittent 

radio communication, physical properties of meteors and meteor trails, reflection properties of 

individual trails, short-term statistical characteristics of received signals, and long-term statistical 

characteristics of received signals. 

25
Wave hop theory of long distance propagation of low-frequency radio waves 

Leslie A. Berry 

 NBS Central Radio Propagation Laboratory 

Radio Science Journal of Research NBS/USNC–URSI, 68D(12): 1275–1284, December 1964 

Significance

This paper provides a practical method of calculating field strength for propagation of lowfrequency radio waves over long distances in the LF and VLF frequency bands, when the 

propagation distances are well into the shadow region (the region beyond the radio horizon 

where radio waves must bend around the Earth). LF and VLF waves were and still are important 

for certain types of long distance communications, e.g., with submarines. The method presented 

in the paper is a simple physical interpretation of a very complex process, and represents a 

breakthrough in computation techniques for wave-hop propagation. The author demonstrates that 

this technique is valid not only for the homogeneous case, but also for the nonhomogeneous 

anisotropic case with only a small error. The characteristics of the propagation path that 

determine its delay include ground conductivity, distance, earth curvature, and height of 

reflection. The innovative computation theory presented in the paper was an important 

contribution to the scientific community at the time it was written. 

Abstract 

The idea that long radio waves propagating between the earth and ionosphere via discrete hops 

can be extended far into the shadow region by evaluating a series of complex integrals is 

exploited in this paper. Illustrative calculations of LF and VLF hops and total fields are shown as 

a function of distance. The second and higher hops show a pseudo-Brewster angle just before the 

caustic and attenuate like groundwaves in the shadow region. 

The form of the series of integrals for an anisotropic ionosphere is given, and a model 

anisotropic ionosphere varying with height is used in a sample calculation. 

Only a small error is caused by writing each hop as the product of an effective ionospheric 

reflection coefficient and an integral which is a function only of the other characteristics of the 

path. 

26
Ionospheric radio propagation

Kenneth Davies 

 NBS Central Radio Propagation Laboratory 

NBS Monograph 80, 1965 (Revised, updated, and reissued as Ionospheric Radio, IEE 

Electromagnetic Waves Series 31, Peter Peregrinus, Ltd., 1989) 

Significance

The main function of the CRPL when it was formed in 1947 was the prediction of HF 

ionospheric propagation. Knowledge of how the ionosphere affects propagation was vital in 

radio communications. An early publication, NBS Circular 462, became a worldwide handbook. 

In 1957, the revision of this handbook was assigned to Ken Davies, a new employee. The result, 

which incorporates radio propagation research performed in Boulder during the 1950s and 

1960s, was NBS Monograph 80, reprinted in 1966 by Dover. This excellent, broad-based text is 

notable for its clarity and accessibility. 

For practitioners of HF communications and surveillance, Davies’ books have been an 

invaluable reference. In fact, until the 1990s, Davies’ books were the only sources for 

information about the practical aspects of radio wave propagation within and through the 

ionosphere. Most recent texts on HF communications and encyclopedia articles on the 

ionosphere refer to Monograph 80 and its later edition. Davies’ books have been of value in 

many civilian and defense system developments, and in the evaluation of a number of earthspace and terrestrial communication concepts. This book set out to bridge the gulf between the 

pure scientific understanding of the ionosphere and the real world of commercial radio 

communication. Its success is demonstrated by the fact that some 40 years after the first edition, 

this text is still used by scientists and engineers. The original edition has had nearly 90 citations 

since 1975 and continues to be referenced now. 

Abstract

There is not an abstract associated with the 1965 Monograph. However, the flyleaf of the 1989 

edition sums up the intent and nature of the earlier work as well as the more recent. “Ionospheric 

Radio replaces an earlier publication, Ionospheric Radio Propagation, and is aimed at 

professional scientists, engineers, and students who need an intermediate-level reference and/or

text. Students of aeronomy and radio wave propagation are introduced to basic wave theory in 

absorbing, anisotropic and dispersive media and to the physics of the production, loss, and 

movement of plasma in the ionosphere in the presence of the geomagnetic field. Various radio 

techniques are described and applications to the interpretation of ionospheric data to radio 

communications problems are presented. Topics include Earth-space propagation, ionospheric 

modification, ionospheric disturbances, propagation by scattering from plasma irregularities, 

topside sounding, and propagation on frequencies from the extremely low to the super high.” 

27
Transmission loss predictions for tropospheric communication circuits 

Philip L. Rice, Anita G. Longley, Kenneth A. Norton, and Albrecht P. Barsis 

 NBS Central Radio Propagation Laboratory* 

 *Note: the 1967 revision, which is the definitive version, lists their affiliation as Institute for 

Telecommunication Sciences and Aeronomy, Environmental Science Services Administration

NBS Technical Note 101, May 7, 1965 (revised May 1, 1966, and January 1, 1967) 

Significance

The detailed point-to-point methods described in “Tech Note 101” established the basic 

framework for nearly all subsequent practical radio propagation prediction models, including the 

famous Longley-Rice model (also known as the Irregular Terrain Model). These methods serve 

as the basis for making quantitative estimates of radio propagation that, for example, determine 

how well a proposed radio system will meet the requirements for satisfactory service, free from

harmful interference, thereby promoting more efficient use of the radio frequency spectrum. 

Nothing else has the breadth of this publication, which is why it is still very much sought after 

today. 

Abstract 

This report represents comprehensive methods for predicting cumulative distributions of 

transmission loss for a wide range of radio frequencies over any type of terrain and in several 

climatic regions. Such quantitative estimates of propagation characteristics help to determine 

how well proposed radio systems will meet requirements for satisfactory service, free from

harmful interference. Thus they should provide an important step toward more efficient use of 

the radio frequency spectrum. 

The need for comprehensive and accurate prediction methods is clearly demonstrated when 

measured transmission loss data for a large number of radio paths are shown as a function of 

path length. In figures I.1 to I.4 of annex I, long-term median values of attenuation relative to 

free space for more than 750 radio paths are plotted versus distance. The extremely wide scatter 

of these data is due mainly to path-to-path differences in terrain profiles and effective antenna 

heights. Values recorded for a long period of time over a single path show comparable ranges, 

sometimes exceeding 100 decibels. Such tremendous path-to-path and time variations must be 

carefully considered, particularly in cases of possible interference between co-channel or 

adjacent-channel systems. 

The detailed point-to-point prediction methods described here depend on propagation path 

geometry, atmospheric refractivity near the surface of the earth, and specified characteristics of 

antenna directivity. They have been tested against measurements in the radio frequency range of 

40 to 10,000 MHz (megacycles per second)... . 

28
Measuring oscillator and clock performance: 

1. Atomic timekeeping and the statistics of precision signal generators 

James A. Barnes 

 NBS Time and Frequency Division 

Proceedings of the Institute of Electrical and Electronics Engineers, 54: 207-220, 

February 1, 1966 

2. Statistics of atomic frequency standards 

David W. Allan 

 NBS Time and Frequency Division 

Proceedings of the Institute of Electrical and Electronics Engineers, 54: 221-231, 

February 1, 1966 

Significance

These two papers, appearing back-to-back in the same journal, build on each other to describe a 

crucial new statistical method to evaluate the performance of oscillators and timekeeping 

devices. This new method rapidly became universally used to measure oscillator and clock 

performance, and users quickly began calling it the “Allan variance” in recognition of one of the 

NBS scientists who developed the method. 

NBS scientists James Barnes and David Allan recognized that standard statistics such as the 

mean and standard deviation were woefully inadequate to measure the performance of oscillators

(such as quartz crystals, atomic clocks, etc.) because the noise in the systems depended on the 

frequency and/or observation time itself. Barnes and Allan conducted experiments and 

theoretical analyses to develop a new statistic based on second-difference methods which proved 

extremely useful for specifying the performance of oscillators and clocks, by frequency or by 

time of observation. This statistic became known as the “Allan variance” (although it probably 

should be called the “Allan–Barnes variance”) and is now universally used by equipment 

manufacturers, test engineers, and researchers to specify the performance of oscillators. The 

statistic enables not just an overall specification of performance, but also in many cases 

identification of the different causes of noise in the system under test. Researchers at NBS/NIST 

and elsewhere expanded on the concept of the original Allan variance to develop a number of 

other closely related statistics which are also used to measure particular aspects of oscillator and 

system performance. Major users of the Allan variance and its close relatives include the 

telecommunications industry, defense applications, broadcasters, surveillance applications 

(radar, etc.), aerospace industry, and the time and frequency research community. 

29
Abstract 1 

Since most systems that generate atomic time employ quartz crystal oscillators to improve 

reliability, it is essential to determine the effect on the precision of time measurements that these 

oscillators introduce. A detailed analysis of the calibration procedure shows that the third finite 

difference of the phase is closely related to the clock errors. It was also found, in agreement with 

others, that quartz crystal oscillators exhibit a “flicker” or |ω|

-1 type of noise modulating the 

frequency of the oscillator. 

The method of finite differences of the phase is shown to be a powerful means of classifying the 

statistical fluctuations of the phase and frequency for signal generators in general. By employing 

finite differences it is possible to avoid divergences normally associated with flicker noise 

spectra. Analysis of several cesium beam frequency standards have shown a complete lack of the 

|ω|

-1 type of noise modulation. 

Abstract 2 

A theoretical development is presented which results in a relationship between the expectation 

value of the standard deviation of the frequency fluctuations for any finite number of data 

samples and the infinite time average value of the standard deviation, which provides an 

invariant measure of an important quality factor of a frequency standard. A practical and 

straightforward method of determining the power spectral density of the frequency fluctuations 

from the variance of the frequency fluctuations, the sampling time, the number of samples taken, 

and the dependence on system bandwidth is also developed. Additional insight is also given into 

some of the problems that arise from the presence of “flicker noise” (spectrum proportional to 

|ω|

-1) modulation of the frequency of an oscillator. 

The theory is applied in classifying the types of noise on the signals of frequency standards made 

available at NBS, Boulder Laboratories, such as: masers (both H and N15H3), the cesium beam

frequency standard employed as the U.S. Frequency Standard, and rubidium gas cells. 

“Flicker noise” frequency modulation was not observed on the signals of masers for sampling 

times ranging from 0.1 second to 4 hours. In a comparison between the NBS hydrogen maser and 

the NBS III cesium beam, uncorrelated random noise was observed on the frequency fluctuations

for sampling times extending to 4 hours; the fractional standard deviations of the frequency 

fluctuations were as low as 5 parts in 1014. 

30
Calorimetric measurement of pulsed laser output energy 

Donald A. Jennings 

 NBS Radio Standards Physics Division 

IEEE Transactions on Instrumentation and Measurement, IM-15: 161–164, 1966 

Significance

This paper reports the development of the first primary standard for laser energy measurements. 

NBS was the first national measurement institute to have such a standard, and provided the first 

traceable calibrations beginning in 1967. 

Abstract 

There are several methods by which one may measure the energy output of the pulsed laser. 

However, the technique which seems to be most promising as far as accuracy and precision are 

concerned is the calorimetric method. We have designed, built, and calibrated calorimeters for 

measuring the output energy of the pulsed ruby laser (6943Å). The heart of the calorimeter is a 

small absorption cell containing an aqueous solution of CuSO4. The temperature of the 

absorption cell, as measured by a thermocouple, indicates the energy absorbed by the 

calorimeter. The calorimeter was calibrated in two different ways: (1) the known heat capacity of

the absorption cell and the thermocouple sensitivity calibration gives a calorimeter calibration, 

which agrees within 0.3 percent of (2) an electrical energy substitution calibration which is 

obtained via a heater wire contained in the absorption cell solution. A method has been devised 

by which two calorimeters may be intercompared. Calorimeters which we have built and 

calibrated agree with each other to about 0.7 percent. This specific calorimeter has been designed 

to measure energies up to 30 J and will take peak powers of up to 200 MW/cm2

. 

31
Radio meteorology 

Bradford R. Bean and Evan J. Dutton

 NBS Central Radio Propagation Laboratory 

NBS Monograph 92, March 1, 1966

Significance

Radio Meteorology, published by NBS in 1966 and republished by Dover in 1968, is a 

compilation of work performed by the Central Radio Propagation Laboratory in radio 

meteorology during the previous decade. It is one of very few treatments of this subject, certainly 

the only one that goes into this much depth. Its focus is on the refraction, or bending, of radio 

waves by the atmosphere, under various meteorological conditions. Because the radio refractive 

index of air is a function of atmospheric pressure, temperature, and humidity, radio signals vary 

according to the time of year and the climate. They may also be attenuated by atmospheric gases 

and weather phenomena such as clouds, rain, and fog. Therefore, information in this monograph 

enables engineers to predict whether their communications systems will function properly in a 

specific place under specific conditions at a specific time of year. Radio Meteorology has been 

translated into several languages and is considered the “bible” on the subject, with maps from

this volume showing up in various ITU Recommendations. The two editions have a total of 260 

citations in the Science Citation Index since 1975. 

Abstract 

This volume brings together the work done in radio meteorology over the past ten years at the 

National Bureau of Standards’ Central Radio Propagation Laboratory (CRPL). This decade has 

seen the development, on an international scale, of great emphasis upon the effects of the lower 

atmosphere on the propagation of radio waves. The CRPL group has concentrated upon the 

refraction of radio waves as well as the refractive index structure of the lower atmosphere on 

both synoptic and climatic scales. These are the areas of radio meteorology that are treated in this 

volume, with additional chapters on radio-meteorological parameters and the absorption of radio 

waves by the various constituents of the lower atmosphere. An effort has been made to include 

results obtained in other laboratories both in the United States and abroad. 

32
Thermal-energy associative-detachment reactions of negative ions

Fred C. Fehsenfeld, Eldon E. Ferguson, and Arthur L. Schmeltekopf 

 ESSA Institute for Telecommunication Sciences and Aeronomy 

Journal of Chemical Physics, 43(5): 1844–1845, 1966 

Significance

This paper describes the discovery of an entirely new kind of reaction that occurs in the 

atmosphere, which the authors name “associative-detachment” reactions. In these reactions, a 

negatively charged molecule or atom reacts with a neutral species to release a “free” (unattached) 

electron and produce a new molecule. In the Earth’s upper atmosphere, any process that releases 

free electrons is highly significant—electrons are the governing influence on the transmission of 

radio waves in the atmosphere. The new finding was therefore critical not only to 

telecommunications, but to national security and defense. The discovery came when researchers 

at the just-formed Aeronomy Laboratory were forging the very first understanding of the 

chemistry of the Earth’s ionosphere (a region in the upper atmosphere, above the stratosphere, 

where charged particles exist because of high-energy radiation that the atmosphere receives at 

those high altitudes). It was critically important to develop a scientific understanding of the 

chemistry of the ionosphere, because of its influence on radio transmissions and the implications 

for communications and national security. This paper was a true breakthrough, because it 

announced that a whole new category of reactions existed that had a high impact on radio 

transmission in the atmosphere. The paper made impressive headway in announcing first results. 

Usually, a paper describes only one or a very small number of reactions—but Fehsenfeld et al. 

identified fifteen examples of the new types of reaction and specified the rates (speeds) at which 

they occur. As lead author Fred Fehsenfeld recalls, the researchers sensed that, as they

discovered this new type of reaction in the laboratory, they were indeed working on a very 

exciting new frontier of atmospheric science. They were eager to announce their discovery, 

publishing it rapidly in the “letters” section of the Journal of Chemical Physics. It was a true 

“first” in the field of atmospheric chemistry. 

Abstract

The ESSA-flowing afterglow reaction system which has been extensively used for thermalenergy positive-ion-neutral reaction studies has now been applied to negative-ion-neutral 

reaction studies. The following preliminary results suggest a fairly general behavior of negative 

ions reacting with neutrals, which has not been previously recognized. This is that many 

exothermic associative-detachment reactions appear to be rapid at thermal energies. These results 

have obvious important implications for the ion chemistry of the earth’s lower ionosphere, for 

the chemistry of electro-negative gases in electrical discharges, and for deionization in discharge 

afterglows and in flames.

33
Thermodynamic properties of He3

-He4 solutions with applications to the 

He3

-He4 dilution refrigerator 

Ray Radebaugh 

 NBS Cryogenics Division 

NBS Technical Note 362, 1967 

Significance

This 134-page Tech Note is noteworthy for two reasons. (1) It was the first publication to 

provide detailed thermodynamic properties with extensive tables and graphs of mixtures of He3

and He4

 liquids for temperatures in the range from 0 K to 1.5 K. (2) It gave a detailed 

thermodynamic analysis for the first time of the He3

-He4 dilution refrigerator, which had been 

invented in 1966. A few other explanations of the dilution refrigerator had existed before, but 

they were difficult to follow and no longer used after the explanation from this Tech Note 

appeared. The dilution refrigerator has become a very important tool in low temperature physics 

and even today most people involved with the design of such refrigerators still refer to and use 

the properties given in Tech Note 362. 

Abstract 

The thermodynamic properties of liquid He3

–He4 solutions between 0 and 1.5°K are calculated 

by using the weakly interacting Fermi–Dirac gas model for He3

 in He4. Certain experimental 

data below about 0.4°K are used to evaluate some of the parameters in the model. The properties 

of both He3

 in He4 and the total solution are calculated for concentrations of He3 up to 30 

percent. All experimental data agree very well with the calculated results, although little data 

exist below 0.4°K. The calculated properties are used to analyze the behavior of the He3

–He4

dilution refrigerator in both the continuous and single-cycle processes. The maximum heat 

absorption below about 0.04°K is found to be 82 T2

 joules per mole of He3 circulated. The effect 

of an imperfect heat exchanger and He4

 circulation on the refrigeration capacity is discussed. An 

analysis of two new types of single-cycle processes is also given. 

34
Development and operation of a specialized technical information and data 

center (the Cryogenic Data Center) 

Victor J. Johnson 

 NBS Institute for Basic Standards 

Journal of Chemical Documentation 8: 219–224, 1968 

Significance

The Cryogenic Data Center was established at NBS in Boulder in 1958 to “cope with the 

problem of organizing the world’s literature” in cryogenics and providing “reliable information 

and data.” The field of cryogenics may have started in 1883 (with the liquefaction of air), and the 

interest in Boulder began with the opening of the Boulder Laboratories 50 years ago. The 

activities of collecting, evaluating, and disseminating information have been ongoing in Boulder, 

with emphasis ranging from cryogenics, to key fluids, to current efforts on essentially all 

chemical systems; the specific techniques used from the punch cards and magnetic tapes 

described in this paper to automated web-based and “expert” systems have evolved over the 

years. The bustling Cryogenic Data Center established some of the key features of information 

exchange that are at the heart of the “information and knowledge management” efforts of today. 

Abstract

As is typical of many specialized areas of science and technology, cryogenics has had an 

explosive development in the last decade and a half. The Cryogenic Data Center was established 

in 1958 to cope with the problem of organizing the world’s literature pertinent to the field of 

cryogenics and furnishing this rapidly developing industry with reliable information and data. 

The development of this facility over the 10-year period of its existence is discussed. Included is 

a description of the conversion from a manual to an automated bibliographic retrieval system, the 

development of cataloging and indexing techniques, the development of comprehensive 

awareness and literature acquisition procedures with public announcement of new literature, 

procedures for selecting and compiling data, and finally how the needs of the sponsors and the 

industry are being served. The discussion emphasizes the problems that are typical in facilities of 

this type and the need to consider standard or generally accepted solutions. The growing trend 

for a network system of technical information and data centers requires a high order of 

compatibility among them. 

 

35
Prediction of tropospheric radio transmission loss over irregular terrain: A 

computer method 

Anita G. Longley and Philip L. Rice 

 ERL Institute for Telecommunication Sciences and Aeronomy 

ESSA Technical Report ERL 79-ITS 67, July 1968 

Significance

The “Computer Method” provides the first detailed, comprehensive description of the general 

purpose radio propagation prediction model that subsequently became the ITS Irregular Terrain 

Model (ITM or Longley–Rice Model). It can be applied to a wide variety of radio engineering 

problems. Although the model is based in part on the concepts and methods of calculation found 

in Tech Note 101 (Rice et al., 1965–1967, this volume), there are numerous refinements and 

details of the implementation that are unique to this publication. This publication preceded the 

advent of the widespread availability of digital terrain elevation databases, so for a number of 

years the model was principally used in its area (or site-general) mode. More recently, good 

quality digital terrain elevation databases have become widely available, so the model has been 

used for radio system design and planning in its point-to-point (or site-specific) mode. Two 

recent examples of this use include the presumption of terrestrial broadcast service (or lack 

thereof) for the purposes of satellite delivery of distant network signals under the Satellite Home

Viewer Improvement Act and the FCC’s use of the model to develop the Table of Allotments for 

digital television. 

Abstract 

This report describes a computer method for predicting long-term median transmission loss over 

irregular terrain. The method is applicable for radio frequencies above 20 MHz and may be used 

either with detailed terrain profiles for actual paths or with profiles that are representative of

median terrain characteristics for a given area. Estimates of variability in time and with location, 

and a method for computing service probability, are included.

36
Acoustic methods for remote probing of the lower atmosphere

C. Gordon Little 

 ERL Wave Propagation Laboratory 

Proceedings of the Institute of Electrical and Electronics Engineers, 57(4): 571–578, April 1969 

Significance

The field of radar meteorology was born in the 1950s after researchers realized that radar 

systems developed in WWII were sensitive to precipitation. Research in the 1960s demonstrated 

the usefulness of radar for studying and monitoring precipitation events and the evolution of 

severe storms. However, the potential of acoustic waves for probing the lower atmosphere was 

relatively overlooked. This paper describes for the first time the use of acoustic methods for the 

remote probing of a variety of atmospheric parameters, including wind velocity, temperature and 

humidity structure, and associated turbulence parameters. It opened up a new vein of research 

that eventually led to the development of so-called echo-sounders or sodars (acoustic radars) 

now widely available and used routinely to monitor the lower atmosphere, both in operational 

and research settings. 

Abstract

The potential usefulness of acoustic methods for the remote probing of the lower atmosphere is 

reviewed. Starting with a comparison of the effects of temperature, wind, and humidity 

fluctuations upon the refractive index of air to electromagnetic and acoustic waves, it is shown 

that the fluctuations in acoustic refractive index may be expected to be about 1000 times stronger 

than in the radio case. The opportunities for passive and for line-of-sight remote acoustical 

sensing of the troposphere offered by this relatively strong interaction are briefly discussed. 

Since the scattered power is proportional to the square of the refractive index fluctuations, the 

scatter of acoustic waves may be expected to be roughly one million times stronger than for radio 

waves. Based on the theoretical work of Kallistratova (but including the effects of atmospheric 

absorption), the system parameters required for effective acoustic echo-sounding of the lower 

atmosphere are deduced. It is concluded that the acoustic sounding technique could be developed 

to monitor, to heights of at least 1500 meters, (1) the vertical profile of wind speed and direction, 

(2) the vertical profile of humidity, (3) the location and intensity of temperature inversions, (4) 

the three-dimensional spectrum of mechanical turbulence, and (5) the three-dimensional 

spectrum of temperature inhomogeneity (i.e., of optical refractive index fluctuation). 

Typical time and height resolutions for the proposed acoustic echo-sounders could be of the 

order 10 seconds and 10 meters; the spatial wave number explored could range from about 10-2

m-1 to about 400 m-1. 

37
38
Papers from the 1970s 

A comparison of remote sensing of the clear atmosphere by optical, radio, and acoustic radar 

techniques 

 Vernon E. Derr and C. Gordon Little, 1970 43 

A new method of interpolation and smooth curve fitting based on local procedures 

Hiroshi Akima, 1970 44

Theory of isoperibol calorimetry for laser power and energy measurements 

 E. Dale West and Kenneth L. Churney, 1970 45 

An alternative integral equation for propagation over irregular 

terrain, 2 

Randolph H. Ott, 1971 46 

Miniature ultrasensitive superconducting magnetic gradiometer and its use in 

cardiography and other applications

 James E. Zimmerman and N.V. Frederick, 1971 47 

Modifying the ionosphere with intense radio waves 

 William F. Utlaut and Robert S. Cohen, 1971 48 

Noise thermometry with the Josephson Effect 

 Robert A. Kamper and James E. Zimmerman, 1971 49 

Thermophysical properties of oxygen from the freezing liquid line to 600 R for pressures 

to 5000 Psia 

 Robert D. McCarty and Lloyd A. Weber, 1971 50 

Performance of NBS cryogenic flow research facility 

 J.A. Brennan, Douglas B. Mann, J.W. Dean, and C.H. Kneebone, 1972 51 

Speed of light from direct frequency and wavelength measurements of the methanestabilized laser 

 Kenneth M. Evenson, Joseph S. Wells, F. Russell Petersen, Bruce L. Danielson, 

 Gordon W. Day, Richard L. Barger, and John L. Hall, 1972 52 

Theoretical study of the ionospheric F region equatorial anomaly 

I. Theory 

David N. Anderson, 1973 53 

Thermal conductivity of solids at room temperature and below 

 Greg E. Childs, Lewis J. Ericks, and Robert L. Powell, 1973 54 

39
Generation of standard EM fields using TEM transmission cells 

 Myron L. Crawford, November 1974 55 

International intercomparison of complex permittivity at 9 GHz 

 Howard E. Bussey, Derek Morris, and E.B. Zaltsman, 1974 56 

Man-made radio noise, Part I: Estimates for business, residential, and rural areas 

 Arthur D. Spaulding and Robert T. Disney, 1974 57 

Precipitating electron fluxes formed by a magnetic field aligned potential difference 

David S. Evans, 1974 58 

Theory and application of antenna arrays 

Mark T. Ma, 1974 59 

Studies of winds in the upper troposphere with a sensitive VHF radar 

 John L. Green, James M. Warnock, Richard H. Winkler, 

and Thomas E. VanZandt, 1975 60 

Magnetic suspension densimeter for measurements on fluids of cryogenic interest 

 William M. Haynes, Michael J. Hiza, and Nolan V. Frederick, 1976 61 

Study of weld flaws in the Alaska pipeline: 

1. Evaluation of girth welds from the Trans–Alaska pipeline 

 Richard P. Reed, M. Bud Kasen, Hassel M. Ledbetter, and Harry I. McHenry, 1976 62 

2. A fracture mechanics evaluation of flaws in pipeline girth welds 

 Richard P. Reed, Harry I. McHenry, and M. Bud Kasen, 1979 62 

3. Interim report on the significance of blunt flaws in pipeline girth welds 

 M. Bud Kasen and R.P. Mikesell, 1980 62 

An analysis of three weather-related aircraft accidents 

 Tetsuya T. Fujita and Fernando Caracena, 1977 63 

A network analyzer incorporating two six-port reflectometers 

Cletus A. Hoer, 1977 64 

Definitions of terms for practical superconductors: 

1. Fundamental states and flux phenomena 

 Robert L. Powell and Alan F. Clark, 1977 65 

40
2. Critical parameters 

 Robert L. Powell and Alan F. Clark, 1978 65 

3. Fabrication, stabilization, and transient losses 

 David T. Read, Jack W. Ekin, Robert L. Powell, and Alan F. Clark, 1979 65 

4. Josephson phenomena

 Fred R. Fickett, Steven B. Kaplan, Robert L. Powell, Ray Radebaugh, 

and Alan F. Clark, 1980 65

Effect of stress on the critical current of NbTi multifilamentary composite wire 

Jack W. Ekin, Fred R. Fickett, and Alan F. Clark, 1977 66 

Kinetics of the reaction of HO2 with NO 

 Carleton J. Howard and Kenneth M. Evenson, 1977 67 

Ocean surface currents mapped by radar 

 Donald E. Barrick, Michael W. Evans, and Bob L. Weber, 1977 68 

Optimum reception in an impulsive interference environment 

Part I: Coherent detection 

Part II: Incoherent reception 

 Arthur D. Spaulding and David Middleton, 1977 69 

Applications of closed-cycle cryocoolers to small superconducting devices 

 James E. Zimmerman and Thomas M. Flynn, 1978 71 

Picosecond domain waveform measurements 

Norris S. Nahman, 1978 72

Radiation-pressure cooling of bound resonant absorbers 

 David J. Wineland, Robert E. Drullinger, and Fred L. Walls, 1978 73 

A hybrid of Erlang B and C formulas and its applications 

Martin Nesenbergs, 1979 74 

Mesoanalysis of the Big Thompson storm 

 Fernando Caracena, Robert A. Maddox, Charles F. Chappell, and L. Ray Hoxit, 1979 75 

“Thru-reflect-line”: An improved technique for calibrating the dual six-port 

automatic network analyzer 

 Glenn F. Engen and Cletus A. Hoer, 1979 76 

41
42
A comparison of remote sensing of the clear atmosphere by optical, radio, and 

acoustic radar techniques

Vernon E. Derr and C. Gordon Little 

 ERL Wave Propagation Laboratory 

Applied Optics, 9(9): 1976–1992, September 1970 

Significance

The field of tropospheric remote sensing was relatively new in the 1960s. Radio techniques were 

just beginning to be applied in earnest to probe and monitor severe storms. Optical methods 

based on laser technology invented in the late 1950s were still in their infancy. Two landmark 

studies by Little (1969) and McAllister (1969) had only just outlined the potential of acoustic 

techniques. The authors of the nominated paper noted that the complexity of emerging 

environmental observational needs, from weather prediction to air pollution monitoring, would 

require not one, but a full suite of sensors probing the same atmospheric volume to extract the 

information needed to understand fully the physical processes involved. The authors were the 

first to analyze and highlight the complementary and synergistic nature of radio, optical and 

acoustic radar technologies as applied to the probing of the clear lower atmosphere. Although 

many of the techniques they discuss are not in use today, their notion of combining sensor 

technologies to address critical observational needs is being realized today in the concept of test 

beds and integrated sounding systems. 

Abstract

The considerable utility of ultrasensitive microwave radar in atmospheric studies can now be 

augmented by lidar and acoustic-sensing techniques. The current and potential capabilities, and 

limitations, of these methods of remote atmospheric probing are discussed and the techniques are 

compared. From this analysis the conclusions emerges that a remote sensing facility consisting of 

these instruments probing the same volume of the atmosphere can measure many of the 

meteorologically significant parameters necessary to increase our understanding of the structure 

and dynamics of the clear lower atmosphere, and provide the spatial and temporal density of 

measurements necessary for weather forecasting.

43
A new method of interpolation and smooth curve fitting based on local 

procedures 

Hiroshi Akima

 ERL Institute for Telecommunication Sciences 

Journal of the Association for Computing Machinery, 17(4): 589–602, October 1970 

Significance

Hiroshi Akima, a Japanese mathematician, first came to ITS as an exchange scientist in the 

1960s and then was invited to return as an employee. Akima was a computer enthusiast long 

before computers became commonplace. This paper, published in 1970, describes a clean, neat, 

and very accurate computer method for drawing a smooth curve that joins a set of data points on 

a graph. Before this, the best way to achieve such a curve was for a trained scientist or engineer 

to draw it manually. The method described in the paper proved very popular in a wide range of 

fields, resulting in 344 citations since 1975. 

Abstract 

A new mathematical method is developed for interpolation from a given set of data points in a 

plane and for fitting a smooth curve to the points. This method is devised in such a way that the 

resultant curve will pass through the given points and will appear smooth and natural. It is based 

on a piecewise function composed of a set of polynomials, each of degree three, at most, and 

applicable to successive intervals of the given points. In this method, the slope of the curve is 

determined at each given point locally, and each polynomial representing a portion of the curve 

between a pair of given points is determined by the coordinates of and the slopes at the points. 

Comparison indicates that the curve obtained by this new method is closer to a manually drawn 

curve than those drawn by other mathematical methods. 

44
Theory of isoperibol calorimetry for laser power and energy measurements 

E. Dale West and Kenneth L. Churney 

 NBS Radio Standards Physics Division 

Journal of Applied Physics 41: 2705–2712, 1970 

Significance

This paper addressed the design of calorimeters for the measurement of laser power and energy, 

and provided the theoretical basis for all of the primary laser radiometry standards used by NIST 

today. It was identified as one of the 100 most significant NBS/NIST papers at the centennial 

celebration.

Abstract 

Laser power and energy measurements are commonly made in calorimeters operating in a 

constant temperature environment. Calorimeters of this type are analyzed in terms of the first law 

of thermodynamics and the boundary value problem describing heat flow in the calorimeter. This 

theory of the measurement suggests design features of the calorimeter, sources of error to be 

avoided in design and operation, and tests to demonstrate experimentally the adequacy of the 

design. The analysis shows how time-temperature data can be used to allow for the temperature 

gradient on the calorimeter and the heat exchange due to transients in the temperature.

45
An alternative integral equation for propagation over irregular 

terrain, 2

Randolph H. Ott 

 OT Institute for Telecommunication Sciences 

Radio Science, 6 (4): 429–435, 1971 

Significance

This paper presents an improved derivation for an integral equation for propagation over 

irregular terrain. The integral equation was tested numerically for a spherical earth (where an 

exact solution was available) with excellent agreement. Then a more interesting terrain profile, a 

Gaussian hill, was analyzed, and the solution was compared with George Hufford’s earlier 

(1952—the “alternative” referred to in the title) integral equation and knife-edge diffraction. The 

numerical solutions agreed well and predicted the focusing of the field on the near side of the hill 

and the shadowing on the back side. The computer code Wagner that came out of this 

publication has received extensive use both inside and outside the Boulder Laboratories. 

Abstract 

An integral equation for calculating the attenuation of radio waves propagating over irregular 

terrain is rederived. The integral equation is applied to three terrain profiles, and the solutions are 

compared with solutions obtained by using classical methods such as the residue series and 

diffraction theory. 

46
Miniature ultrasensitive superconducting magnetic gradiometer and its use in 

cardiography and other applications 

James E. Zimmerman and Nolan V. Frederick 

 NBS Cryogenics Division 

Applied Physics Letters, 19: 16–19, 1971 

Significance

The Superconducting QUantum Interference Device or SQUID is a magnetic field sensor so 

sensitive that it is easily overwhelmed by the earth’s weak magnetic field. In 1971, James 

Zimmerman and Nolan Frederick developed a new configuration of the SQUID magnetometer 

that is sensitive only to spatial variations in the magnetic field. Called a gradiometer, their device 

can be used to measure the extremely weak fields associated with the human heart and brain, 

even in the ambient field of the earth. Gradiometers based on their work are now routinely used 

to study noninvasively the neural activity of the brain and even to pinpoint centers of abnormal 

activity in the brains of epileptic patients. 

Abstract 

A portable magnetic gradiometer was built using an rf-biased point contact device as a sensor 

and a superconducting flux transformer 2.5 cm in diameter by 10 cm long to couple to the 

gradient of the external field. The instrument is limited by fluctuations which are probably 

associated with an uneven boiling of the cryogenic liquids and by environmental fluctuations in 

some locations. It is shown that the inherent sensitivity can be increased by an order of

magnitude by increasing the bias frequency from 30 to 300 MHz. A possible use of the 

instrument as a magnetocardiograph in an unshielded environment was demonstrated.

47
Modifying the ionosphere with intense radio waves 

William F. Utlaut 

 OT Institute for Telecommunication Sciences 

Robert S. Cohen 

 Consultant 

 NOAA Aeronomy Laboratory 

Science, 174: 245–254, October 15, 1971 

Significance

Although controversial, the ITS experiments in “ionospheric modification” were actually quite 

benign. The ionosphere (the earth’s upper atmosphere) is important in telecommunications 

because it interacts with radio waves in various, not always predictable, ways. In order to study 

the properties of the ionosphere, high-power transmitters known as “heaters” were constructed 

that could radiate vertical HF beams incident on the ionosphere. These beams would briefly, 

temporarily, “modify” the small section of ionosphere affected, by raising its temperature 

slightly (far less than the sun does every day). At the same time, a probe wave would be sent up 

to record what occurred in the ionosphere during the transmission. One of the first heaters was 

built at the Department of Commerce field site in Platteville, Colorado, and was operated during 

the late 1960s and 1970s. This article describes the work done at Platteville and discusses 

preliminary results. Although ionospheric modification is no longer performed in Colorado, 

these studies laid the groundwork for continuing research of this type in Alaska (HIPAS and 

HAARP), and elsewhere in the world. 

Abstract 

The ionospheric modification experiments provide an opportunity to better understand the 

aeronomy of the natural ionosphere and also afford the control of a naturally occurring plasma, 

which will make possible further progress in plasma physics. The ionospheric modification by 

powerful radio waves is analogous to studies of laser and microwave heating of laboratory 

plasmas (20). “Anomalous” reflectivity effects similar to the observed ionospheric attenuation 

have already been noted in plasmas modulated by microwaves, and anomalous heating may have 

been observed in plasmas irradiated by lasers. Contacts have now been established between the 

workers in these diverse areas, which span a wide range of the electromagnetic spectrum.

Perhaps ionospheric modification will also be a valuable technique in radio communications. 

48
Noise thermometry with the Josephson effect 

Robert A. Kamper and James E. Zimmerman 

 NBS Cryogenics Division 

Journal of Applied Physics, 42: 132–136, 1971 

Significance

Only a few thermal effects are understood sufficiently well that they can be used as a absolute 

measure of temperature. In 1971, Robert Kamper and James Zimmerman proposed and 

demonstrated a new absolute thermometer based on the intrinsic electrical noise of a resistor. 

This noise, known as Johnson noise, depends only on the resistance, the temperature, and a 

fundamental constant of nature called Boltzman’s constant. Using a sensitive superconducting 

amplifier, Kamper and Zimmerman were able to measure the Johnson noise of a resistor at 

temperatures near absolute zero and establish a new method of thermometry. Noise thermometry 

has since played an important role in establishing the temperature scale in this low-temperature 

regime. 

Abstract 

Thermal noise causes a random frequency modulation of the self-oscillation of a Josephson 

junction, and the temperature of the noise source can be determined by analysis of the generated 

signal. We show that a thermometer based on this principle would be theoretically capable of 

measuring temperatures in the microkelvin range, and describe a prototype thermometer which 

has recorded noise temperatures down to 0.075 K. 

49
Thermophysical properties of oxygen from the freezing liquid line to 600 R 

for pressures to 5000 Psia 

Robert D. McCarty and Lloyd A. Weber 

 NBS Cryogenics Division 

NBS Technical Note 384, 1971 

Significance

The National Bureau of Standards was well known for its properties studies—comprehensive 

and integrated projects of experimental measurement, data collection and evaluation, model 

development, and finally dissemination of standard values. After the initial work in Boulder on 

hydrogen, the mandate of the organization was broadened, and this early work on oxygen 

(continuing the trend in both cryogenics and challenging materials handling issues) represents 

one of the earliest efforts on property dissemination. The form of this technical note, page upon 

page of tabular material, represents the canonical output of the 1970s. Of course, such paper 

tables have been superceded by computer programs and web-based information sources, and the 

technical information has also been refined and updated. However, the numbers in this technical 

note went into the design of the important propulsion systems of the day (the oxygen tanks and 

technologies on NASA rockets relied on these property data), and this publication was the first in 

an important series of property standards. 

Abstract

Tables of thermophysical properties of oxygen are presented for temperatures from the melting 

line to 600 R for pressures to 5000 psia. The tables include, entropy, enthalpy, internal energy, 

density, volume, speed of sound, specific heat, thermal conductivity, viscosity, thermal 

diffusivity, Prandtl number and the dielectric constant for 79 isobars. Also included in the 

isobaric tables are quantities of special utility in heat transfer calculations: (∂P/∂V)T, (∂P/∂T)ρ, 

V(∂H/∂V)P, V(∂P/∂U)V, –V(∂P/∂V)T, l/V(∂V/∂T)P. 

In addition to the isobaric tables, tables for the saturated vapor and liquid are given which 

include all of the above properties, plus the surface tension. Tables for the P-T of the freezing 

liquid, index of refraction and the derived Joule–Thomson inversion curve are also presented. 

The specific heat of the saturated liquid is given in graphical form. A temperature-entropy chart 

and a Mollier diagram are also included. 

50
Performance of NBS cryogenic flow research facility 

J.A. Brennan, Douglas B. Mann, J.W. Dean, and C.H. Kneebone 

 NBS Cryogenics Division 

Advances in Cryogenic Engineering, Vol. 17, Plenum Press, NY, 199–205, 1972 

Significance

The cryogenic flow research facility, now known as the “flow loop,” has been housed in 

Building 3 on the Boulder campus for some 40 years. This unique facility—the only source of 

cryogenic flow calibrations in North America—is the connection between NIST standards and 

such diverse activities as measuring the amounts of cryogenic fuels in the space program and 

certifying the quantity of liquid nitrogen sold to hospitals. This paper provides an early 

performance assessment of the flow loop, and is the predecessor to the current uncertainty 

evaluations in flow metering. Although many components of the flow loop have been updated, 

this paper serves as a reference to the early protocols in cryogenic flow measurement. 

Abstract (As the paper has no abstract, the introduction is given here) 

The historical background and design of the Cryogenic Flow Research Facility have been given 

previously by Dean et al. This report describes the present status of knowledge with respect to 

performing cryogenic flow measurements after a year of operation of the facility. The sources of 

error presented here details just the contribution of the flow facility itself to the uncertainty of

flow measurements. Subsequent reports will deal with the problems and uncertainties in using 

the facility in research measurements and in evaluation of flowmeters. The uncertainties given 

here are limits to the discrimination possible in these subsequent investigations. 

51
Speed of light from direct frequency and wavelength measurements of the 

methane-stabilized laser 

Kenneth M. Evenson, Joseph S. Wells, F. Russell Petersen, Bruce L. Danielson, Gordon W. Day, 

Richard L. Barger, and John L. Hall 

 NBS Quantum Electronics Division 

Physical Review Letters 29: 1346–1349, 1972 

Significance

This paper is one of the most important papers related to lasers, not only providing a new and 

100-fold improvement in the determination of the speed of light, but leading directly to the 

redefinition of the meter. It was identified as one of the 100 most significant NBS/NIST papers 

at the centennial celebration. 

Abstract 

The frequency and wavelength of the methane-stabilized laser at 3.39 μm were directly measured 

against the respective primary standards. With infrared frequency synthesis techniques, we 

obtain ν = 88.376 181 627 (50) THz. With frequency-controlled interferometry, we find λ = 

3.392 231 376 (12) μm. Multiplication yields the speed of light c = 299 792 456.2 (1.1) m/sec, in 

agreement with and 100 times less uncertain than the previously accepted value. The main 

limitation is asymmetry in the krypton 6057-Å line defining the meter. 

52
Theoretical study of the ionospheric F region equatorial anomaly 

I. Theory

David N. Anderson 

 NOAA/CIRES 

Planetary and Space Science, 21: 409–419, 1973 

Significance

Prior to the publication of this paper, significant observed longitudinal differences in the low 

latitude ionosphere could not be explained theoretically. Incorporating into a model, complex 

transformation techniques that realistically reproduced the Earth’s geomagnetic field, the paper 

demonstrated that this one unifying coordinate system for both magnetic and electric fields was 

sufficient to account for the longitude variability in the low latitude ionosphere. The model 

described here theoretically solves the time dependent, coupled ion continuity and momentum

equations in the equatorial F region ionosphere and provides ion and electron densities as a 

function of altitude, latitude and local time. This was the first time that a realistic geomagnetic 

field (represented by Euler potentials) had been included in a time dependent ionospheric model. 

This model has been the basis for a number of wide-ranging studies over the last three decades, 

on topics including: (a) ionosphere/neutral wind effects, (b) F-region ionospheric storm effects, 

(c) motion of depleted plasma flux tubes in the equatorial ionosphere, (d) generation of high 

latitude polar cap patches of ionization and, more recently, (e) data assimilation techniques as 

inputs to a Global Assimilation of Ionospheric Measurements (GAIM) model. 

Abstract 

When observed noontime values of the maximum electron density, NNAX(F2) in the 

ionospheric F2 region are plotted as a function of magnetic latitude, a curve is produced which 

has two peaks, one on either side of the dip equator at ±16o dip equator. This paper theoretically 

investigates the daily variation of this latitudinal distribution of NMAX(F2) (the so-called 

Appleton or equatorial anomaly) and specifically attempts to account for the longitudinal 

differences observed between the American and Asian sectors. 

Part I outlines the theory involved in solving the time-dependent plasma continuity equation in 

which production, loss, and transport of ionization are taken into account, where the effects of 

neutral wind, ambipolar diffusion and ExB drift are included in the transport term. By describing

the geomagnetic field in two equivalent ways, B = –L( and B = L" × L$, where ", $ and ( are 

known magnetic scalar potentials, the spherical r, θ and N space coordinates of the continuity 

equation are transformed to coordinates which define directions parallel and perpendicular to the 

magnetic field thus putting the equation in a form suitable for numerical integration.

53
Thermal conductivity of solids at room temperature and below

Greg E. Childs, Lewis J. Ericks, and Robert L. Powell 

 NBS Cryogenics Division 

NBS Monograph 131, 1973 

Significance

This monograph presents graphs of most of the published data at that time on the thermal 

conductivity of most solids of interest to scientists and engineers for temperatures below room

temperature. This 608-page monograph provides very valuable data for the design of any 

cryogenic equipment. Such data was scattered throughout the literature before that time and 

difficult for most researchers to find. Because of the popularity of this monograph it soon 

became out of print. Such a monograph as this was needed at a time before such information 

could be made available electronically. 

Abstract 

An extensive compilation is given of the measured values of thermal conductivity for nearly all 

solid materials from room temperature down to 0.02 kelvin. The reviewed materials include 

elements, alloys and commercial metals, semiconductors, semimetals, ionic and valence crystals, 

minerals, molecular crystals, polymers, glasses, and disordered dielectrics. Excluded are foams, 

powders, earths, fibers, layers of composites, and similar other heterogeneous solids. Data for 

temperatures below 1 kelvin are presented separately. The tables and graphs are complete for 

literature references from 1900 to mid-1971. Experimental methods and physical phenomena are 

discussed in the text and coded in the tables for references for which curves are shown.

54
Generation of standard EM fields using TEM transmission cells 

Myron L. Crawford 

 NBS Electromagnetic Fields Division 

IEEE Transactions on Electromagnetic Compatibility, EMC-16(4): 189-195, November 1974

Significance

This paper describes the use of the transverse electromagnetic (TEM) mode in an expanded 

transmission line to generate a known electromagnetic (EM) field for probe calibration and the 

immunity testing of devices. This paper is basis for the development of TEM cells as 

electromagnetic compatibility (EMC) test device. TEM cells have become a standard tool at 

NIST and in the EMC community. Numerous standards based on TEM cells have been written 

covering tests for immunity, emissions, automotive components, probe calibrations, and 

biological effects. Many in the EMC community still refer to TEM cells as “Crawford Cells” in 

recognition of Crawford’s role in pioneering this methodology. 

Abstract 

A new technique developed at the National Bureau of Standards (NBS) for establishing standard,

uniform, electromagnetic (EM) fields in a shielded environment is described. The technique 

employs transverse electromagnetic (TEM) transmission cells that operate as 50 Ω impedancematched systems. A uniform TEM field is established inside a cell at any frequency of interest 

below that for which higher order modes begin to propagate. Standard field strength levels from

10 μV/m to 500 V/m can be established with uncertainties of less than 1.0 dB to 2.0 dB inside 

the NBS cells for frequencies from dc to 500 MHz. The cells are especially useful for calibrating 

EM radiation hazard meters, for emission and susceptibility testing of small to medium sized 

equipment, and for special low level calibration of very sensitive field strength meters. 

55
International intercomparison of complex permittivity at 9 GHz 

Howard E. Bussey 

 NBS Electromagnetics Division 

Derek Morris 

 National Research Council of Canada 

E.B. Zaltsman 

 Gosstandart, USSR 

IEEE Transactions on Instrumentation and Measurements, IM-23: 235–238, 1974 

Significance

This paper summarizes the measurement results of the international intercomparison between the 

NBS, National Research Council, Canada, and the All-Union Scientific-Research Institute of 

Physico-Technical and Radio-Technical Measurements (VNIIFTRI) USSR. This project 

provided a much needed check on the calculation of permittivity throughout the world. The 

materials used were easily available so it allowed other researchers to compare their results. 

Abstract 

Dielectric constant and loss measurements made by three government laboratories (of the USSR, 

Canada, and the U.S.A.) are compared. The two materials measured were glasses. The 

measurements utilized cavity resonators in the H01n mode. The errors in dielectric constant 

reported by the laboratories were usually ±0.3 percent; actual differences between laboratories of

the average corrected results were only ±0.05 percent. The loss tangent results disagreed when 

multimoding occurred; however, the errors may be as low as ±0.00002 or ±3 percent, whichever 

is the larger, if multimoding is avoided. 

56
Man-made radio noise, Part I: Estimates for business, residential, and rural 

areas 

Arthur D. Spaulding and Robert T. Disney 

 OT Institute for Telecommunication Sciences 

OT Report 74–38, June 1974 

Significance

This report is a description of a comprehensive effort by the Institute for Telecommunication 

Sciences to measure and analyze man-made radio noise in business, residential, and rural areas. 

The measurements were comprehensive in that they included approximately 30 locations in each 

of the areas and 10 frequencies separated approximately by octaves and ranging from 250 KHz 

to 250 MHz. The analysis was also comprehensive in that it included the characterization of the 

variability of the measured parameters over frequency, widely spaced locations, and time withinthe-hour. Part II of this report (OT Report 75-63, published in May 1975), is an equally 

comprehensive bibliography of noise measurement data, applications, and methods. Intended to 

be read by a non-mathematician audience, the material in this report is still very useful today. 

Ultimately, results from this work were used as a world standard in the International Radio 

Consultative Committee (CCIR), the predecessor standards body of the International 

Telecommunication Union. 

Abstract 

The Office of Telecommunications, Institute for Telecommunication Sciences (OT/ITS), over 

the past several years, has accumulated a data base of man-made radio noise measurements in the 

frequency range from 250 kHz through 250 MHz taken in a number of geographical areas. This 

data base has been analyzed to provide estimates of the expected characteristics of man-made 

radio noise in business, residential, and rural areas. The parameters used are the average 

available power spectral density, the ratio of the rms to the average voltage of the noise

envelope, and the ratio of the rms to the average logarithm of the envelope voltage. The variation 

of these parameters as a function of frequency, location, and time are shown and discussed. 

Examples of amplitude and time statistics of the received man-made radio noise process also are 

shown and discussed. The use of the estimates is shown (principally by references in Part II, 

Bibliography) in the solution of problems encountered in frequency management and 

telecommunication system design. 

57
Precipitating electron fluxes formed by a magnetic field aligned potential 

difference

David S. Evans 

 NOAA Space Environment Laboratory 

Journal of Geophysical Research, 79: 2853, 1974 

Significance

This paper, literally overnight, rendered a hitherto unacceptable explanation for aurora entirely 

credible. The paper did so by modeling the consequences of assuming that only the unacceptable 

explanation (electrons energized through an electrical potential established parallel to the 

geomagnetic field) was true and then demonstrating that the modeled consequences agreed in 

great detail with observations. To gain agreement with only a single assumption is an example of 

Occam’s Razor principle so cherished by scientists: the theory that explains the most 

observations by using the fewest assumptions must be the most correct. 

While before 1974 electrical potential differences along the geomagnetic field had been proposed 

to account for the energization of auroral electrons, the suggestion had been almost universally 

discarded on the basis of both theoretical arguments and features in the auroral electron

distribution thought to be inconsistent with acceleration through a potential difference. This 

paper modeled the expected energy distribution of electrons accelerated through a potential 

difference, taking into account the role of backscattered and secondary electrons produced from

the atmosphere. The modeled distribution both naturally accounted for features and agreed with 

actual observations. The paper made the idea of charged particle acceleration through magneticfield aligned potential respectable, and thus stimulated a great deal of work on the origin of such 

an electric field geometry. Since publication, the paper has been cited 287 times in the literature;

47 times since 1998, attesting to its long-lived impact on the field of auroral physics. 

Abstract

A model is developed in which a magnetic field aligned potential difference is assumed to 

accelerate electrons downward into the atmosphere. It is pointed out that the upgoing 

backscattered electrons produced by this electron beam may process insufficient kinetic energy 

to overcome the hypothetical potential difference. These electrons will be reflected downward to 

appear as members of a precipitating electron population. A numerical model was constructed in 

order to describe the total precipitating electron flux in terms of a primary accelerated beam and 

backscatter from the atmosphere. It is pointed out that many features that appear in the model are 

observed in the auroral electron beam as well. An example of an auroral beam, measured by 

Frank and Ackerson (1971), is compared favorably with a model electron beam formed by a 

parallel potential. 

58
Theory and application of antenna arrays 

Mark T. Ma

 OT Institute for Telecommunication Sciences, and 

 University of Colorado 

New York: John Wiley & Sons, Inc., 1974 

Significance

In addition to standard array theory for one- and two-dimensional arrays of point sources in free 

space, this book includes the effects of lossy ground and real antennas, making it useful in 

determining the effects of ground losses and reflections. It also allowed the inclusion of mutual 

coupling effects. Practical antenna arrays, such as Yagi–Uda antennas and log-periodic dipole 

arrays, were treated in detail along with numerical results. Traveling-wave antennas, such as the 

sloping vee, sloping rhombic, and side-terminated vertical half-rhombic antennas, were also 

analyzed. The numerical results and elegant mathematics combine to make this book still useful 

to both engineers and theoreticians. 

Abstract 

Chapter 1 introduces the reader to the fundamentals of linear arrays of discrete elements. It starts 

with the analysis for simple uniform arrays and then proceeds to arrays with tapered amplitudes, 

phases, and spacings. A relatively new approach, using finite Z-transforms for analyzing arrays 

with nonuniform amplitude excitations, is presented in detail with illustrative examples. 

Difference patterns produced by a monopulse array are also formulated and studied. Chapter 2 

offers many recently developed techniques for synthesizing various linear arrays. It is here that 

power and field patterns are equally emphasized. Considerable effort is devoted to the 

understanding of arrays with equal sidelobes. In addition to the synthesis of array patterns, 

optimization of the array directivity is also thoroughly discussed. As an extension to the material 

presented in the first two chapters, both analysis and synthesis of two-dimensional arrays are 

given in Chapter 3. Greater attention is placed on ring and elliptical arrays.

In Chapter 4, currents, impedances, fields, and power gains for simple antennas such as dipoles, 

monopoles, and sleeve antennas above lossy ground are presented in detail. Equal attention is 

also given to arrays of these antennas in the form of the Yagi–Uda antenna, the curtain array, or 

the Wullenweber antenna. The basic principle and analytical formulation for a class of 

broadband antennas, namely, the log-periodic dipole array above lossy ground, are given in 

Chapter 5. Placing this array in alternative geometric positions (relative to the ground) to yield 

maximum radiations at low or high angles from the ground plane is also explored for different 

possible applications. In Chapter 6, a few commonly used traveling-wave antennas above lossy 

ground are analyzed. 

59
Studies of winds in the upper troposphere with a sensitive VHF radar

John L. Green, James M. Warnock, Richard H. Winkler, and Thomas E. VanZandt 

 NOAA Aeronomy Laboratory 

Geophysical Research Letters, 2(1): 19–21, 1975 

Significance

This paper announces the development of the forerunner of the wind-profiling radar used widely 

today for studying winds in the troposphere (lower atmosphere) and above. By the late 1960s, 

researchers had noted that as radar waves propagate through the atmosphere, part of their energy 

is reflected back to the radar instrument, even in clear air. Researchers proposed that these 

echoes might be used as a measure of the wind speed in the atmosphere, because of the 

measurable change in the echo caused by having been reflected off a moving parcel of air (the 

“Doppler” effect). Some early studies made with existing large radars indicated that the approach 

had promise. But Aeronomy Lab scientists set out to design and build a radar specifically for 

wind measurements. It was located at Sunset, Colorado, in the foothills near Boulder. This paper 

announces their success and presents their first data gathered on lower-atmosphere winds. They 

compare the radar measurements with measurements made from balloon-borne instruments (the 

method used by meteorologists at that time). The results confirmed that the radar technique was a 

viable new method of obtaining wind data in the lower atmosphere. 

The new technique offered a “quantum leap” in meteorological capabilities, permitting a much 

higher cadence of observations than balloons. Later research led to wind profilers that can 

operate unattended in remote locations. Aeronomy Lab partnerships with scientists in NOAA’s 

former Wave Propagation Lab (now Environmental Technology Lab) helped to transition the 

wind profiling technology into operational use, and the Forecast Systems Lab developed the 

NOAA Profiler Network in the late 1980s and early 1990s. Wind-profiling radars are a 

fundamental tool in today’s meteorological science and weather forecasting. 

Abstract

A large 40.475 MHz Doppler radar has been constructed near Sunset, Colorado, 16 km west of 

Boulder, in order to study winds, the troposphere, stratosphere, and mesosphere. Early results 

from the troposphere are presented here. It is concluded that: (1) With a sensitive VHF radar it is 

possible to detect echoes from throughout the upper troposphere almost all the time, under both 

clear and cloudy conditions; (2) Horizontal winds derived from the Doppler shifts of the echoes 

are consistent at heights more than 2 km above the local terrain with rawinsonde winds measured 

over 55 km away; (3) The reflectivity of the scatterers in the troposphere is not strongly aspect 

sensitive, up to an angle of 30° from the zenith. 

60
Magnetic suspension densimeter for measurements on fluids of cryogenic 

interest 

William M. Haynes, Michael J. Hiza, and Nolan V. Frederick

 NBS Institute for Basic Standards, Cryogenics Division 

Review of Scientific Instruments 47(10): 1237–1250, 1976 

Significance

The use of Archimedes’ principle to measure the density of fluids certainly has a long history, 

but the use of magnetic suspensions to isolate the force determination from the system being 

studied is more recent, with much of the technology having been developed at the Boulder 

Laboratories. The use of large-scale liquefaction and global commerce in cryogenic natural gases 

(LNG) has made the density metrology for such cryogenic systems of great importance. The 

apparatus described in this paper was used to provide accurate, consistent, and comprehensive 

density data for liquefied natural gas mixtures. It could operate over a wide range of temperature 

and pressure with the precision and accuracy in the measurements required for anticipated 

technical applications. The uncertainty assessments that comprise a major part of this paper have 

tied commerce in LNG to fundamental NIST measurement standards. 

Abstract 

An apparatus incorporating a magnetic suspension technique has been developed for density 

measurements on liquids and liquid mixtures, particularly at saturation, at temperatures between 

90 and 300 K and at pressures to 5 MPa (approximately 50 atm). The feasibility of adapting this 

method, previously used at room temperature, for low temperature use had been demonstrated in 

an earlier study with a density measurement on saturated liquid nitrogen near its normal boiling 

point. The present apparatus, which is significantly improved, and in most respects different 

from the earlier model, is described in detail. It includes a cryostat for continuous wide-range 

temperature control, a windowed equilibrium cell particularly suited for studies of liquid 

mixtures, and a new electronic servocircuit with a linear differential transformer for position 

control of the magnetic buoy. Extensive tests and density measurements have been carried out to 

evaluate the performance of this apparatus. Densities of saturated liquid nitrogen between 95 K 

and 120 K and saturated liquid methane between 105 K and 160 K are reported. The estimated 

standard deviation of a single density measurement is less than 0.02 %. The total systematic error 

in the measurement process from known sources is approximately 0.05 %. The total uncertainty 

of a single density measurement, which is taken as three times the standard deviation plus the 

systematic error, is approximately 0.1 %. Comprehensive comparisons of the present results with

previous experimental data are presented. 

61
Study of weld flaws in the Alaska pipeline: 

1. Evaluation of girth welds from the Trans–Alaska pipeline 

Richard P. Reed, M. Bud Kasen, Hassel M. Ledbetter, and Harry I. McHenry 

 NBS Fracture and Deformation Division 

Second Report to the Office of Pipeline Safety Operations, September 29, 1976 

2. A fracture mechanics evaluation of flaws in pipeline girth welds 

Richard P. Reed, Harry I. McHenry, and M. Bud Kasen 

 NBS Fracture and Deformation Division 

Welding Research Council Bulletin 245, 1979 

3. Interim report on the significance of blunt flaws in pipeline girth welds 

M. Bud Kasen and R.P. Mikesell 

 NBS Fracture and Deformation Division 

Proceedings, International Conference on Pipeline and Energy Plant Piping, Calgary, Alberta, 

Canada, November 10–13, 1980 

Significance

The Alaska pipeline was constructed of 1.22 m diameter steel pipe sections that were joined in 

the field by manual welding. Construction was subject to various commercial and federal codes, 

with relatively conservative acceptance criteria, which prescribed radiographic inspection of the 

girth (end-to-end) joints. The inspection included a quick evaluation during construction, and 

some later reexamination. As the pipeline approached completion, the reevaluation revealed 

flaws which may have exceeded the weld-quality standards. Some were in locations where the 

pipeline passed under rivers or were in other environmentally sensitive areas, where an 

unnecessary repair could cause more harm to the environment or the pipeline. The Office of 

Pipeline Safety Operations asked NBS to help evaluate the suspect welds based on the actual 

service requirements. 

NBS used a fracture mechanics approach to determine whether the flaws shown by the 

radiographs would affect the fitness-for-service of the pipeline, using the actual pipeline 

pressures, operating temperatures, and material properties, rather than the conservative 

approximations built into the construction codes. In addition, NBS tested pipeline sections with 

flaws under simulated service conditions and was able to develop techniques to estimate flaw 

depths from the radiographs. This was the first use of fracture mechanics to evaluate the 

significance of flaws in pipeline girth welds. They showed that this material was highly resistant 

to brittle fracture from these blunt flaws under realistic pipeline operating conditions (and so was 

safe to operate), but cautioned that further work was needed to assess the long-term effects of 

stress corrosion. 

62
An analysis of three weather-related aircraft accidents 

Tetsuya T. Fujita 

 Department of the Geophysical Sciences, University of Chicago 

Fernando Caracena 

 NOAA Atmospheric Physics and Chemistry Laboratory 

Bulletin of the American Meteorological Society, 58: 1164–1181, 1977 

Significance

This paper is a historical landmark in both meteorology and air safety. Fujita had earlier 

identified what he hypothesized as wind damage footprints of severe downdrafts (later termed 

microbursts) in his areal storm damage studies. He showed the plausibility of downbursts as a 

threat to aviation in a companion paper Fujita and Beyers (1977): Spearhead echo and 

downbursts in the crash of an airliner. Mon. Wea. Rev., 105, 129–146. However, his hypothesis 

remained controversial until this paper. Working independently, Dr. Fernando Caracena had 

collected and analyzed data from wind towers and other pressure and temperature sensors that 

constituted a de facto meteorological mesonetwork surrounding the crash site of Continental 

flight 426 on 7 August 1975. Dr. Caracena’s definitive analysis (NTSB exhibit No. 5E-1 of the 

Stapleton Accident, Washington, D.C., 12 pp.) led the National Transportation Safety Board to 

conclude that this accident was the result of windshear. Caracena brought the critical piece of 

evidence to Fujita’s downburst hypothesis, which definitively showed that not only could 

cumulus convection result in downdraft-induced, damaging winds, but that such a phenomenon 

could also bring down a modern jetliner. This paper paved the way for many followup studies 

and field projects, which resulted in the construction of Terminal Doppler Radars at major 

airports and new pilot training programs. Consequently, since 1994, there have been no air 

disasters in the United States attributable to microbursts. 

Abstract 

Two aircraft accidents in 1975, one at John F. Kennedy International Airport in New York City 

on 24 June and the other at Stapleton International Airport in Denver on 7 August, were 

examined in detail. A third accident on 23 June 1976 at Philadelphia International Airport is 

being investigated. Amazingly, there was a spearhead echo just to the north of each accident site. 

The echoes formed from 5 to 50 min in advance of the accident and moved faster than other 

echoes in the vicinity. These echoes were photographed by National Weather Service radars, 

130–205 km away. At closer ranges, however, one or more circular echoes were depicted by 

airborne and ground radars. These cells were only 3–5 km in diameter, but they were 

accompanied by downdrafts of extreme intensity, called downbursts. All accidents occurred as 

aircraft, either descending or climbing, lost altitude while experiencing strong wind shear inside 

downburst cells. 

63
A network analyzer incorporating two six-port reflectometers 

Cletus A. Hoer 

 NBS Electromagnetics Division 

IEEE Transactions on Microwave Theory and Techniques, MTT-25(12): 1070–1074, 

December 1977 

Significance

This paper by Cletus Hoer was the first publication that described the dual six-port technique for 

making network analyzer measurements. The dual six-port network analyzer, used to measure 

broadband (2–18 GHz), complex input and output wave variables from any linear, reciprocal 

two-port circuit, was a significant advancement to the microwave industry in that it provided a 

simpler and more accurate method for measuring complex scattering parameters and power. The 

instrument described here provides calibration capabilities superior to commercially available 

four-port network analyzers, since its measurement “heads” may be connected directly to a 

device-under-test without connecting cables. The dual six-port network analyzer has been used 

as a calibration tool in many national metrology laboratories and universities. It has also been the 

subject of many publications both nationally and internationally since its invention in 1977. The 

dual six-port continues to be a significant invention in that it provides a simple technique for 

building a microwave network analyzer. The technique is still viable today particularly for 

measurements at millimeter and higher frequencies. This instrument is still the national standard, 

in use in the Electromagnetics Division to calibrate circuits and devices for U.S. industry. 

Abstract 

This paper outlines the theory and design of a microwave network analyzer capable of measuring 

the network parameters of any linear reciprocal or nonreciprocal, active or passive two port. An 

RF signal from one source is applied at the same time to two six-port reflectometers which 

measure the incident and reflected waves at the ports of the two port being measured. An 

experimental dual six-port network analyzer for the 2 to 18 GHz range has been completed and is 

described briefly. Some advantages of the proposed design over existing network analyzer 

designs are (1) only one source is needed, (2) no phase detectors are required, (3) no flexible 

cables or arms are used between the reflectometers and the two port being measured, and (4) 

self-calibration techniques are readily applied. 

64
Definitions of terms for practical superconductors: 

 NBS Thermophysical Properties Division 

1. Fundamental states and flux phenomena 

Robert L. Powell and Alan F. Clark 

Cryogenics 17(12): 697–701, December 1977 

2. Critical parameters 

Robert L. Powell and Alan F. Clark 

Cryogenics 18(3): 137–41, March 1978 

3. Fabrication, stabilization, and transient losses 

David T. Read, Jack W. Ekin, Robert L. Powell, and Alan F. Clark 

Cryogenics 19(6): 327–32, June 1979 

4. Josephson phenomena 

Fred R. Fickett, Steven B. Kaplan, Robert L. Powell, Ray Radebaugh, and Alan F. Clark 

Cryogenics 20: 319–25, June 1980 

Significance

This sequence of four articles defined for the first time in a physically accurate and meaningful 

way all of the terms used in superconductivity. Practical superconductors were first developed in 

the late 1960s and were only beginning to find applications in the mid-1970s. The strong low 

temperature background and early studies of superconductivity in the Cryogenics Division 

enabled the authors of these works to develop the sound basis needed for the development of 

measurements and standards in this rapidly growing field. The complete set of definitions was 

adopted by the then new ASTM Committee on Superconductivity as their first standard and led 

to several continuing efforts to ease the applications of practical superconductors into the 

marketplace. These efforts continue to this day, developing measurement techniques for new 

products and applications of superconductivity. The standardization efforts now involve the 

International Standards Organization in which NIST staff still play a key role. 

Abstract 

The definitions of terms used in describing the phenomenology and measurement practices of 

practical superconductive materials are proposed. The definitions cover the subject categories of: 

1, fundamental states and flux phenomena; 2, critical parameters; 3, fabrication, stabilization, 

and transient losses; and 4, Josephson phenomena. It is intended that these terms will become the 

basis for the development of standard measurement practices and responses are invited. 

65
Effect of stress on the critical current of NbTi multifilamentary composite 

wire 

Jack W. Ekin, Fred R. Fickett and Alan F. Clark 

NBS Thermophysical Properties Division 

Advances in Cryogenic Engineering, Vol. 22, New York: Plenum Press, 449–452, 1977 

Significance

The practical applications of superconducting wires and the first functional superconducting 

magnets made from those wires were having frequent failures in the early 1970s. The staff of the 

Cryogenics Division, having experience in low temperature research, the mechanical properties 

of structural materials, and the electrical properties of superconductors, concluded that there 

must be a mechanical/electrical interaction. Starting with a superconducting wire wrapped 

around a piece of broom handle inserted into the grip of a low temperature tensile test machine, 

they initiated one of the longest running research programs at NBS/NIST. This publication is the 

report of the first observation of the effect of stress on the critical current in superconductors, 

demonstrating that the ability of a superconductor to carry electrical current without resistance is 

degraded when the conductor is under stress. Subsequent programs studied both tensile and 

compressive stress in superconducting wires, cables, composites, and magnet structures and 

discovered patterns of uniform behavior and scaling laws. These now allow both understanding 

of the fundamental physics of the effect as well as sophisticated engineering design. 

Abstract (As the paper has no abstract, a portion of the introduction is given here) 

....Typically, data on the critical-current characteristics of superconducting composites are 

obtained on wires that are in an unstressed state. Very little is known, however, about how the 

critical current behaves in wires experiencing stresses of the type described above. To measure 

these effects, short sample critical-current tests were made under conditions simultaneously 

simulating the mechanical and magnetic environments of high-field superconducting magnets. 

The program was initiated both to form a basis for the fundamental understanding of stress 

effects on superconductor stability and to provide engineering data for optimizing design and 

construction of high-field magnets. As will be seen, the preliminary results indicate that NbTi 

multifilamentary superconducting composite wires are not characterized by a single critical 

current vs. field curve, but rather by a family of curves, each corresponding to a different 

operating stress level. 

66
Kinetics of the reaction of HO2 with NO

Carleton J. Howard 

 NOAA Aeronomy Laboratory 

Kenneth M. Evenson 

 NBS Time and Frequency Division

Geophysical Research Letters, 4(10): 437–440, 1977 

Significance

This paper by Howard and Evenson studied what is perhaps the “linchpin” reaction in the lower 

atmosphere—the reaction of hydroperoxyl radicals (HO2) with nitric oxide (NO). These two very 

reactive and naturally occurring species are present in the atmosphere in trace amounts, yet they 

have a disproportionately large effect on the production of ozone in the atmosphere’s protective 

stratospheric ozone layer. Their reaction makes nitrogen dioxide (NO2), which almost 

immediately breaks down in sunlight to make ozone. Thus, the reaction of HO2 with NO is, in 

essence, an ozone-making machine in the atmosphere. Before Howard and Evenson’s work, the 

rate of the reaction had only been estimated by indirect means, and the best estimate was too 

slow to explain the amount of ozone that was present in the atmosphere. Howard and Evenson 

set out to make the first direct measurement of the reaction’s rate. The experiment was tricky, 

because of the extreme reactivity of the HO2 with the surfaces of the experimental apparatus. 

They found a value about 10 times faster than the earlier estimates. This finding has withstood 

the test of time, and remains the recommended value for the rate of the reaction. This work 

enabled atmospheric scientists to reconcile models of atmospheric chemistry with real-world 

measurements, thus providing a more accurate rendering of ozone chemistry to underpin 

decisions on the ozone layer, as well as “smog” chemistry. For example, the new understanding 

implied that industrially produced chlorofluorocarbons (CFCs) were even more important at 

depleting the ozone layer than previously thought. That insight served as input to the 

international decisions made later to ban the production of CFCs. 

Abstract

The gas phase reaction of HO2 radicals with NO was studied using a discharge-flow system and 

laser-magnetic resonance detection. Concentrations of HO2 down to 2 × 109

 molecules/cm3 were 

detectable, thus allowing the reaction to be studied under pseudo-first-order kinetic conditions. 

The rate constant was measured using three independent kinetic schemes, one of which involved 

the detection of the reaction products OH and NO2. The three schemes gave results in excellent 

agreement. The rate constant, k1, for the reaction HO2 + NO 6 OH + NO2 is (8.1 ± 1.5) 5 10-12

cm3

/molecule@s at 296 K and a pressure of 140 to 220 Pa (1.1 to 1.7 torr). The measurements also 

indicate that the rate constants for two other exothermic channels of the reaction are less than 2%

of k1. 

67
Ocean surface currents mapped by radar

Donald E. Barrick, Michael W. Evans, and Bob L. Weber 

 NOAA Wave Propagation Laboratory 

Science, 10(4313): 138–144, October 14, 1977 

Significance

An accurate knowledge of surface currents is critical for the sound management of our coastal 

waters. It aids emergency managers by helping them to predict the drift of surface pollutants; it is 

of interest to ocean biologists because it is an important factor in determining the distribution of 

near-surface zooplankton and phytoplankton, which are critical components of the ocean food 

chain; and it benefits the fisheries industry by providing a better insight into the drift of many 

types of fish eggs. Surface currents also transport water with anomalous temperature differences 

that can impact regional weather patterns. Prior to the 1970s, the measurement of surface 

currents was accomplished via moored current meters, or by tracking floating objects or material 

suspended in the flow. These methods were often expensive and time intensive, and did not 

always yield current maps with the required spatial and temporal resolution. 

The nominated paper describes the first successful effort to remotely map surface currents over a 

large area (out to 70 km from shore) using a relatively inexpensive and compact shore-based 

radar system that offered continuous, unattended operation. It represents a much larger body of 

work carried out in ETL over a period of a decade or more, and is preceded by a number of 

groundbreaking theoretical studies describing the interaction of electromagnetic waves and the 

sea surface, and succeeded by a number of investigations that extended this and related 

technologies to include wider-region coverage offered by satellite and skywave (over-the horizon 

systems that employ the scatter of electromagnetic waves from the ionosphere) systems. The 

system described in this paper was eventually commercialized and is now used worldwide to 

address a variety of current mapping needs. 

Abstract

Mobile coastal units can map variable surface currents in real time to 70 km, using ocean wave 

scatter. 

68
Optimum reception in an impulsive interference environment 

Part I: Coherent detection 

Part II: Incoherent reception 

Arthur D. Spaulding 

 OT Institute for Telecommunication Sciences 

David Middleton 

 Contractor 

IEEE Transactions on Communications, COM-25 (9): 910–923 and 924–934, 

September 1977 

Significance

This pair of articles provides a comprehensive review of Don Spaulding’s work in signal 

detection in a non-Gaussian noise environment. The papers make use of a physical-statistical 

interference model to analyze the performance of a large class of digital systems. This model and 

the analysis techniques developed by the authors have found significant use for both system

analysis and the physical design of receiving systems. 

Abstract, Part I

Because communications systems are seldom significantly interfered with by classical white 

Gaussian noise, it is necessary to consider other, appropriate (and tractable) interference models, 

if realistic estimates of system performance are to be obtained for the general spectral-use 

environment. For this purpose, Middleton’s recently developed canonical statistical-physical 

model of “impulsive” interference is applied to real-world communication channels. The 

principal features of this model are first summarized, including the statistical relations required 

for the solution of signal detection problems. [Excellent agreement of these model statistics with 

correspondingly measured statistics is also noted.] 

The model for narrow-band impulsive interference (Class A noise, a subset of the overall model) 

is next specifically applied to an important class of coherent signal detection problems. 

Algorithms for error probabilities in optimum detection are then obtained, along with 

performance bounds, for the same error probabilities. Since it is known that in order to gain 

significant improvement over current receivers, the number of (essentially) independent samples 

of the received interference waveform must be enlarged (i.e., large “processing gains”), the 

performance results here are given parametrically in the number of samples, or equivalently, in 

the time-bandwidth product. Performance of current suboptimum receivers is then obtained and 

compared to the optimum performance. It is shown that very substantial savings in signal power 

and/or spectrum space can usually be achieved by using the indicated optimal algorithms. 

Since physical realization of the completely optimum detection algorithms cannot, in general, be 

economically realized, the somewhat more conservative, corresponding locally optimum Bayes 

69
detection (LOBD) receivers are derived. In general, these LOBD structures require adaptive, 

highly non-linear filters, preceding the conventional correlation detector elements characteristic 

of optimum receivers for Gaussian interference. Performance for these non-linear, optimum 

threshold systems is then determined, specifically in Part I for coherent reception. 

Abstract, Part II 

In Part I, the relevant statistical properties of the recently developed statistical-physical model of 

generalized impulsive interference have been briefly reviewed (for sub Class A noise) and then 

applied specifically to optimum coherent detection. It is shown that by using optimum and 

(locally optimum) detection algorithms (canonically and explicitly derived), substantial savings 

in signal power and/or spectrum space can be achieved for operation in these highly nonGaussian interference environments. This paper (Part II) extends the preceding analysis to cover 

various important cases of incoherent reception. The same general model for narrow-band (Class 

A) impulsive interference and interference examples used in Part I are again employed here. In 

addition to providing both canonical LOBD structures and expressions for performance, this 

permits explicit quantitative comparisons between coherent and incoherent reception for 

common classes of specific digital signal waveforms. 

70
Applications of closed-cycle cryocoolers to small superconducting devices 

James E. Zimmerman and Thomas M. Flynn, editors 

 NBS Electromagnetic Technology Division 

NBS Special Publication 508, 1978 

Significance

This NBS Special Publication is the proceedings of a conference organized by Jim Zimmerman 

and held at NBS on October 3-4, 1977. This conference started what has become the 

International Cryocooler Conference (ICC) that is held every two years. The 13th ICC was held 

at the end of March, 2004. The initial NBS conference reported in this special publication is now 

referred to as the 0th International Cryocooler conference rather than the 1st because of a mixup 

in naming them at a later date. What is known as the 1st was also organized by Jim Zimmerman 

and held at NBS in 1980. The ICC now draws about 250 attendees and over 100 papers at each 

conference. The proceedings are about 1000 pages each and have been published by 

Plenum/Kluwer Press since the 8th ICC. The ICC and its proceedings are the major source of 

published papers related to cryocoolers. 

Abstract 

This document contains the proceedings of a meeting of specialists in small superconducting 

devices and in small cryogenic refrigerators. Industry, Government, and academia were 

represented at the meeting held at the National Bureau of Standards (NBS) on October 3 and 4, 

1977. The purpose of the meeting was to define the refrigerator requirements for small 

superconducting devices and to determine if small cryogenic refrigerators that are produced in 

relatively large quantities can be adapted or developed to replace liquid helium as the cooling 

medium for the superconducting devices. Because the focus was on small superconducting 

devices, the discussion was primarily limited to refrigerators with capacities from zero up to a 

watt or two in the temperature range of 2 to 20 K. The meeting was jointly sponsored by the 

Office of Naval Research (ONR) and NBS. 

71
Picosecond domain waveform measurements 

Norris S. Nahman 

 NBS Electromagnetic Technology Division 

Proceedings of Institute of Electrical and Electronics Engineers, Special Issue on 

Electromagnetic Measurements Science, Invited Paper, 66(5): 441–454, April 1978 

Significance

This seminal paper recognized and emphasized the importance of bringing together electrical and 

optical picosecond domain pulse measurement technologies into a unified technology. The 

technologies described in the paper ranged from DC to terahertz electrical techniques, including 

superconductive devices and Debye polar molecular pulse-forming filters, optical pulse

generation and sampling of electrical pulse measurements, electrical and optical auto- and crosscorrelation methods, and computer controlled measurement and signal processing of picosecond 

domain electrical and optical pulse waveforms. The paper in its entirety was translated and 

published in Japanese by McGraw-Hill in Nikkei Electronics with the banner admonition, “Every 

electronics engineer in Japan should read this paper” (Nikkei Electronics, April 1979, Tokyo, 

Japan). 

Abstract 

A review of the state-of-the-art of picosecond time-domain measurements is presented which 

draws together techniques from the electrical and optical regions of the electromagnetic 

spectrum. Measurement methods are listed in categories, which exhibit the commonality 

between electrical and optical methods. State-of-the-art values for temporal resolution are 

presented with reference citations to specific methods and related technical topics. 

72
Radiation-pressure cooling of bound resonant absorbers 

David J. Wineland, Robert E. Drullinger, and Fred L. Walls 

 NBS Time and Frequency Division 

Physical Review Letters, 40: 1639-1642, 1978 

Significance

This paper described the first experimental observation of laser-cooling particles (in this case, 

ions) to low temperatures. It opened up a new field of using light to manipulate the translational 

states of atomic particles. Today, laser-cooling is used in atomic clocks and frequency standards. 

It is also one of the first steps in cooling atomic gases to quantum degeneracy where BoseEinstein Condensation has been observed. This work underpins the current U.S. standard for 

time and frequency (NIST-F1 laser-cooled atomic fountain clock), led to two Nobel prizes, and 

opened up a large vigorous global research effort spanning such topics as quantum computing, 

atom lasers, and new states of matter.

NIST Fellow Dave Wineland was one of the originators in 1975 of the concepts of using lasers 

to cool atoms or ions to very near absolute zero. Wineland joined NBS in 1975 and his group 

soon turned those concepts into reality, using laser to cool magnesium ions to about 40 Kelvin 

(40 degrees above absolute zero), the first demonstration of laser cooling of any species 

(simultaneously and independently of a demonstration by Peter Toschek and Hans Dehmelt). 

Wineland’s group’s work led directly to work by several other groups throughout the world on 

laser cooling and trapping of neutral atoms. Wineland’s group and other NIST researchers have 

been world leaders in this field for more than 20 years, as demonstrated in part by the 1997 

Nobel Physics Prize to NIST’s Bill Phillips (along with Steve Chu and Claude Cohen-Tannoudji) 

for development of neutral atom laser cooling, and the 2001 Nobel Physics Prize to NIST’s Eric 

Cornell (along with Carl Weiman and Wolfgang Ketterle) for using laser cooling to create the 

Bose-Einstein Condensate, a new form of ultra-cold matter. Wineland’s work has led NIST 

researchers to current cutting-edge research on quantum computing, atomic clocks, atom lasers, 

fundamental research on the properties of quantum mechanics, and a host of other advances. This 

paper is one of the top 50 papers in physics for the 20th century. 

Abstract 

We report the first observation of radiation pressure cooling on a system of resonant absorbers 

which are elastically bound to a laboratory fixed apparatus. Mg II ions confined in a Penning 

electromagnetic trap are cooled to <40 K by irradiating them with the 8-μW output of a 

frequency doubled, single-mode dye laser tuned to the low-frequency side of the Doppler profile 

on the 2

S1/2 ↔ 2P3/2 (MJ = +1/2 ↔ MJ = +3/2 or MJ = –1/2 ↔ MJ = –3/2) transitions. Cooling to 

approximately 10-3 K should be possible. 

73
A hybrid of Erlang B and C formulas and its applications 

Martin Nesenbergs 

 NTIA Institute for Telecommunication Sciences 

IEEE Transactions on Communications, COM-27 (1): 59–68, January 1979 

Significance

This paper integrates and extends the classical Erlang B (“blocked calls lost”) and Erlang C 

(“blocked calls delayed”) formulas for calculating grade of service in switched 

telecommunication networks by introducing a new parameter (2) that describes customer 

behavior when a customer request cannot immediately be served due to network congestion. The 

paper is important because it defines a practical means of dimensioning and operating networks 

that support different types of traffic (e.g., telephone calls and store-and-forward data) and must 

meet grade-of-service objectives under conditions not addressed by the classical formulas (e.g., 

variable customer responses to blocked service requests, alternate routing, repeated call attempts, 

traffic control). These real-world conditions will need to be addressed in emerging multi-service 

networks supporting assured quality levels (e.g., packet-based NGNs). 

Abstract 

This paper attempts to broaden the usefulness of existing Erlang grade of service formulas, 

especially when faced with the evolving extensive changes in telephone networks. The old 

Markov traffic arrival and Markov call duration (or service) models are combined with what may 

be called more realistic user behavior and network scenarios. For the specified service system

models, a generalized merger of ideal loss and ideal delay steady-state representations is 

developed. It is shown that a particular weighted inverse combination of Erlang B and C

formulas, herein called the hybrid, is useful for grade of service estimates under several 

conditions. In addition to the usual offered load and the number of servers, the hybrid involves a 

relative Erlang B versus C weighting parameter θ. This parameter is non-negative and depends 

on system applications, as illustrated in a number of examples given. When less than or equal to 

unity, such as for the popular Poisson model, θ has a simple meaning. It is then the conditional 

probability that a typical customer elects to wait, or a service request is entered into a queue, 

given that all servers are busy. 

74
Mesoanalysis of the Big Thompson storm 

Fernando Caracena, Robert A. Maddox, and Charles F. Chappell 

 NOAA Atmospheric Physics and Chemistry Laboratory 

L. Ray Hoxit 

 Federal Aviation Administration

Monthly Weather Review, 107, 1–17, 1979 

Significance

The study of the Big Thompson flash flood presented in this paper became a landmark because it 

awakened the meteorological community to the importance of forecasting flash floods. It 

resulted in other new initiatives related to flash floods that have since matured into programs. 

Several components of this future work were accomplished by members of the 

Mesometeorological Group, who were awarded a NOAA Unit Citation for their initial work, 

which paved the way for many other publications on this subject. 

Abstract

Mesoscale analyses and descriptions of meteorological conditions that produced the devastating 

flash flood in the Big Thompson Canyon on 31 July 1976 are presented. The storm developed 

when strong low-level easterly winds to the rear of a polar front pushed a moist, conditionally 

unstable air mass upslope into the Front Range of the Rocky Mountains. The main thrust of the 

moisture flux focused initially into the Big Thompson area. Orographic uplift released the 

convective instability, and light south-southeasterly winds at steering levels allowed the storm

complex to remain nearly stationary over the foothills. Heavy rains fell within the storm along a 

narrow corridor only 5 km wide oriented north-northeast by south-southwest. Minimal 

entrainment of relatively moist air at middle and upper levels, very low cloud bases and a 

slightly tilted updraft structure contributed to a high precipitation efficiency. A deep, warm layer 

of convective cloud fostered precipitation growth through warm cloud processes. The greatest 

concentrations of precipitation size particles remained at low elevations and as result of poor 

vertical beam resolution returned anomalously weak radar echoes to a WSR-57 located 110 n mi

away. 

75
“Thru-reflect-line”: An improved technique for calibrating the dual six-port 

automatic network analyzer 

Glenn F. Engen and Cletus A. Hoer 

 NBS Electromagnetic Technology Division 

IEEE Transactions on Microwave Theory and Techniques, MTT-27(12): 987–993, 

December 1979 

Significance

The work in this paper formalizes the use of transmission lines as impedance standards. It was a 

major breakthrough in that it led to a calibration scheme which did not require the use of a 

known short or other calibration “circuits.” This laid the foundation for the use of six-port 

systems developed at NIST over the past 20 years. These systems cover the frequency range 

from 10 MHz to 100 GHz and are still used for NIST calibration services of thermistor detectors 

and n-port devices. This work has been extensively referenced in the literature as the methods 

developed in that paper remain the most accurate for calibration vector network analyzers. The 

myriad of calibration schemes are ultimately compared to the TRL method developed by Hoer 

and Engen. 

Abstract 

In an earlier paper, the use of a “thru-short-delay” (TSD) technique for calibrating the dual sixport automatic network analyzer was described. Another scheme required only a length of 

precision transmission line and a “calibration circuit.” The better features of these two somewhat 

different approaches have now been combined and the requirement for either a known short, or a 

“calibration circuit” eliminated. This paper will develop the theory for this new procedure. 

76
Papers from the 1980s 

Analytical and numerical techniques for analyzing an electrically short dipole 

with a nonlinear load 

Motohisa Kanda, 1980 81 

Ground wave attenuation function for a spherical earth with arbitrary surface impedance 

 David A. Hill and James R. Wait, 1980 82 

Interactive FORTRAN IV computer programs for the thermodynamic and transport 

properties of selected cryogens (fluids pack) 

Robert D. McCarty, 1980 83 

Fracture and strength properties of selected austenitic stainless steels at cryogenic temperatures 

 David T. Read and Richard P. Reed, 1981 84 

Plane-wave scattering-matrix theory of antennas and antenna-antenna interactions 

David M. Kerns, June 1981 85 

Prediction of transport properties, 1. Viscosity of fluids and mixtures 

 James F. Ely and Howard J.M. Hanley, 1981 86 

Selected properties of hydrogen (engineering design data) 

 Robert D. McCarty, Jesse Hord, and Hans M. Roder, 1981 87 

A guide to the use of the ITS irregular terrain model in the area prediction mode 

 George A. Hufford, Anita G. Longley, and William A. Kissick, 1982 88 

An attenuation function for multiple knife-edge diffraction 

Lewis E. Vogler, 1982 89 

Critical current measurements: A compendium of experimental results 

 Loren F. Goodrich and Fred R. Fickett, 1982 90 

Optical fiber characterization, Volumes 1 and 2 

 George E. Chamberlain, Bruce L. Danielson, Gordon W. Day, Douglas L. Franzen, 91 

 Robert L. Gallawa, Ernest M. Kim, and Matt Young, 1982 

Design and error analysis for the WR10 thermal noise standard 

William C. Daywitt, December 1983 92 

Direct frequency measurement of the I2-stabilized He–Ne 473-THz (633 nm) laser 

 Donald A. Jennings, Clifford R. Pollock, F. Russell Petersen, Robert E. Drullinger, 

 Kenneth M. Evenson, Joseph S. Wells, John L. Hall, and Howard P. Layer, 1983 93 

77
Large-scale meteorological conditions associated with midlatitude, mesoscale convective 

complexes 

Robert A. Maddox, 1983 94 

Liquefied natural gas densities: Summary of research program at the National Bureau of 

Standards 

 William M. Haynes, Robert D. McCarty, and Michael J. Hiza, 1983 95 

Materials at low temperatures 

 Richard P. Reed and Alan F. Clark, 1983 97 

The Colorado wind-profiling network 

 Richard G. Strauch, David A. Merritt, Kenneth P. Moran, Kenneth B. Earnshaw, 

 and Douglas van de Kamp, 1984 98 

A practical Josephson voltage standard at 1 V 

 Clark A. Hamilton, Richard L. Kautz, and Frances L. Lloyd, 1985 99 

Electron-tunneling experiments using Nb-Sn “break” junctions 

 John Moreland and Jack W. Ekin, 1985 100 

A comparison of three types of pulse tube refrigerators: New methods for reaching 60 K 

 Ray Radebaugh, James Zimmerman, David R. Smith, and Beverly Louie, 1986 101 

On the depletion of Antarctic ozone 

 Susan Solomon, Rolando R. Garcia, F. Sherwood Rowland, 

and Donald J. Wuebbles, 1986 102 

Reducing the risk of refinery explosions: 

1. Examination of a pressure vessel that ruptured at the Chicago refinery of the Union 

Oil Company on July 23, 1984 

 Harry I. McHenry, T. Robert Shives, David T. Read, J. David McColskey, 104 

 Charles H. Brady, and Patrick T. Purtscher, 1986 

2. Observations of hydrogen damage in a failed pressure vessel 

 Harry I. McHenry, Patrick T. Purtscher, and T. Robert Shives, 1987 104 

3. Failure analysis of an amine-absorber pressure vessel 

 Harry I. McHenry, David T. Read, and T. Robert Shives, 1987 104 

Models and observations of the impact of natural hydrocarbons on rural ozone 

 Michael Trainer, Eric J. Williams, David D. Parrish, Martin P. Buhr, Eugene J. Allwine, 

 Halvor H. Westberg, Fred C. Fehsenfeld, and Shaw C. Liu, 1987 106 

78
Second viscosity and thermal conductivity virial coefficients of gases: 

Extension to low reduced temperature 

 James C. Rainwater and Daniel G. Friend, 1987 107 

Tunneling spectroscopy of a La-Sr-Cu-O break junction: Evidence for strong coupling 

superconductivity 

 John M. Moreland, Alan F. Clark, Loren F. Goodrich, Harry C. Ku, 

and R.N. Shelton, 1987 108 

Error analysis techniques for planar near-field measurements

Allen C. Newell, 1988 109 

Josephson-junction model of critical current in granular Y1Ba2Cu3O7–δ superconductors 

 Robert L. Peterson and Jack W. Ekin, 1988 110 

Handbook of basic tables for chemical analysis 

 Thomas J. Bruno and Paris D.N. Svoronos, 1989 111 

MPM—An atmospheric millimeter-wave propagation model 

Hans J. Liebe, 1989 112 

Performance standards for packet-switched services 

Neal B. Seitz, 1989 113 

Stainless steel weld metal: Prediction of ferrite content 

 Chris N. McCowan, Thomas A. Siewert, and D.L. Olson, 1989 114 

The accuracy of RASS temperature measurements 

 Peter T. May, Kenneth P. Moran, and Richard G. Strauch, 1989 115 

Automated Computer Time Service: 

 1. The NIST Automated Computer Time Service 

 Judah Levine, Marc Weiss, Dickie D. Davis, David W. Allan, and D.B. Sullivan, 1989 116 

2. Time synchronization using the Internet 

Judah Levine, 1998 116 

79
80
Analytical and numerical techniques for analyzing an electrically short dipole 

with a nonlinear load 

Motohisa Kanda 

 NBS Electromagnetic Fields Division 

IEEE Transactions on Antennas and Propagation, AP-28(1): 71–78, January 1980 

Significance

This paper develops the principles for dipole probes used to measure electric fields. This basic 

design led to the successful development of a wide variety of NIST field probes as well as being 

adopted by industry as the basis for commercial probes. These short dipole probes form the 

backbone for many antenna calibrations, electromagnetic compatibility test site qualification, 

radiation hazard monitoring, and bioelectromagnetic effects characterization. Subsequent papers 

on field probe development and application often begin with a reference to this fundamental 

paper. 

Abstract 

An electrically short dipole with a nonlinear dipole load is analyzed theoretically using both 

analytical and numerical techniques. The analytical solution is given in terms of the Anger 

function of imaginary order and imaginary argument and is derived from the nonlinear 

differential equation for the Thévenin’s equivalent circuit of a dipole with a diode. The 

numerical technique is to solve the nodal equation using a time-stepping finite difference 

equation method. The nonlinear resistance of the diode is treated using the Newton–Raphson 

iteration technique. A comparison between the analytical and numerical solutions is given. 

81
Ground wave attenuation function for a spherical earth with arbitrary 

surface impedance 

David A. Hill 

 NTIA Institute for Telecommunication Sciences 

James R. Wait 

 NOAA Environmental Research Laboratory 

Radio Science, 15(3): 637–643, May–June 1980 

Significance

For layered earth models with arbitrary conductivity, permittivity, and permeability, the surface 

impedance can take on a large range of complex values. This paper was the first to treat groundwave propagation over a spherical earth for arbitrary surface impedance and path length. This 

required the use of several methods of calculation (residue series, power series, and small 

curvature approximation) in order to write a completely general computer code. Various 

propagation effects (such as the trapped surface wave for an inductive surface impedance) are 

illustrated numerically for a vertical electric dipole source for frequencies from 1 to 30 MHz. 

The computer code was requested by many users outside the Boulder Laboratories for about 10 

years after publication of the paper. 

Abstract 

Previous methods developed for computation of the attenuation function for a homogeneous 

spherical earth are generalized for an arbitrary surface impedance. The power series and smallcurvature formula developed for short distances can be used for such surfaces without 

modification. Care must be taken, however, to include properly the trapped surface wave that 

may arise in the formulation. In general, it is found that the inductive type of boundary enhances 

the total field but, if the resistive part is small, rather strong interference takes place between the 

trapped surface wave and the usual ground wave. These effects are illustrated for a surface-based 

vertical electric dipole for frequencies from 1 to 30 MHz. 

82
Interactive FORTRAN IV computer programs for the thermodynamic and 

transport properties of selected cryogens (fluids pack) 

Robert D. McCarty 

 NBS Thermophysical Properties Division 

NBS Technical Note 1025, 1980 

Significance

The dissemination of standardized thermophysical property information from NBS evolved from

reams of tables and hand-drawn curves to computer programs—on tapes, personal computers, or 

through the World Wide Web. This Tech Note from 1980 describes a very early version of a 

computer program used to calculate the properties of several fluids at arbitrary values of 

temperature and pressure. The work actually provides a listing of the source code used in the 

computer program and provides source references and even uncertainty estimates for the 

calculated values. This “Fluids Pack” computer program is the forerunner of several 

computerized standard reference databases. The program was adopted as a standard calculational 

tool within NASA, and thus has become part of the space program, an important part of our 

explorations from the moon to the stars. 

Abstract

The thermodynamic and transport properties of selected cryogens have been programmed into a 

series of computer routines. Input variables are any two of P, ρ or T in the single phase regions 

and either P or T for the saturated liquid or vapor state. The output is pressure, density, 

temperature, entropy, enthalpy for all of the fluids and in most cases specific heat capacity and 

speed of sound. Viscosity and thermal conductivity are also given for most of the fluids. The 

programs are designed for access by remote terminal; however, they have been written in a 

modular form to allow the user to select either specific fluids or specific properties for particular 

needs. 

The program includes properties for hydrogen, helium, neon, nitrogen, oxygen, argon, and 

methane. The programs include properties for gaseous and liquid states usually from the triple 

point to some upper limit of pressure and temperature which varies from fluid to fluid. Computer 

listings of the FORTRAN IV codings are presented. 

83
Fracture and strength properties of selected austenitic stainless steels at 

cryogenic temperatures 

David T. Read and Richard P. Reed 

 NBS Fracture and Deformation Division 

Cryogenics, 415-417, July 1981 

Significance

This paper is one of many on mechanical properties of materials at low temperatures that were 

produced by NIST Boulder. This particular paper established the quantitative trade-off between 

strength and toughness for these materials. This relationship was used in the design and selection 

of weld processes. 

Austenitic stainless steels have an excellent combination of mechanical and physical properties 

for load-bearing structures of large superconducting magnets for plasma containment in 

magnetic fusion experiments. To assess their relative suitability, fracture toughness, fatigue crack 

growth, and tensile properties data for five austenitic steels at 295, 76, and 4 K were obtained. 

The steels were AISI 304, 316, 304LN, and 316LN, and an Fe-21Cr-12Ni-5Mn alloy with a 

higher nitrogen content than the other four grades. The two principal findings were the 

systematic variation of yield strength with nitrogen content and a systematic inverse correlation 

between fracture toughness and yield strength. Data from previous studies confirmed the trends 

of the present data. 

Abstract

Nitrogen-strengthened austenitic stainless steels have attracted interest as cryogenic structural 

materials because of their superior strength but data on their toughness at cryogenic temperatures 

are scarce. As cryogenic structures become larger and magnetic fields more intense, materials 

with higher strengths than the widely used alloy AISI 304 are necessary. In fact, nitrogenstrengthened AISI 304LN and 316LN have been selected for, respectively, the magnet cases for 

the Magnetic Fusion Test Facility at Lawrence Livermore Laboratory and a toroidal field coil 

being built for the Large Coil Project. Clearly, development of a data base on the structural 

properties of nitrogen-strengthened austenitic stainless steels is needed to support materials 

selection and design for the large cryogenic magnet structures of the near future. 

84
Plane-wave scattering-matrix theory of antennas and antenna-antenna 

interactions 

David M. Kerns 

 NBS Electromagnetic Fields Division 

NBS Monograph 162, June 1981 

Significance

This monograph is David Kerns’ final compilation on the subject of near-field antenna 

measurements and was published in 1981 shortly before he retired. It remains the best and most 

exhaustive treatment of planar near-field scanning theory. Under the leadership of Kerns and 

other pioneers at NBS, near-field techniques have become the preferred methods for 

characterizing the radiating properties of microwave antennas. In addition to the well-known 

NIST antenna group, several universities maintain active near-field measurement research 

programs. Half a dozen companies market near-field scanning equipment and well over 200 

laboratories, worldwide, routinely perform near-field measurements. The IEEE Antennas and 

Propagation Society has published a special issue (IEEE Transactions on Antennas and 

Propagation, June 1988) and regularly features sessions on near-field techniques at its 

conferences.

Abstract 

This monograph is distinguished by the use of plane-wave spectra for the representation of fields 

in space and by the consideration of antenna-antenna (and antenna-scatterer) interactions at 

arbitrary separation distances. The plane-wave representation is eminently suitable for this 

purpose as well as for the expression of conventional asymptotic quantities of antenna theory, 

such as power gain, effective area, and polarization. The primary objective of the monograph is 

to facilitate the critical acceptance and proper application of antenna scattering-matrix (PWSM) 

theory of antennas and antenna-antenna interactions. A secondary objective is to present some

recent and some new theoretical results based on this theory. The three chapters of this 

monograph provide (a) an introduction to the basic theory and practice of microwave network 

analysis (which form an inescapable part of microwave antenna measurement expertise); (b) a 

thorough formulation of the PWSM theory of antennas and antenna-antenna interactions, 

including analytical techniques for derived measurement methods; and (c) recent and new 

theoretical results and analytical examples. Topics in (c) include: a convenient and attractive 

reformulation of the PWSM theory; some theory of minimum scattering antennas; theory of 

classes of completely solvable antenna-antenna interaction problems; and convergent, asymptotic 

expansions of transmission- and reflection-integrals in reciprocal power of r0, where r0 is the 

magnitude of the relative displacement vector r0 and the direction of r0 is a parameter.

85
Prediction of transport properties, 1. Viscosity of fluids and mixtures 

James F. Ely and Howard J.M. Hanley 

 NBS Thermophysical Properties Division 

Industrial and Engineering Chemistry Fundamentals, 20: 323–332, 1981 

Significance

The theoretical model described in this paper forms the basis for the most accurate and broad 

ranging methods used to describe and predict the viscosity surfaces for a variety of pure fluids 

and mixtures. The work presents an extended corresponding-states principle that allows a 

calculation of viscosity even when very little information on the fluid is available. The model has 

been extended since this early version, but is still being used in the NIST standard reference 

databases for such diverse systems as natural gases, refrigeration fluids, and reservoir fluids. 

Abstract

A model for the prediction of the viscosity of nonpolar fluid mixtures over the entire range of 

PVT states is presented. The model is an extension of an earlier version (Hanley, 1976) to 

molecular weights which roughly correspond to that of C20. The proposed model is based on an 

extended corresponding states principle and requires only critical constants and Pitzer’s acentric 

factor for each component as input. Extensive comparisons with experimental data for pure 

fluids and binary mixtures are presented. The average deviation between experiment and 

prediction is 8 % for pure species and 7 % for mixtures. 

86
Selected properties of hydrogen (engineering design data) 

Robert D. McCarty, Jesse Hord, and Hans M. Roder 

 NBS Thermophysical Properties Division 

NBS Monograph 168, 1981 

Significance

A 20-year effort at the Boulder Laboratories on the properties of hydrogen culminated in the 

publication of this important synthesis of information. The monograph is still in demand today, 

although copies are rare and some information is outdated: the work will soon be available on a 

NIST web site. In addition to thermodynamic property tables and charts for parahydrogen and 

normal hydrogen (two of the important forms), there is some information on combustion 

properties, toxicity, radiative properties, etc. The scope of the work and the care that went into its 

preparation make it a key source of data even for today’s efforts on the “hydrogen economy.” 

Abstract 

The National Bureau of Standards has been engaged in the compilation, review, analytical and 

experimental derivation, and publication of hydrogen properties for over 20 years. The properties 

data presented herein are compiled largely from those accumulated data; of course, pertinent data 

and work of other researchers in the field are also included. 

The general interests of scientists and engineers engaged in energy systems studies were given 

top priority in choosing the properties material presented in this book. Hydrogen systems cut 

across many energy related fields, e.g., nuclear fusion, magneto-hydrodynamics, electrolysis and 

thermochemical decomposition of water, coal and shale derivate fuels, solar and wind power, 

ocean energy, geothermal processes, etc. It is generally conceded that hydrogen could be used to 

satisfy virtually all fuel requirements that are currently being met with natural gas and oil. To 

satisfy the demand for properties data over this broad spectrum of interests, we have attempted to 

provide comprehensive coverage of physical properties over a wide range of pressures and 

temperatures. 

Thermophysical properties of liquid, liquid-vapor, vaporous, and gaseous hydrogen are presented 

in Chapter 1 and the solid-liquid, solid-vapor, and solid phase properties are compiled in Chapter 

2. Ortho-para modifications of the hydrogen molecule and attendant property variations are 

considered in both chapters. Combustion and safety data, pertinent to hazard analysis of

hydrogen systems, is collected in Chapter 3. Important miscellaneous properties are compiled in 

Chapter 4, data figures are compiled in Chapter 5, data tables are collected in Chapter 6, and 

Chapter 7 summarizes symbols, units, and conversion factors used throughout the book. 

87
A guide to the use of the ITS irregular terrain model in the area prediction 

mode 

George A. Hufford, Anita G. Longley, and William A. Kissick 

 NTIA Institute for Telecommunication Sciences 

NTIA Report 82-100, April 1982 

Significance

The “Guide” describes the basis of the ITS Irregular Terrain Model (ITM or Longley–Rice 

Model), its implementation, and some advantages and limitations of its use. In addition, sample 

problems using the model in the area (site-general) prediction mode are included to demonstrate 

applications of the model. This classic work contains a description and implementation (version 

1.2.1) of the model as it developed and matured in the years subsequent to the publication of the 

“Computer Method” (Longley and Rice 1968, this volume). In particular, the algorithm and its 

modular implementation found here represent dramatic improvements that endure to the present. 

In addition to providing definitive descriptions of the use of the model and its limitations, the 

sample problems contained here established methods of application which still guide present 

users. More than 20 years after this report was published, the ITS publications office receives 

requests for this volume almost every week. 

Abstract 

The ITS model of radio propagation for frequencies between 20 MHz and 20 GHz (the Longley–

Rice model) is a general purpose model that can be applied to a large variety of engineering 

problems. The model, which is based on electromagnetic theory and on statistical analyses of 

both terrain features and radio measurements, predicts the median attenuation of a radio signal as 

a function of distance and the variability of the signal in time and in space.

The model is described in the form used to make “area predictions” for such applications as 

preliminary estimates for system design, military tactical situations and surveillance, and landmobile systems. This guide describes the basis of the model, its implementation, and some

advantages and limitations of its use. Sample problems are included to demonstrate applications 

of the model.

88
An attenuation function for multiple knife-edge diffraction 

Lewis E. Vogler 

 NTIA Institute for Telecommunication Sciences 

Radio Science, 17(6): 1541–1546, November–December 1982 

Significance

For analytical and computational tractability reasons, terrain and other obstacles on the path in 

radio propagation problems are often approximated as a series of perfectly absorbing knifeedges. This publication presented a nearly exact expression for an arbitrary sequence of multiple 

(more than two) knife-edges. This was a great improvement on approximate solutions that relied 

on linear combinations of the single knife-edge function. In addition, it provided a series 

approximation to the exact expression that could be implemented in a numerically tractable 

fashion. Finally, the results for several sample calculations of interest were presented, along with 

derivations of certain closed form limiting results. Elegant and nonintuitive, this technique is the 

most logical way to deal with the knife-edge problem, and is considered the “gold standard” in 

this area. 

Abstract 

A recently derived attenuation function for multiple knife-edge diffraction is described, and 

some example calculations are presented. The function, in the form of a multiple integral, is 

transformed into a series representation which is amenable to computer implementation. A 

program has been written to compute the attenuation over propagation paths containing up to a 

maximum of ten knife-edges. Attenuation curves for three example paths are presented showing 

the effects of multiple knife-edges on the received signal. A means of estimating the statistical 

distribution of attenuation for a given path from statistical knowledge of the atmospheric surface 

refractivity is suggested.

89
Critical current measurements: A compendium of experimental results 

Loren F. Goodrich and Fred R. Fickett 

 NBS Electromagnetic Technology Division 

Cryogenics, 22(5): 225–241, May 1982 

Significance

The key measurement for practical, large-scale superconductor applications is that of “critical 

current,” the current-carrying capacity of a superconductor. Critical current is difficult to 

measure accurately, as demonstrated in many interlaboratory comparisons in which it is not 

unusual to find measurement discrepancies of up to 30 %. This landmark paper—published in 

Cryogenics, the leading journal in the field—reviewed and advanced NIST metrology for critical 

current. It includes an evaluation of the effect of approximately 30 experimental parameters on 

the critical-current determination. Everything from sample geometry and holder material to 

suggested uncertainties for 10 variables is described. 

The paper was the prime reference in the first superconductor measurement standard in the 

world, published in 1982 by the American Society for Testing and Materials (ASTM). It also 

formed the basis for the first standard published by the International Electrotechnical 

Commission (IEC) in 1998. This compendium paper was also used as a guide in the late 1980s 

when high-temperature superconductors were discovered, and when the excitement of this 

discovery brought many new researchers into the field. Even with the new materials and 

advances that have taken place in superconductor research, the paper has stood the test of time 

and remains relevant to even today’s best superconductors. 

Abstract 

The results of a program to evaluate the measurement of the critical current of relatively small 

(<600 Å) practical superconductors are presented. Experimental data showing the effect of 

various parameters on the measurement are given. Specific areas covered are: experimental 

design and sample mounting; electric field and resistivity criteria; temporal and spatial variations 

in the field and current; and temperature and strain effects. The goal of the presentation is to 

describe the critical current measurement process and its pitfalls in sufficient detail to serve as a 

guide for those relatively new to the field of practical superconductors. 

90
Optical fiber characterization, Volumes 1 and 2 

George E. Chamberlain, Bruce L. Danielson, Gordon W. Day, Douglas L. Franzen, Robert L. 

Gallawa, Ernest M. Kim, and Matt Young 

 NBS Electromagnetic Technology Division 

NBS Special Publication 637, 1982 

Significance

These volumes are a collection of NBS Technical Notes that individually discuss specific areas 

of optical fiber characterization. The Tech Notes appeared during the commercial infancy of 

optical telecommunications fiber. During that period, commercially viable fibers were of the 

multimode type; that is, they supported the transmission along the fiber of a number of 

electromagnetic modes having different combinations of electric field and magnetic field 

configurations. While single mode fibers could be fabricated, the technology to exploit them was 

not readily available. Thus, this work is primarily concerned with the characterization of 

multimode fiber. In the early 1980s, single mode fiber became technically accessible, and today s 

long distance and metropolitan telecommunication networks consist solely of single mode fiber. 

However, multimode fiber is still used in high speed local area networks (LANs). 

Fiber optic technology is measurement intensive, and multimode fibers present significant 

characterization problems. In the early period of optical fiber development, there were no 

standard measurement procedures. In a large U.S. standards effort started by the Electronic 

Industries Association, NBS acted as a neutral party to evaluate procedures proposed by 

industry. In most cases, the measurement techniques described in these volumes were, or 

became, industry standards. The efforts described here also provided the impetus for future 

NBS/NIST programs in optical fiber metrology. Fiber metrology is now a major component of 

the Optoelectronics Division. These volumes were identified as one of the 100 most significant 

NBS/NIST papers at the centennial celebration. 

Abstract, Volume 1 

Optical fiber waveguide measurements are described. Systems to determine the backscatter, 

bandwidth, and index profile are covered in detail. Measurement comparisons between 

laboratories are given for fiber attenuation, bandwidth, numerical aperture, and core diameter. 

Abstract, Volume 2 

This is the second volume of a series intended to describe optical fiber measurement systems 

developed at the National Bureau of Standards. The topics covered in this volume are 

attenuation, bandwidth (frequency domain), and far-field near-field radiation patterns. Each 

chapter includes a tutorial section and a detailed description of the apparatus. The volume

concludes with a glossary of optical communications terms. 

91
Design and error analysis for the WR10 thermal noise standard 

William C. Daywitt 

 NBS Electromagnetic Fields Division 

NBS Technical Note 1071, December 1983 

Significance

This paper introduces the cryogenic primary noise standard, a significant improvement in the 

calibration of noise sources because of its high accuracy and immunity from deterioration that is 

common in oven-based noise standards. The cryogenic noise standard described in this Technical 

Note is still in use today at NIST. As well, many modern commercially available primary noise 

standards are based on the NBS design presented here. 

Abstract 

This note describes the design and error analysis of a WR10 thermal noise power standard. The 

standard is designed to operate at the boiling point of liquid nitrogen with a noise temperature 

accurate to ±1 K. 

92
Direct frequency measurement of the I2-stabilized He-Ne 473-THz (633-nm) 

laser 

Donald A. Jennings, Clifford R. Pollock, F. Russell Petersen, Robert E. Drullinger, Kenneth M. 

Evenson, and Joseph S. Wells 

 NBS Time and Frequency Division 

John L. Hall 

 NBS Quantum Physics Division 

Howard P. Layer 

 NBS Length and Mass Measurement and Standards Division 

Optics Letters 8: 136–138, March 1, 1983 

Significance

This paper was a crucial part of research to improve the measurement of the speed of light, 

which then led to international redefinition of the meter. The original definition of the meter was 

based on an artifact, a precision “ruler” maintained at the International Bureau of Weights and 

Measures in France. In 1960, the meter was redefined based on the wavelength of an optical 

transition in the atom krypton. But rapid improvements in laser technology after its 1961 

introduction led to new high precision measurements of the speed of light, the meter, and 

frequency, which are all interrelated. This paper reported exquisitely accurate measurements of a 

wide range of frequencies, all directly interlinked, which reduced the uncertainty in the speed of

light by a factor of 100. With this improvement, it became clear that the meter could be much 

more accurately defined by basing it on the speed of light, and in 1983 the international 

agreement became: “The meter is the length of the path traveled by light in vacuum during a 

time interval of 1/299 792 458 of a second,” with the speed of light taken as a defined 

fundamental constant. Note that this redefinition makes the meter dependent on the measurement 

of time (the second), which is by far the most accurately realized of the seven fundamental units. 

Abstract 

The absolute frequency of the 473-THz He–Ne laser (633 nm), stabilized on the g or i hyperfine 

component of the 127I2 11–5 R(127) transition, was measured by comparing its frequency with a 

known frequency synthesized by summing the radiation from three lasers in a He–Ne plasma. 

The three lasers were (1) the 88-THz CH4-stabilized He–Ne laser (3.39 μm), (2) a 125-THz 

color-center laser (2.39 μm) with its frequency referenced to the RII(26) 13C18O21aser, and (3) the 

260-THz He–Ne laser (1.15 μm) referenced to an I2-stabilized dye laser at 520 THz (576 nm). 

The measured frequencies are 473 612 340.492 and 473 612 214.789 MHz for the g and i

hyperfine components, respectively, with a total uncertainty of 1.6 parts in 1010. The frequency 

of the i component adjusted to the operating conditions recommended by the Bureau 

International des Poids et Mesures is 473 612 214.830 ± 0.074 MHz. 

93
Large-scale meteorological conditions associated with midlatitude, mesoscale 

convective complexes

Robert A. Maddox 

 NOAA Weather Research Program 

Monthly Weather Review, 111: 1475–1493, 1983 

Significance

After establishing quantitative criteria that essentially defined Mesoscale Convective Complexes 

(MCCs), here Maddox describes the large-scale settings in which MCCs form. His work inspired 

a large body of further research, including yearly summaries of MCC occurrences in the United 

States, a (successful) search for MCCs on other continents, examinations of the hydrologic 

significance of the severe weather produced in MCCs, and modeling studies intent on setting out 

the physical mechanisms driving these large mesoscale circulations. The concept of MCCs helps 

to explain several other phenomena, e.g., the nocturnal maximum of warm season rainfall 

observed over much of the central and northern US. It has also initiated continued debate over 

whether MCCs are distinct meteorological phenomena with an inherent scale, or if they are 

simply one of many on a continuum of scales between convective cells and short waves. Warmseason precipitation forecasting has been strongly influenced by the understanding of MCCs, 

enabling forecasters to put the large anvil features seen on satellite imagery in context.

Abstract

Objective analyses of composited meteorological conditions attending ten Mesoscale Convective 

Complexes (MCC) reveal a number of distinctive characteristics and important interactions with 

the large-scale environment. The systems appear to be linked to eastward progression of a weak, 

middle-tropospheric, short-wave trough. Initial thunderstorms develop within a region of 

mesoscale convergence and lifting that is apparently forced primarily by low-level warm

advection. The MCC system acquires mesoscale organization while it moves eastward ahead of 

the short-wave trough. Diabatic heating eventually produces a system that is warm core in the 

middle troposphere and cold core in upper levels. The mature MCC exhibits many similarities to 

tropical convective systems, although it occurs within a considerably different large-scale 

setting. Inflow within the lower half of the troposphere feeds convection within a region 

characterized by significant net upward mass flux and widespread precipitation. Thickness 

increases within this region produce anomalously high heights in the upper-troposphere above 

the MCC and intense outflow develops in the region where the height gradient has increased. 

Decay typically occurs as the system moves east of the region of conditionally unstable air and 

low-level warm advection. However, as the system decays, atmospheric response to residual 

temperature perturbations results in intensification of the precursor short-wave trough within the 

upper half of the troposphere.

94
Liquefied natural gas densities: Summary of research program at the 

National Bureau of Standards 

William M. Haynes, Robert D. McCarty, and Michael J. Hiza

 NBS Chemical Engineering Science Division 

NBS Monograph 172, 1983 

Significance

The program in the Boulder Laboratories on the properties of liquefied natural gas (LNG) 

provided the core metrology to allow custody transfer—commerce—in this key commodity. The 

properties of LNG vary, by composition or source, temperature, and pressure, and transport of 

this fuel often involves mixing, cooling, warming, pressurizing and venting. It is important to 

know the fluid properties at each stage of the process. Monograph 172 summarizes the 

measurements made in Boulder as well as models for describing LNG fluids—and an important 

sector of our energy economy is based on the information in this monograph. A one percent error 

in density, which was typical of the state of the art for LNG commerce at the inception of this 

project, corresponds to an inequity of a quarter of million dollars in the assessed value of a single 

shipload of LNG. 

Abstract

This report summarizes the results of a project concerning the densities of liquefied natural gas 

(LNG) and its components. This project, initiated in the Properties of Fluids Section of the 

Cryogenics Division of the National Bureau of Standards in July 1972, was carried out under the 

sponsorship of a consortium of 18 energy companies. 

The experimental part of this project has included the following accomplishments: (a) 

development of a magnetic suspension densimeter for absolute density measurements on liquids, 

including liquid mixtures in equilibrium with their vapor, at temperatures from 90 to 300 K; (b) 

orthobaric liquid density measurements on the major components of LNG, which include 

nitrogen (95–120 K), methane (105–160 K), ethane (l00–270 K), propane (100–288.7 K), 

isobutane (115–300 K), and normal butane (135–300 K); (c) orthobaric liquid density 

measurements on approximately 35 binary mixtures of the above components for all 

combinations except nitrogen + butane systems, primarily in the temperature range of 105 to 130 

K; and (d) orthobaric liquid density measurements on 27 multicomponent mixtures (105–120 K), 

including several LNG-like mixtures with up to 8 components. The total uncertainty of a single 

density measurement is approximately 0.1 percent at low temperatures and decreases to 

approximately 0.06 percent at room temperature. The estimated standard deviation of a single 

density measurement is less than 0.02 percent. 

The density data have been used to optimize, test, and compare several mathematical models as 

to their suitability for the calculation of LNG densities for custody transfer. Models selected for 

95
optimization and testing included an extended corresponding states method, a hard sphere model, 

a cell model, and an empirical model due to Klosek and McKinley. The ultimate goal of this 

project was to produce one or more mathematical models that could be used to predict the 

density of any LNG mixture to within an uncertainty of 0.1 percent from an input of pressure, 

temperature, and composition. After revisions based on the new experimental data from this 

project, each of the models investigated here satisfy this goal for typical LNG compositions. The 

limitations and ranges of validity of the various models are discussed. Also presented are 

techniques for predicting LNG densities from dielectric constant measurements and from excess 

volume calculations. 

The last section of this report consists of publications that provide a complete and detailed 

account of the results of this project. 

96
Materials at low temperatures 

Richard P. Reed and Alan F. Clark, editors 

 NBS Fracture and Deformation Division 

American Society for Metals, 1983, 590 pp. 

Significance

This book summarizes about 30 years of data and experience developed within the Cryogenics 

Division of NBS. Most of the chapters are on categories of properties such as: elastic properties, 

specific heat, thermal expansion, thermal conductivity, electrical properties, magnetic properties, 

mechanical properties, and fracture mechanics. Other chapters look at particular materials classes 

such as structural alloys, composites, and superconductors. 

The book describes the division’s support of the industries that required low-temperature data 

and materials. Study of the technical roadblocks led to both new materials (cryogenic structural 

alloys with higher strength and higher toughness, better insulators, and improved 

superconductors) and improved procedures and designs (lower loss Dewars, reduction in thermal 

stresses through balancing of material expansion, quantitative design assessment techniques, and 

test procedures that reflect new parameters). 

Abstract (since the book has no abstract, a selection from the Preface is given here) 

.... The thirteen contributors to this book formed the nucleus of the materials group of the 

Cryogenics Division of the National Bureau of Standards (NBS). The Division was formed in 

1952 as part of the expansion of NBS to their new Boulder (Colorado) Laboratories, and our 

group was composed of specialists in physical and mechanical properties of solids at low 

temperatures. We primarily served emerging low-temperature technologies requiring cryogenic 

materials, such as space, LNG storage and transportation, magnetohydrodynamic energy 

conversion, fusion, high-energy physics, and other aspects of applied superconductivity. We

evolved into the largest materials research group in the free world devoted to low-temperature 

research. 

We have now dispersed into several disciplines, but most of our low-temperature research 

capabilities and interests remain. While these are still strong, we thought it appropriate to 

summarize our data and experience in this book. We hope our contributions will establish a firm

basis for the understanding of materials behavior and property measurement to use for design 

and material selection at low temperatures .... 

97
The Colorado wind-profiling network 

Richard G. Strauch, David A. Merritt, Kenneth P. Moran, Kenneth B. Earnshaw, and 

Douglas van de Kamp

 NOAA Wave Propagation Laboratory 

Journal of Atmospheric and Oceanic Technology, 1(1): 37–49, 1984 

Significance 

This paper describes the work that led to the deployment of the NOAA Wind Profiling Network 

that was implemented in 1989 and continues to provide real-time wind data today. The 

techniques developed for the Colorado Wind-Profiling Network formed the basis for the original 

specifications to industry for procurement of the NOAA profilers. The wind profiling method 

described in this paper is still how Doppler wind profilers are operated worldwide. This work 

built on research conducted in the Aeronomy Lab and subsequently transferred to the Forecast 

Systems Lab. The Colorado network comprised VHF radars and the first UHF wind profiler 

radar. This latter was crucial for showing that wind profilers could be operated at higher 

frequencies where frequency authorizations were possible and with smaller antennas where sites 

were more readily available. 

The development of the Doppler wind profiler technology within the Boulder Labs has resulted 

in significant impacts to the nation, and the world, primarily in improved weather forecasts and 

safety of life and property. This technology represents the most significant advancement in 

continuous, all-weather, real-time atmospheric wind measurements in the past 50+ years. NOAA 

and the National Weather Service distribute the data worldwide for use by many other 

meteorological agencies. Data from the NOAA Network have even been shown to improve 

weather forecasts in Europe. In addition, economic, health, and additional safety benefits have 

been realized, including new manufacturing/repair activities that developed in support of the 

wind profiling technology, improved aviation safety and efficient commercial aircraft routing, 

and Space Shuttle and other rocket launch/landing support, among others. This paper has been 

referenced 94 times in journal articles, and across multiple disciplines, including radio science, 

geophysics, meteorological research, operational meteorology, and optics.

Abstract 

Remote sensing instrumentation has advanced to the point where serious consideration is being 

given to a next-generation tropospheric sounding system that uses radars and radiometers to 

provide profiles of tropospheric variables continuously and automatically. A network of five 

wind-profiling radars has been constructed in Colorado. This network represents a significant 

step in the development of a new observing system for operational and research meteorology. 

The radars and their capabilities and limitations are described.

98
A practical Josephson voltage standard at 1 V 

Clark A. Hamilton, Richard L. Kautz, and Frances L. Lloyd 

 NBS Electromagnetic Technology Division 

IEEE Electron Device Letters, EDL-6: 623–625, 1985 

Significance

The Josephson junction was officially adopted as the basis for precise voltage measurement in 

1972. While early Josephson standards provided the first reference voltage that was stable over 

long periods, they were difficult to use because the voltage generated was only a few millivolts. 

In 1985, Clark Hamilton, Richard Kautz, and Frances Lloyd introduced a new type of Josephson 

voltage standard based on a series array of 1,484 junctions fabricated on a single microchip. The 

original array could be adjusted to produce a variety of voltages up to one volt, and later versions 

with over 14,000 junctions yielded up to 10 V. Array standards have revolutionized voltage 

measurement, making it easier and more accurate, and are now used in government and 

industrial laboratories around the world. 

Abstract 

A series array of 1484 pairs of Josephson junctions, biased by microwaves at 72 GHz, is 

demonstrated to provide stable quantized voltages at the 1 V level. The niobium/lead-alloy 

junctions used in the array are not affected by thermal cycling. 

99
Electron-tunneling experiments using Nb-Sn “break” junctions 

John Moreland and Jack W. Ekin 

 NBS Electromagnetic Technology Division 

Journal of Applied Physics, 58: 3888–3895, November 1985

Significance

Break junctions, the subject of this paper, were originally developed at NIST for tunneling 

spectroscopy studies of certain superconductors to measure energy gap and phonon coupling. 

These materials were difficult to prepare in thin-film form for conventional tunnel junction 

measurements. Several authors have subsequently expanded on break junctions to include 

research on atomic wires and molecular electronics, taking advantage of the adjustable 

subatomic positioning capabilities of the technique. Following the seminal work at NIST, 295 

articles have referenced break junctions in their abstracts, employing concepts originally put 

forth in the 1985 NIST article. Over 50 of these cite the NIST work directly. Tunneling 

spectroscopy and tunnel-junction technology research and theory has led to several Nobel prizes. 

Abstract 

An Nb-Sn filament mounted on a flexible glass beam can be broken to form an electron tunneling 

junction between the fracture elements. Breaking the filament in liquid helium prevents oxidation 

ofthe freshly exposed fracture surfaces. A sharp superconducting energy gap in the I-V

characteristics measured at 4 K indicates the formation of a high-quality tunneling barrier 

between the fracture elements. The resistance of the junction can be continuously adjusted by 

varying the surface bending strain of the beam. An estimated 0.1 nm change in the barrier 

thickness produces about an order of magnitude change in the resistance over the range from 105

to 108 Ω. The exponential character of this dependence shows that the tunnel junction is freely 

adjustable without intimate contact of the junction elements. “Break” junctions made in this way 

offer a new class of tunneling experiments on freshly exposed surfaces of a fractured sample 

without the oxide barrier previously required for junction stability. Such experiments provide a

simple technique for tunneling to new materials and may eliminate complications that can be 

encountered during interpretation of data obtained using oxide barriers. 

100
A comparison of three types of pulse tube refrigerators: New methods for 

reaching 60 K 

Ray Radebaugh, James Zimmerman, David R. Smith, and Beverly Louie 

 NBS Chemical Engineering Science Division 

Advances in Cryogenic Engineering, Vol. 31, pp. 779–789, 1986 

Significance

This paper, published in the proceedings of the 1985 Cryogenic Engineering Conference, 

presented the first results of achieving temperatures below 100 K with a new type of refrigerator 

that was first proposed in Moscow two years earlier. It won the best paper award at the 

conference. This work started a worldwide interest in pulse tube refrigerators, which have 

become the most efficient cryocoolers for temperatures in the range of 60 K to 100 K. These 

refrigerators are now commercially available and are replacing many other types of cryocoolers 

for a wide variety of applications. They have become the most common type of cryocooler to use 

for space applications by the Air Force and by NASA. Many authors of papers on pulse tube

refrigerators reference this paper. 

Abstract

Pulse tube or thermoacoustic refrigerators require only one moving part—an oscillating piston or 

diaphragm at room temperature. Refrigeration occurs within a tube connected to the pressure 

wave generator when the thermal relaxation time between gas and tube is comparable to a half

period. Three types have been discussed in the literature recently by Gifford, by Mikulin, and by 

Wheatley. A record low temperature of 60 K was achieved in our work using a single stage pulse 

tube similar to that of Mikulin. Previously 105 K was the lowest temperature achieved. Because 

of only one moving part, all three types have the potential for long life, but their efficiency and 

intrinsic limitations have never been investigated. This paper compares the three types with each 

other and with common refrigerators such as Joule–Thomson and Stirling refrigerators. An 

apparatus is described which can measure the intrinsic behavior of the different types from

temperatures of about 30 K to 300 K. Overall cycle efficiency as well as sources of loss such as 

conduction and regenerator ineffectiveness are discussed and the advantages of various phase 

shifting techniques to increase refrigeration capacity are compared. 

101
On the depletion of Antarctic ozone 

Susan Solomon 

 NOAA/CIRES Aeronomy Laboratory 

Rolando R. Garcia 

 National Center for Atmospheric Research 

F. Sherwood Rowland 

 Department of Chemistry, University. of California, Irvine 

Donald J. Wuebbles 

 Lawrence Livermore National Laboratory 

Nature, 321(6072): 755–758, 1986 

Significance

In this paper, Dr. Solomon proposed what turned out to be the correct theory of the cause of the 

Antarctic ozone hole and propelled international efforts to protect the ozone layer. 

When the Antarctic ozone hole was discovered in 1986 by the British Antarctic Survey, theories 

abounded as to its cause. Dynamical, chemical, and solar arguments were made. This paper by 

Solomon et al. pointed out that human-produced chlorine compounds could be interacting with 

stratospheric ice clouds and that, in the meteorological setting that is unique to the polar regions, the 

combination of conditions could produce extreme ozone losses. It was a remarkable insight, one 

that required thinking “outside the box” of any one discipline in the atmospheric sciences. 

Chemistry, dynamics, and seasonal meteorology were all critical aspects of the theory. And as it 

turned out, the authors were right. Later observational evidence, gathered by an international team 

of researchers in the National Ozone Expeditions of 1986 and 1987 led by lead author Solomon, 

confirmed the theory advanced by this landmark 1986 Nature paper. This paper and the subsequent 

confirmation of its theory have literally launched a new area of research in atmospheric science: the 

study of chemical reactions occurring on the surfaces of particles. Prior to the discovery of the 

ozone hole, this so-called “heterogeneous chemistry” was a fledgling area of stratospheric research

(a fact that explains why the ozone hole caught the entire research community off guard!). Today, 

the field is transformed and heterogeneous chemistry is recognized as a pivotal factor in ozone 

depletion as well as other atmospheric issues. Lead author Solomon was awarded the 1999 

National Medal of Science by President Clinton in recognition of her achievement, and coauthor 

Rowland received the Nobel Prize for this and other work on the ozone layer. 

Abstract 

Recent observations by Farman et al. reveal remarkable depletions in the total atmospheric ozone 

content in Antarctica. The observed total ozone decreased smoothly during the period from about 

1975 to the present, but only in the spring season. The observed ozone content at Halley Bay was 

~30% lower in the Antarctic spring seasons (October) of 1980–84 than in the springs of 1957–

73. No such obvious perturbation is observable in other seasons, or at other than the very highest 

102
latitude in the Southern Hemisphere, and the magnitude of the observed change there far exceeds 

climatological variability. We present here balloonsonde ozone data which show that these ozone 

changes are largely confined to the region from about 10 to 20 km, during the period August to 

October. We show that homogeneous (gas phase) chemistry as presently understood cannot 

explain these observed depletions. On the other hand, a unique feature of the Antarctic lower 

stratosphere is its high frequency of polar stratospheric clouds, providing a reaction site for 

heterogeneous reactions. A heterogeneous reaction between HCl and ClONO2 is explored as a 

possible mechanism to explain the ozone observations. This process produces changes in ozone 

that are consistent with the observations, and its implications for the behaviour of HNO3 and 

NO2 in the Antarctic stratosphere are consistent with observations of those species there, 

providing an important check on the proposed mechanism. Similar ozone changes are obtained 

with another possible heterogeneous reaction, H2O+ClONO2. 

103
Reducing the risk of refinery explosions: 

1. Examination of a pressure vessel that ruptured at the Chicago refinery of 

the Union Oil Company on July 23, 1984 

Harry I. McHenry, T. Robert Shives, David T. Read, J. David McColskey, Charles H. Brady, and 

Patrick T. Purtscher 

 NBS Fracture and Deformation Division 

NBSIR 86-3049, 1986 

2. Observations of hydrogen damage in a failed pressure vessel 

Harry I. McHenry, Patrick T. Purtscher, and T. Robert Shives 

 NBS Fracture and Deformation Division 

Corrosion Science, 27(10/11): 1041–1057, 1987 

3. Failure analysis of an amine-absorber pressure vessel 

Harry I. McHenry, David T. Read, and T. Robert Shives 

 NBS Fracture and Deformation Division 

Materials Performance, 26(8): 18–24, August 1987 

Background 

In July 1984, an explosion and fire occurred at the Chicago Refinery of Union Oil Company, 

killing 17 people and causing extensive property damage. NBS was requested by the 

Occupational Safety and Health Administration (OSHA) to conduct an investigation into the 

failure of the pressure vessel that eyewitnesses identified as the initial source of the explosion 

and fire. Sections of the vessel were shipped to NBS in August 1985, where a multi-disciplinary 

team, led by Harry McHenry, the Deputy Chief of the Fracture and Deformation Division, 

sought the cause of the failure. Twenty-three NBS staff members participated in the study, from

both Boulder and Gaithersburg. 

Summary of the primary publication 

The study’s findings were published as NBSIR 86-3049. This report outlined the history of the 

vessel and described the steps leading up to its failure. The investigation involved examination of 

the vessel pieces, material property tests, corrosion and hydrogen cracking studies, fracture 

surface observations, and a fracture mechanics assessment. The investigation determined that the 

vessel fractured along a path weakened by extensive cracking adjacent to a repair weld. These 

pre-existing cracks grew through the vessel wall due to hydrogen pressure cracking. When the 

104
depth of the largest of these cracks exceeded 90 to 95 % of the wall thickness, the remaining thin 

ligament of steel in the cracked section ruptured and leakage occured. This crack triggered a 

complete fracture of the vessel circumference at the operating stress level of only 35 MPa 

because the toughness of the vessel steel had been reduced by hydrogen embrittlement. The 

publication identified previously unrecognized interactions between pressure vessel steel, the 

thermal cycles that occur during repair welds, and hydrogen-containing environments. 

Rapid dissemination of the information was important because other vessels might also have 

been at risk of catastrophic failure. In 1986, the report findings were summarized in articles in 

Corrosion Science and Materials Performance, journals that are read by industrial process 

engineers and safety officials in these industries.

Short-term impact 

OSHA recognized the technical complexities involved in assessing the mechanical integrity of 

the various items of equipment used in these industries. To provide OSHA inspectors and 

regulators with the technical information needed, OSHA engaged NIST to perform two 

additional tasks: 

- Prepare an information document titled: “Guidelines for Pressure Vessel Safety 

Assessment” for distribution within OSHA, and 

- Organize and conduct a training course, Course 340 (Hazard Analysis in the Chemical 

Processing Industries), for OSHA inspectors with information lectures concerning 

pressurized equipment. The first course was taught at Boulder in 1988. 

In addition, the reporting of the findings in Corrosion Science and Materials Performance

allowed industrial process engineers and inspection personnel to update the inspection plans for 

plants under their control. Now that they were aware of the conditions found in this study, the 

inspection personnel could search for similar problems (such as hydrogen blisters and cracks) 

during the next annual inspections or shutdowns of processing plants under their control, and 

inspection intervals could be adjusted accordingly. 

Long-term impact 

Several years following the NIST report, OSHA issued a final rule titled “Process Safety 

Management of Highly Hazardous Chemicals, Explosives and Blasting Agents.” This rule was 

published as 29CFR Part 1910 in the Federal Register on February 24, 1991, and became

effective on May 26, 1992. These rules have had a major impact on the process industry; 

particularly those parts that indicated for example, that inspection and testing procedures to 

assess the mechanical integrity of process equipment shall follow recognized and generally good 

engineering practices. These rules have prompted cooperatively funded activities in the process 

and allied industry sectors that focused on the preparation of technical documents that describe 

and define methodology, procedures, and techniques that constitute “recognized and good 

engineering practices.” The first document developed in this activity is expected to be available 

in early 2000. Meanwhile, the OHSA training center continues to offer the training course on 

hazard analysis to its inspectors. It has been held 11 times, and about 230 inspectors have 

attended.

105
Models and observations of the impact of natural hydrocarbons on rural 

ozone

Michael Trainer and Eric J. Williams Eugene J. Allwine and Halvor H. Westberg 

 NOAA Aeronomy Laboratory/CIRES Laboratory for Atmospheric Research 

David D. Parrish Washington State University

 Department of Chemistry Fred C. Fehsenfeld and Shaw C. Liu

 Metropolitan State College NOAA Aeronomy Laboratory 

Martin P. Buhr 

 NOAA Aeronomy Laboratory/CIRES 

Nature, 329(6141): 705–707, 1987 

Significance

Air pollution, or “smog” consists of elevated amounts of ozone, fine particles, and other trace 

species near the earth’s surface. Ozone is formed in the atmosphere by the interaction of nitrogen 

oxides, hydrocarbons, and sunlight. However, in some parts of the country, attempts to improve 

air quality by regulating human-caused emissions of hydrocarbons have been unsuccessful. This 

paper demonstrated that natural sources of hydrocarbons (trees and other vegetation) can be so 

large that human emissions are (relatively) insignificant. The results suggested that controlling 

human emissions of other compounds, e.g., the nitrogen oxides, would be more effective in 

reducing surface-level ozone pollution. Subsequent research has identified regions in the 

country, primarily in the southeastern U.S., where natural hydrocarbons are more abundant than 

had been recognized. The use of scientifically customized approaches to air quality management 

has led to greater improvements in air quality for many regions of the nation. 

Abstract

Large quantities of non-methane hydrocarbons (NMHCs) are emitted into the atmosphere from

vegetation. A recent inventory of Lamb et al., indicates that the emissions of natural 

hydrocarbons is significant compared to that of anthropogenic NMHCs in most regions of the 

United States. Because of their chemical activity, the natural NMHCs can play important parts in 

the formation of trace gases, such as ozone (O3), peroxyacetyl nitrate (PAN) and oxygenated 

secondary hydrocarbons, which contribute to regional-scale air pollution and may be harmful to 

crops and forest. The impact of natural hydrocarbons on the formation of O3 in the atmosphere 

has been discussed previously. In general, it has been concluded that their impact is small. But 

lack of data on the ambient concentrations of key photochemical species and an incomplete 

analysis of the photochemistry has prevented a definitive evaluation of the impact of natural 

NMHCs on rural O3. Here we report on concentrations of key trace gases measured concurrently 

at a rural site in the eastern USA during the summer of 1986 and a modelling study conducted to 

analyze these measurements. This study demonstrated that natural NMHCs can have a 

significant impact on ozone formation in rural air. 

106
Second viscosity and thermal conductivity virial coefficients of gases: 

Extension to low reduced temperature 

James C. Rainwater and Daniel G. Friend 

 NBS Thermophysics Division 

Physical Review A, 36: 4062–4066, 1987 

Significance

The ability to predict the properties of fluids from first principles, whether using quantum

mechanics or classical approaches, remains an elusive goal. Some rigorous results are available, 

but a systematic approach based on density expansions—a virial series—had not been successful 

for transport properties. This paper showed how to account for particle interactions in the first 

transport property virial coefficients, even at low reduced temperature. It was published in part to 

explain some recent (1986) measurements on the viscosity of two specific vapors (benzene and 

methanol), but has since been used as the basis for describing the viscosity surface of many 

vapors. The theoretical techniques have evolved into practical methods of describing empirical 

data, and the ideas have now been incorporated in several international standards. 

Abstract

A recent theory of the initial density dependences of both viscosity and thermal conductivity has 

been extended to include lower reduced temperatures. New data on the second viscosity virial 

coefficients of some organic vapors are found to be in substantial agreement with the theory even 

at the lowest temperatures. We present in tabular form the numerical values for both transport 

virial coefficients in the reduced temperature range 0.5 ≤ T* ≤ 100 and include values for the 

constituent two-monomer, three-monomer, and monomer-dimer contributions. A brief discussion 

of the theoretical approach and calculational methods is also given. 

107
Tunneling spectroscopy of a La-Sr-Cu-O break junction: Evidence for strong 

coupling superconductivity 

John M. Moreland, Alan F. Clark, and Loren F. Goodrich 

NBS Electromagnetic Technology Division 

Harry C. Ku and R.N. Shelton 

 Ames Laboratory and Physics Department 

 Iowa State University, Ames, Iowa 

Physical Review B 35(16): 8711–8713, June 1987 

Significance

This is the report of the first observation and measurement of the energy gap in a high critical 

temperature superconductor (HTS). These unique materials were discovered by the Nobel Prize 

winners, Bednorz and Mueller, in late 1986 and first revealed in backroom discussions at the 

Materials Research Society meeting in December 1986. With just a few materials urgently 

developed by colleagues at Iowa State University (the coauthors Ku and Shelton), this group of 

NBS researchers quickly adapted a measurement technique developed by John Moreland to 

make the first determination of the superconducting energy gap in any HTS material. This 

established the certainty of superconductivity and determined the nature and magnitude of this 

most important physical parameter of superconductivity. The authors were selected to be some of

the few to report their measurements at the now famous 1987 “March Meeting” of the American 

Physical Society where thousands of physicists literally scrambled over each other for seats to 

hear these exciting results. This Physical Review article summarizes the verbally reported results

and outlines their relevance to the now accepted high temperature superconductors. The work led 

to a DOC Silver Medal and APS Fellowship. 

Abstract 

Detailed structure in the quasiparticle tunneling has been observed in La-Sr-Cu-O 

superconductive tunneling junctions using the break-junction technique. Variability in the energy 

gap and associated structure in the current-voltage curves are observed indicating significant 

inhomogeneity in the superconducting properties. Large energy gaps (7.0 meV) and deep 

structure in the conductance derivative are evidence for a strong-coupling mechanism. 

108
Error analysis techniques for planar near-field measurements 

Allen C. Newell 

 NBS Electromagnetic Fields Division 

IEEE Transactions on Antennas and Propagation AP-36: 754–768, June 1988 

Significance

This work is the model from which most uncertainty evaluations of near-field measurements are 

derived. The paper received the “S.A. Schelkunoff Award” in 1989 and the “W.R.G. Baker 

Award” in 1990. These are the best paper awards of the IEEE Antennas and Propagation Society 

and the overall IEEE, respectively. 

Abstract 

The results of an extensive error analysis on planar near-field measurements are described. The 

analysis provides ways for estimating the magnitude of each individual source of error and then 

combining them to estimate the total uncertainty in the measurement. Mathematical analysis, 

computer simulation, and measurement tests are all used where appropriate. 

109
Josephson-junction model of critical current in granular Y1Ba2Cu3O7–δ

superconductors 

Robert L. Peterson and Jack W. Ekin

 NBS Electromagnetic Technology Division 

Physical Review B, 37: 9848–9851, June 1988 

Significance

While ceramic high-temperature superconductors (HTS) were being intensely investigated in the 

late 1980s, it seemed that their transport critical currents were strongly affected by “weak links” 

that blocked the flow of supercurrents at very low magnetic fields. However, no quantitative 

theory existed to explain the experimental evidence and support the hypothesis. Peterson and 

Ekin presented the first quantitative evidence that identified grain-boundary weak links as the 

source of the transport current problem. This often-cited paper showed that all earlier 

experimental results—including the pioneering measurements of Ekin et al. (Journal of Applied 

Physics, vol. 62, pp. 4821–4828, 1987)—could, in fact, be quantitatively explained in terms of a 

grain-boundary Josephson-tunneling weak-link model with no adjustable parameters. The grainboundary weak-link effect has dominated much of the research on HTS materials ever since. It 

has become the principal consideration in the development of practical HTS conductors 

Abstract 

We calculate the transport critical-current density in a granular superconductor in magnetic fields 

below about 5 × 10–3 T. The field dependence in this region is assumed to be controlled by 

intragranular or intergranular Josephson junctions. Various model calculations are fitted to 

transport critical-current data on bulk Y1Ba2Cu3O7–δ ceramic superconductors, whose average 

grain size somewhat exceeds 10 μm. The results yield an average junction cross-sectional area 

(thickness × length) of 4–6 μm2. If the junctions are at the grain boundaries, a London 

penetration depth of about 150–300 nm is inferred, consistent with other estimates. We conclude 

that Josephson junctions are limiting the transport current in these samples and that they lie at the 

grain boundaries. The parameters of the fit are not consistent with Josephson junctions at 

twinning boundaries. 

110
Handbook of basic tables for chemical analysis 

Thomas J. Bruno and Paris D.N. Svoronos 

 NIST Thermophysics Division 

CRC Press, Boca Raton, FL, 1989 

Significance

This important handbook, whose second edition was published in 2003, is one of the most highly 

cited references in the field of chemical analysis. The book was an outgrowth of materials 

prepared for a course on chemical instrumentation presented in the Boulder Laboratories, and 

covers the classical fields of chromatography, spectroscopy, and chemical (wet) methods. The 

tables, notes, spectra, and references in this handbook provide a compact and complete set of 

information used in analytical laboratories throughout the world. 

Abstract (since this book has no abstract, an excerpt from the Preface is included)

... Although there have been considerable changes since the first version of the tables, the aim

has remained essentially the same. We have tried to provide a single source of information for 

those practicing scientists and research students who must use various aspects of chemical 

analysis in their work. In this respect, it is geared less toward the researcher in analytical 

chemistry than to those practitioners in other chemical disciplines who must make routine use of 

chemical analysis. We have given special emphasis to those “instrumental techniques” which are 

most useful in solving common analytical problems. In many cases, the tables contain 

information gleaned from the most current research papers and provide data not easily obtainable 

elsewhere. In some cases, data are presented which are not available at all in other sources. An 

example is the section covering supercritical fluid chromatography, in which a tabular P-ρ-T 

surface for carbon dioxide has been calculated (specifically for this work), using an accurate 

equation of state ... . 

111
MPM—An atmospheric millimeter-wave propagation model 

Hans J. Liebe 

 NTIA Institute for Telecommunication Sciences 

International Journal of Infrared and Millimeter Waves, 10 (6): 631–650, 1989 

Significance

This paper is one of the most inclusive publications of a body of work that produced 

measurements and models of millimeter wave propagation that remain today unmatched in 

accuracy. This article introduces MPM, a model for complex refractivity of a clear atmosphere 

below 1 THz. It incorporates the quantum effects of molecular oxygen and other atmospheric 

constituents to describe propagation effects (delay and loss) and their dependencies on 

temperature, pressure, humidity, and composition. This work defined atmospheric absorption for 

a broad piece of the radio spectrum for such applications as remote sensing technology. Fifteen 

years after this work was published, MPM is still considered an international standard and is 

widely used.

Abstract 

A broadband model for complex refractivity is presented to predict propagation effects of loss 

and delay for the neutral atmosphere at frequencies up to 1000 GHz. Contributions from dry air, 

water vapor, suspended water droplets (haze, fog, cloud), and rain are addressed. For clear air, 

the local line base (44 O2 plus 30 H2O lines) is complemented by an empirical water-vapor 

continuum. Input variables are barometric pressure, temperature, relative humidity, suspended 

water droplet concentration, and rainfall rate. 

112
Performance standards for packet-switched services 

Neal B. Seitz 

 NTIA Institute for Telecommunication Sciences 

Proceedings of the IEEE International Communications Conference, 63–70, June 1989 

Significance

This paper describes a family of CCITT (now ITU-T) Recommendations, developed under 

NTIA/ITS leadership, that collectively standardize performance metrics and worst-case 

performance values for international packet-switched services using the X.25/X.75 protocols. 

The standard metrics have been implemented in network management systems and stand-alone 

test equipment and the recommended performance values have been used in planning, designing, 

operating, and maintaining first generation packet switched networks in many countries. The 

performance specification and measurement concepts described in the paper provided the 

framework for over a dozen subsequent national and international data network performance 

standards, including, most recently, an ITU-T Recommendation defining standard Quality of 

Service (QoS) classes for IP-based networks. 

Abstract 

Four new Recommendations on the performance of international packet-switched services were

developed in CCITT Study Group VII during the 1985–1988 Study Period. Recommendation 

X.134 defines apportionment boundaries and packet layer reference events which provide a basis 

for performance description. The boundaries are physical interfaces at which CCITT 

Recommendation X.25 or X.75 procedures are used, and the events are corresponding interface 

state transitions. Recommendations X.135, X.136, and X.137 define specific packet-switched 

service performance parameters and associated values. The parameters are measures of packetswitched service speed, accuracy, dependability, and availability applicable to end-to-end virtual 

connections and their component sections. The values are worst-case performance limits for the 

national and international portions of an international virtual connection. It is anticipated that 

these performance parameters and values will be widely used in the planning and operation of 

packet-switched services supporting international data communications. The approach used in 

developing the packet-switched service parameters has been adapted for use in developing 

performance parameters for Integrated Services Digital Networks (ISDNs).

113
Stainless steel weld metal: Prediction of ferrite content 

Chris N. McCowan, Thomas A. Siewert, and D.L. Olson 

 NIST Materials Reliability Division 

Welding Research Council Bulletin 342, April 1989 

Significance

The ferrite content of austenitic stainless steel welds must be tightly controlled. Welds that are 

too low in ferrite may exhibit hot cracking, while those that are too high may exhibit poor 

corrosion performance or cause stray magnetic fields in magnetic applications. While there are 

various techniques to measure the ferrite content in the final product, most engineers prefer to 

avoid problems from the very beginning, by choosing materials and procedures based on 

accurate predictions. The procedures and graph in this report have been adopted by many codes 

and standards, such as the ASME Boiler and Pressure Vessel Code. The American Welding 

Society selected a summary of this procedure for the 1989 McKay Helm Award, for “a 

significant advancement in the knowledge of stainless weld metals.” 

Abstract

A new diagram to predict the ferrite number (FN) in stainless steel welds is proposed in this 

Bulletin. The diagram has a range from 0 to 100 FN and more accurately predicts the ferrite 

content for welds having a FN less than 18. The database contains over 950 welds and is 

included as an appendix to the report. 

Publication of this report, WRC Bulletin No. 342 was sponsored by the Subcommittee on 

Welding Stainless Steel of the High Alloys Committee of the Welding Research Council. 

114
The accuracy of RASS temperature measurements 

Peter T. May, Kenneth P. Moran, and Richard G. Strauch 

 NOAA Wave Propagation Laboratory 

Journal of Applied Meteorology, 28(12): 1329–1335, December 1989 

Significance

A Radio Acoustic Sounding System, or RASS, is a novel technique for remotely profiling 

temperature in the atmosphere. It uses clear-air Doppler radar technology to measure the speed 

of an upward propagating acoustic wave, which can be processed to yield a profile of the virtual 

temperature. Although the RASS concept was first proposed in the 1960s, successful 

implementations of the technology by various international research groups were delayed until 

the late 1970s and early 1980s because of hardware limitations. In the late 1980s, researchers at 

NOAA’s Aeronomy Laboratory realized that this technique could be easily implemented on 

existing wind profiler radars that relied on scatter from clear-air turbulence to infer atmospheric 

winds. Subsequent work by NOAA’s Environmental Technology Laboratory advanced the 

RASS technology to a point where it could be transitioned to the operational community. The 

cited paper represents a critical step towards the acceptance of RASS as a viable and important 

remote sensing tool. The authors performed a statistical study assessing the utility of the 

technique for meteorological studies by comparing RASS and radiosonde temperature 

measurements over extended periods during the summer and winter months of 1988 through 

1989. Their study showed that the RASS technique yields temperature measurements 

comparable in accuracy with radiosonde observations, the current standard. Their conclusion led 

to the rapid adoption of the RASS technique by NOAA’s Wind Profiler Demonstration Network. 

Tropospheric wind and temperature information can now be routinely retrieved using a large 

number of wind profiler/RASS installations across the country. 

Abstract 

Temperature measurements obtained using radiosondes and Radio Acoustic Sounding Systems 

(RASS) are compared to assess the utility of the RASS technique for meteorological studies. The 

agreement is generally excellent; rms, temperature, differences are about 1.0°C for comparisons 

during a variety of meteorological conditions. Observations taken under ideal circumstances 

indicate that a precision of about 0.2°C is achievable with the RASS technique. A processor 

being designed for RASS should allow routine temperature measurements approaching this 

precision. 

115
Automated Computer Time Service: 

1. The NIST Automated Computer Time Service 

Judah Levine, Marc Weiss, Dickie D. Davis, David W. Allan, and D.B. Sullivan 

 NIST Time and Frequency Division 

NIST Journal of Research, 94(5): 311–321, September–October, 1989 

2. Time synchronization using the Internet 

Judah Levine 

 NIST Time and Frequency Division 

IEEE Transactions on Ultrasonic Ferromagnetics, 45: 450–460, March 1, 1998 

Significance

These two papers describe unique NIST services initiated to meet demand for accurate time for 

computers, networks, and electronic information exchange. The explosion of the use of 

computers and networks in the 1980s and 1990s fundamentally changed the way information is 

exchanged for commerce, defense, science, and many other applications. Accurate and reliable 

timing became crucial for both the functioning of the networks and for accurately and traceably 

ordering electronic transactions. 

NIST’s Judah Levine was one of the first people to both recognize this need and develop 

practical and easy-to-use solutions. The first paper describes a system initiated in the 1980s to 

synchronize computers and other electronic devices to NIST time using an automated dialup 

system and free client software provided by NIST. This Automated Computer Time Service 

(ACTS) immediately became a crucial tool for information technology applications and grew 

rapidly with very little publicity on NIST’s part. 

Levine also anticipated early the impact of the Internet and initiated in the early 1990s a similar 

service using the Internet and free client software to automatically synchronize computer clocks 

and other networked devices to NIST time. This Internet Time Service (ITS) grew even more 

rapidly than the Internet itself. Today NIST processes more than 1 billion ITS requests for NIST 

time every day, with demand doubling about every 10 months since the service was introduced. 

The NIST software is free, but dozens of companies now provide their own versions of the 

software using ITS. The National Association of Securities Dealers (NASD) Order Audit Trail 

System requires that all of the electronic NASDAQ transactions be time-stamped to NIST time, 

involving more than 600,000 companies and tens of billions of dollars in transactions each day, 

and ACTS and ITS are the primary sources for complying with these regulations. NIST time 

provided through ITS and ACTS is by many orders of magnitude the most heavily and broadly 

used NIST service, and arguably the service with the largest direct economic impact. 

116
Abstract 1 

The NIST Automated Computer Time Service (ACTS) is a telephone time service designed to 

provide computers with telephone access to time generated by the National Institute of Standards 

and Technology at accuracies approaching 1 ms. Features of the service include automated 

estimation by the transmitter of the telephone-line delay, advanced alert for changes to and from

daylight saving time, and advanced notice of insertion of leap seconds. The ASCII-character 

time code operates with most standard modems and computer systems. The system can be used 

to set computer clocks and simple hardware can also be developed to set non-computer clock 

systems. 

Abstract 2 

This paper discusses a new algorithm for synchronizing the clocks of networked computers using 

messages transmitted over the network itself. The design is based on a statistical model of the 

clock and the network, and uses this model to define the parameters of a frequency-lock loop 

which is used to discipline the local oscillator. The design was tested by synchronizing a 

standard workstation to a time server located 1200 km away; the time offset between the clock 

synchronized in this way and UTC is 2 ms rms. This analysis also can be used to design 

algorithms that provide lower accuracy at lower cost. 

117
118
Papers from the 1990s 

Improved technique for determining complex permittivity with the transmission/reflection 

method 

 James Baker-Jarvis, Eric J. Vanzura, and William Kissick, 1990 122 

Observational constraints on the global atmospheric CO2 budget 

 Pieter Tans, Inez Fung, and Taro Takahashi, 1990 123 

Alternating-field susceptometry and magnetic susceptibility of superconductors 

 Ron B. Goldfarb, Curt A. Thompson, and Mark Lelental, 1991 

 124 

A model for the complex permittivity of water at frequencies below 1 THz 

 Hans J. Liebe, George A. Hufford, and Takeshi Manabe, 1991 125 

An isentropic three-hourly data assimilation system using ACARS aircraft observations 

 Stanley G. Benjamin, Keith A. Brewster, Renate Brümmer, Brian F. Jewett, 

 Thomas W. Schlatter, Tracy L. Smith, and Peter A. Stamus, 1991 126 

Characteristic impedance determination using propagation constant measurement 

 Roger B. Marks and Dylan F. Williams, June 1991 127 

Slowing down of the global accumulation of atmospheric methane during the 1980s 

 L. Paul Steele, Edward J. Dlugokencky, Patricia M. Lang, Pieter P. Tans, Russell C. 

 Martin, and Kenneth A. Masarie, 1992 128 

A new method for measuring the strength and ductility of thin films 

 David T. Read and James W. Dally, 1993 129 

Atmospheric lifetimes of long-lived halogenated species 

 Akkihebbal R. Ravishankara, Susan Solomon, Andrew A. Turnipseed, 

and Rachel F. Warren, 1993 130 

Decrease in the growth rates of atmospheric chlorofluorocarbons 11 and 12 

 James W. Elkins, Thayne M. Thompson, James H. Butler, Bradley D. Hall, Thomas H. 

 Swanson, Scott O. Cummings, Donald A. Fisher, and A.G. Raffo, 1993 131 

Electron beam moiré 

 James W. Dally and David T. Read, 1993 132 

Optical fiber geometry: Accurate measurement of cladding diameter 

 Matt Young, Paul D. Hale, and Steven E. Mechels, 1993 133 

119
REFPROP Refrigerant Properties Database: Capabilities, limitations, and future directions 

 Mark O. McLinden, John G. Gallagher, Marcia L. Huber, 

and Graham Morrison, 1993 134 

Surface climate variations over the North Atlantic Ocean during winter: 1900–89 

 Clara Deser and Maurice L. Blackmon, 1993 135 

Welding for cryogenic service 

Thomas A. Siewert and Chris N. McCowan, 1993 136 

Metrological accuracy of the electron pump

 John M. Martinis and Michael Nahum, 1994 137 

Response of the thermosphere and ionosphere to geomagnetic storms

 Tim J. Fuller-Rowell, Mihail V. Codrescu, R.J. Moffett, and Shaun Quegan, 1994 138 

A mechanism for the recurrence of wintertime midlatitude SST anomalies during winter 

 Michael A. Alexander and Clara Deser, 1995 140 

Analog-to-digital converters and their applications in radio receivers 

Jeffery A. Wepman, 1995 141 

Demonstration of a fundamental universal quantum logic gate 

 Chris Monroe, Dawn M. Meekhof, Brian E. King, Wayne M. Itano, and 

David J. Wineland, 1995 142 

The optimal growth of tropical sea surface temperature anomalies 

 Cécile Penland and Prashant D. Sardeshmukh, 1995 143 

A “Schrödinger cat” superposition state of an atom

 Chris Monroe, Dawn M. Meekhof, Brian E. King, and David J. Wineland, 1996 144 

Solidification sensing using high-energy x-ray diffraction 

 Thomas A. Siewert, William P. Dubé, and Dale W. Fitting, 1996 145 

X-ray detection using a superconducting transition-edge sensor microcalorimeter with 

electrothermal feedback 

 Kent D. Irwin, Gene C. Hilton, David A. Wollman, and John M. Martinis, 1996 146 

Arctic environmental change of the last four centuries 

 Jonathan T. Overpeck, Konrad Hughen, Douglas Hardy, Raymond Bradley, Roslyn Case, 

 Maryanne Douglas, Bruce Finney, Konrad Gajewski, Gordon Jacoby, Anne Jennings, 

 Scott Lamoureux, Andrew Lasca, Glen MacDonald, Jay Moore, Michael Retelle,

 Sheldon Smith, Alex Wolfe, and Gregory Zielinski, 1997 147 

120
El Niño, La Niña, and the nonlinearity of their teleconnections 

 Martin P. Hoerling, Arun Kumar, and Min Zhong, 1997 149 

Isochoric ( p, ρ,T) measurements for five natural gas mixtures from 

T = (225 to 350) K at pressures to 35 MPa 151 

 Joseph W. Magee, William M. Haynes, and Michael J. Hiza, 1997 

Mapping city lights with nighttime data from the DMSP Operational Linescan System

 Christopher D. Elvidge, Kimberly E. Baugh, Eric A. Kihn, Herbert W. Kroehl, and 

Ethan R. Davis, 1997 152 

Electromagnetic theory of reverberation chambers 

David A. Hill, 1998 153 

2000 years of drought variability in the central United States 

 Connie A. Woodhouse and Jonathan T. Overpeck, 1998 154 

A capacitance standard based on counting electrons 

 Mark W. Keller, Ali L. Eichenberger, John M. Martinis, 

and Neil M. Zimmerman, 1999 155 

For 100 years, notched bar impact testing standards have yielded widespread 

benefits for industry 

 Michael P. Manahan, Chris N. McCowan, Thomas A. Siewert, John M. Holt, 

 Francis J. Marsh, and Earl A. Ruth, 1999 156 

Objective estimation of perceived speech quality

Part I: Development of the measuring normalizing block technique 

Part II: Evaluation of the measuring normalizing block technique 

Stephen Voran, 1999 157 

121
Improved technique for determining complex permittivity with the 

transmission/reflection method 

James Baker-Jarvis, Eric J. Vanzura, and William Kissick 

 NIST Electromagnetic Fields Division 

IEEE Transactions on Microwave Theory and Techniques, 38(8): 1096–1101, 1990 

Significance

This paper developed a new method for determining the permittivity from transmission-line 

scattering data. This new stable method for permittivity determination eliminated the instabilities 

that plagued the commonly used Nicolson–Ross method. The paper has been widely acclaimed 

as a breakthrough in transmission line permittivity measurements. 

Abstract 

The transmission/reflection method for complex permittivity and permeability determination is 

studied. The special case of permittivity measurement is examined in detail. New robust 

algorithms for permittivity determination that eliminate the ill-behaved nature of the commonly 

used procedures at frequencies corresponding to integer multiples of one-half wavelength in the 

sample are presented. An error analysis is presented which yields estimates of the error incurred 

due to the uncertainty in scattering parameters, length measurement, and reference plane 

position. In addition, new equations are derived for determining complex permittivity 

independent of reference plane position and sample length. 

122
Observational constraints on the global atmospheric CO2 budget

Pieter Tans 

 NOAA Climate Monitoring and Diagnostics Laboratory 

Inez Fung 

 National Atmospheric and Space Administration 

Taro Takahashi 

 Columbia University

Science, 247: 1431–1438, 1990 

Significance

This paper showed that North America was a potential sink for large amounts of CO2 that led to 

a completely new way of thinking about the global carbon cycle. It was used as an underpinning 

for the growing North American Carbon Cycle Research Program, the largest and most 

expensive global climate change research program on earth. 

Abstract

Observed atmospheric concentrations of CO2 and data on partial pressures of CO2 in surface 

ocean waters are combined to identify globally significant sources and sinks of CO2. The 

atmospheric data are compared with boundary layer concentrations calculated with the transport 

field generated by a general circulations model (GCM) for specified source-sink distributions. In 

the model, the observed north-south atmospheric concentration gradient can be maintained only 

if the sinks for CO2 are greater in the Northern than in the Southern Hemisphere. The observed 

differences between the partial pressures of CO2 in the surface waters of the Northern 

Hemisphere and the atmosphere are too small for the oceans to be the major sink of fossil fuel 

CO2. Therefore, a large amount of the CO2 is apparently absorbed on the continents by terrestrial 

ecosystems. 

123
Alternating-field susceptometry and magnetic susceptibility of 

superconductors 

Ron B. Goldfarb and Curt A. Thompson 

 NIST Electromagnetic Fields Division 

Mark Lelental 

 Eastman Kodak Company

NIST Internal Report 3977, October 1991; also published in Magnetic Susceptibility of 

Superconductors and Other Spin Systems, R.A. Hein, T.L. Francavilla, and D.H. Liebenberg, 

editors. New York: Plenum Press, 1991, pp. 49–80 

Significance

This monograph is a thorough analysis of alternating-field susceptometry applied to 

superconductors. It has been cited widely as a comprehensive and authoritative guide to 

magnetic susceptibility measurements. Susceptometry has become a standard method for 

characterizing “weak-link” connected superconductors. The measurements and results have been 

replicated and used in laboratories throughout the world. Magnetic instrument manufacturers 

have reprinted it as “Tech Notes” for their customers. 

Abstract 

This review critically analyzes current practice in the design, calibration, sensitivity 

determination, and operation of alternating-field susceptometers, and examines applications in 

magnetic susceptibility measurements of superconductors. Critical parameters of the intrinsic 

and coupling components of granular superconductors may be deduced from magnetic 

susceptibility measurements. The onset of intrinsic diamagnetism corresponds to the initial 

decrease in electrical resistivity upon cooling, but the onset of intergranular coupling coincides 

with the temperature for zero resistivity. The lower critical field may be determined by the field 

at which the imaginary part of susceptibility increases from zero. Unusual features in the 

susceptibility of superconductor films, such as a magnetic moment that is independent of film

thickness and the variation of susceptibility with angle, are related to demagnetization.

Demagnetizing factors of superconductor cylinders are significantly different from those 

commonly tabulated for materials with small susceptibilities. Rules for the susceptibility of

mixtures with specific demagnetizing factors are used to estimate the volume fraction of 

superconducting grains in sintered materials. Common misunderstandings of the Meissner effect, 

magnetic units, and formula conversions are discussed. There is a comprehensive summary of

critical-state formulas for slabs and cylinders, including new equations for complex susceptibility 

in large alternating fields. Limitations on the use of the critical-state model for deducing critical

current density are listed and the meaning of the imaginary part of susceptibility is considered. 

124
A model for the complex permittivity of water at frequencies 

below 1 THz

Hans J. Liebe and George A. Hufford 

 NTIA Institute for Telecommunication Sciences 

Takeshi Manabe 

 ATR Optical and Radio Communications Research Laboratories, Japan 

International Journal of Infrared and Millimeter Waves, 12(7): 659–675, 1991 

Significance

The dielectric properties (i.e., complex permittivity) of liquid water at atmospheric temperatures

play a key role in computations of atmospheric propagation and remote sensing effects caused by 

raindrops and by droplets suspended in fog or clouds. Also, systems that operate in the nearmillimeter-wave (NMW, 0.1 THz to 1 THz) frequency range experience much less loss than 

those utilizing infrared/optical frequencies in inclement weather and it is useful to have a reliable 

model to compute the advantage. This model substantially improved on the existing standard 

model (Ray, 1972) by utilizing both a considerable body of new experimental evidence and a 

simplified and more accurate double Debye (i.e., relaxation) term model formulation for the 

dielectric properties. The improved model, although developed primarily for use with the ITS 

millimeter wave propagation model (MPM, see Liebe, 1989, this volume), is widely recognized 

and has been embraced by a wide range of atmospheric science researchers and communications

engineers. 

Abstract 

Experimental permittivity data of liquid water, compiled from the open literature, were 

selectively applied to support a modeling strategy. Frequencies up to 1 THz and atmospheric 

temperatures are covered with an expression made up by two relaxation (Debye) terms. The 

double-Debye model reduces to one term when the high frequency limit is set at 100 GHz, and 

the model can be extended to 30 THz by adding two resonance (Lorentzian) terms. The scheme

was carried out by employing nonlinear least-squares fitting routines to data we considered 

reliable. 

125
An isentropic three-hourly data assimilation system using ACARS aircraft 

observations

Stanley G. Benjamin Brian F. Jewett 

 NOAA Forecast Systems Laboratory University of Illinois, Champaign, IL

Keith A. Brewster Thomas W. Schlatter 

 University of Oklahoma, Norman, OK NOAA Forecast Systems Laboratory 

Renate Brümmer Tracy L. Smith and Peter A. Stamus 

 Deutsche Forschungsanstalt für Luft- und Cooperative Institute for Research 

 Raumfahrt, Cologne, Germany in the Atmosphere 

Monthly Weather Review, 119: 888–906, 1991 

Significance

The Mesoscale Analysis and Prediction System (MAPS) described in this paper made it possible 

to produce maps of surface and upper air weather conditions and, from them, generate short-term 

forecasts at three-hour intervals. Prior to this time, computer forecasts were started only at 0000 

and 1200 GMT, following weather balloon launches. Observations made at other times were 

largely ignored. The frequent updating of analyses and forecasts led to improved guidance for 

commercial flight planning and local weather services. Also, the use of isentropic coordinates 

(surfaces of constant potential temperature) led to better predictions near the tropopause and in 

the vicinity of warm and cold fronts. MAPS, developed with the cooperation of the National 

Meteorological Center (NMC), was the forerunner of the Rapid Update Cycle (RUC), 

implemented operationally in 1994 and still running—today on an hourly cycle. MAPS and the 

RUC are examples of effective technology transfer. Forecasters at National Weather Service 

Offices use the RUC for short-range guidance; the Storm Prediction Center uses it routinely for 

severe weather watches; the Aviation Weather Center uses it for aviation weather advisories; the 

FAA uses it for estimating weather constraints on air traffic flow. 

Abstract

A 3-h intermittent data assimilation system (MAPS) configured in isentropic coordinates was 

developed and implemented in real-time operation. The major components of this system are 

data ingest, objective quality control of the observations, objective analysis of the observations 

on a grid, and a primitive equation forecast model, all using isentropic coordinates. The primary 

data sources for this system are automated aircraft reports, wind profilers, surface observations, 

and rawinsonde balloons. Three-hour forecasts from MAPS incorporating the aircraft reports 

improve on 12-h MAPS forecasts valid at the same time for all levels and variables, and also 

improve on 12-h NMC forecasts of upper level winds. This result is due to frequent updating, 

here demonstrated for the first time, the quality and volume of the aircraft data, and the 

effectiveness of the isentropic data assimilation used. 

126
Characteristic impedance determination using propagation constant 

measurement 

Roger B. Marks and Dylan F. Williams

 NIST Electromagnetic Fields Division 

IEEE Microwave and Guided Wave Letters, 1(6): 141–143, June 1991 

Significance

This paper developed the first accurate and straightforward method of measuring the frequency 

dependent characteristic impedance of on-wafer transmission lines. The method enables the onwafer TRL calibration, which, thanks to this work, has become the reference calibration to which 

all others are compared. 

Abstract 

A method is demonstrated whereby the characteristic impedance of transmission lines may be 

easily determined from a measurement of the propagation constant. The method is based on a 

rigorous analysis using realistic approximations to account for the effects of imperfect 

conductors. Numerical studies indicate that high accuracy is possible, and experiments using 

coplanar waveguide demonstrate the advantage of the method in the interpretation of Sparameters. 

127
Slowing down of the global accumulation of atmospheric methane during the 

1980s

L. Paul Steele 

 NOAA Climate Monitoring and Diagnostics Laboratory/CIRES/CSIRO Australia 

Edward J. Dlugokencky 

 NOAA Climate Monitoring and Diagnostics Laboratory/CIRES 

Patricia M. Lang and Pieter P. Tans 

 NOAA Climate Monitoring and Diagnostics Laboratory 

Russell C. Martin and Kenneth A. Masarie 

 NOAA Climate Monitoring and Diagnostics Laboratory/CIRES 

Nature, 358: 313–316, 1992 

Significance

This was the first study to show that the rate of increase of methane, which had been steadily 

increasing since the beginning of the industrial revolution, was unexpectedly decreasing. This 

discovery was made through study of the long-term atmospheric trace gas concentration data 

collected on a global scale by the decades-old CMDL cooperative flask sampling program. 

Methane is second only to carbon dioxide in its anthropogenic influence on climate, contributing 

about 20 % of the total increase in radiative forcing by long-lived greenhouse gases. It is also 

important in determining the cleansing capacity of the troposphere. The atmospheric burden of 

methane increased by a factor of 2.5 from pre-industrial times to the early 1980s. Until this 

paper, most scientists thought that the rate of increase of atmospheric methane would continue to 

grow as global population increased. This work showed that the growth of population and 

methane emissions had unexpectedly become decoupled. This discovery has resulted in 

downward revisions to estimates of the future rate of increase in atmospheric methane used to 

predict climate change, possibly the greatest challenge to society in this century. 

Abstract

Measurements of methane in modern air and in air trapped in ice cores have shown convincingly 

that the abundance of atmospheric methane has been rising since the Industrial Revolution. This 

is a matter of concern because of the important role of methane in determining the radiative 

balance and chemical composition of the atmosphere. The causes of this increase have not been 

identified unambiguously because of uncertainties in our understanding of the global budget of 

atmospheric methane and in how it is changing with time. Here we report on measurements of 

atmospheric methane from an extensive global network of flask sampling sites, which reveal 

that, although methane continues to accumulate in the atmosphere, there has been a substantial 

slowing of the global accumulation rate between 1983 and 1990. If this deceleration continues 

steadily, global methane concentrations will reach a maximum around the year 2006. Our results 

hint that changes in methane emissions in the latitude band 30–90-degrees N may be of 

particular significance to this trend.

128
A new method for measuring the strength and ductility of thin films 

David T. Read 

 NIST Materials Reliability Division 

James W. Dally 

 Mechanical Engineering Department, University of Maryland 

Journal of Materials Research 8: 1542–1549, July 1993 

Significance

This paper was our first publication on mechanical properties of thin films. It marks the 

beginning of the effort at NIST to develop mechanical property measurements for thin films used 

in microelectronic devices. This paper was the beginning of our attempt to push the size of 

mechanical test specimens down toward the actual size of films used in electronic devices. 

Abstract 

A new method of measuring the mechanical strength of thin films is described. We prepare 

miniature arrays of four tensile specimens, each 0.25 mm wide, 1 mm long, and 2.2 μm thick, 

using deposition, patterning, and etching processes common to the semiconductor industry. Each 

array of four specimens is carried on and protected by a rectangular silicon frame. Thirty-six 

such specimens are produced on a single wafer. After a specimen frame is mounted, its vertical 

sides are severed without damaging the specimens. The load is applied by micrometers through a 

special tension spring. Tensile properties of a 2.2 μm thick Ti-Al-Ti film were determined. 

129
Atmospheric lifetimes of long-lived halogenated species

Akkihebbal R. Ravishankara, Susan Solomon, Andrew A. Turnipseed, and Rachel F. Warren 

 NOAA Aeronomy Laboratory 

Science, 259: 194–199, 1993 

Significance

Perfluorocarbons (PFCs) are a class of compounds that were being considered as replacements 

for the now-banned ozone-destroying chlorofluorocarbons (CFCs) in industrial applications such 

as fire extinguishing, foam blowing, and refrigeration. PFCs have essentially zero ozonedestroying capacity and can be considered “ozone-friendly.” However, as pointed out by this 

paper, it is important also to consider the possible role of PFCs as greenhouse gases. 

Ravishankara et al. determined the atmospheric lifetime of six of these gases, a crucial parameter 

used in the calculation of the Global Warming Potential (GWP) index used by policymakers to 

gauge each compound’s global climate impact. The researchers found that these chemical 

species had atmospheric residence times of 2,000 to 50,000 years (many would live longer than 

the past human-civilization time span!) and were up to 12,000 times more potent greenhouse 

gases than carbon dioxide. The implications for policymakers of these newly recognized 

“immortal” greenhouse gases were threefold: (1) emissions of PFCs would accumulate in the 

atmosphere for tens of centuries; (2) the Global Warming Potentials for these compounds would 

be much larger than the CFCs they would replace; and (3) it would take the atmosphere an 

extremely long time to recover from any inputs of these compounds. This paper delivered sound 

science, in a timely manner, in response to a great need in the national and international 

community, and opened up research in this area in the process. By averting the use of what 

would have been very unsuitable substitutes for the CFCs, the paper spared industry a great 

expense while simultaneously protecting the atmosphere from additional burdens of potent 

greenhouse gases. 

Abstract

The atmospheric lifetimes of the fluorinated gases CF4, C2F6, c–C4F8, (CF3) 2c–C4F6, C5F12, 

C6F14, C2F6Cl, C2F4C2, CF3Cl, and SF6 are of concern because of the effects that these long-lived 

compounds acting as greenhouse gases can have on global climate. The possible atmospheric 

loss processes of these gases were assessed by determining the rate coefficients for the reactions 

of these gases with O(1

D), H, and OH and the absorption cross sections at 121.6 nanometers in 

the laboratory and using these data as input to a two-dimensional atmospheric model. The 

lifetimes of all the studied perfluoro compounds are >2000 years, and those of CF3Cl, CF3CF2Cl, 

and CF2ClCF2Cl are >300 years. If released into the atmosphere, these molecules will 

accumulate and their effects will persist for centuries or millennia. 

130
Decrease in the growth rates of atmospheric chlorofluorocarbons 11 

and 12

James W. Elkins, Thayne M. Thompson, James H. Butler, and Bradley D. Hall 

 NOAA Climate Monitoring and Diagnostics Laboratory

Thomas H. Swanson and Scott O. Cummings 

 NOAA Climate Monitoring and Diagnostics Laboratory/CIRES 

Donald A. Fisher and A.G. Raffo 

 Dupont, Inc.

Nature, 364: 780–783, August 26, 1993 

Significance

Atmospheric measurements of CFC-11 and CFC-12 were initiated by CMDL in 1977 at four 

NOAA baseline stations and at four cooperative sites stretching from near the North Pole to the 

South Pole. In 1985 the Antarctic Ozone Hole was discovered and the cause subsequently found 

to be a chemical reaction fueled by CFCs and related halogen compounds that were subsequently 

controlled by the Montreal Protocol. This paper shows that the steady growth rate of CFC-11 and 

CFC-12 in the atmosphere, first established by the CMDL measurements, were beginning to 

decrease. This landmark paper provided proof that international efforts to limit emissions of

ozone depleting substances were effective and provided encouragement that the stratospheric 

ozone hole phenomenon could be controlled. The value of long-term monitoring of atmospheric 

constituents, even when the role they play in atmospheric chemistry is not clearly known, is 

superbly illustrated by the data presented in this paper. 

Abstract

The discovery of the Antarctic ozone hole in 1985 led to international efforts to reduce emissions 

of ozone-destroying chlorofluorocarbons. These efforts culminated in the Montreal Protocol and 

its subsequent amendments, which called for the elimination of CFC production by 1996. Here 

we focus on CFC-11 (CCl3F) and CFC-12 (CCl2F2), which are used for refrigeration, air 

conditioning and the production of aerosols and foams, and which together make up about half of 

the total abundance of stratospheric organic chlorine. We report on a significant recent decrease 

in the atmospheric growth rates of these two species, based on measurements spanning the past

15 years and latitudes ranging from 83EN to 90ES. This is consistent with CFC-producers’ own 

estimates of reduced emissions. If the atmospheric growth rates of these two species continue to 

slow in line with predicted changes in industrial emission, global atmospheric mixing ratios will 

reach a maximum before the turn of the century, and then begin to decline. 

131
Electron beam moiré 

James W. Dally 

 Mechanical Engineering Department, University of Maryland 

David T. Read 

 NIST Materials Reliability Division 

Experimental Mechanics, 33: 270–277, December 1993 

Significance

This paper was one of the first to go to size scales smaller than can be handled with optical

microscopy, to apply scanning electron microscopy as a tool in experimental mechanics. The 

SEM was used both to create a grating on the specimen, and to image changes in the grating as 

the specimen deformed. 

Abstract 

A method of writing very high frequency line and dot patterns, in excess of 10,000 lines/mm, is 

described. This method uses a very small diameter, 10 to 20 nm, beam of electrons to sensitize a 

100-nm thick layer of electron resist. The line and dot patterns are produced by etching the 

sensitized resist. Moiré fringe patterns occur when the line arrays are observed in the scanning 

electron microscope. Moiré fringes with excellent contrast have been produced at magnifications 

as high as 1900x. This capability permits e-beam moiré to be employed in micromechanics. 

Examples of line arrays, dot arrays and moiré fringe patterns on a brass disk and on a tensile 

specimen fabricated from glass-fiber-reinforced plastic are demonstrated to introduce the 

possibilities for micromechanics applications. 

132
Optical fiber geometry: Accurate measurement of cladding diameter 

Matt Young, Paul D. Hale, and Steven E. Mechels 

 NIST Electromagnetic Technology Division 

NIST Journal of Research, 98: 203–216, 1993 

Significance

This paper is the final summary of work on standards for the measurement of the diameter of 

optical fiber and the development of NIST Standard Reference Material 2520. This was one of 

NIST’s most successful programs in support of the optical communications industry. It allowed 

fiber manufacturers to reduce their uncertainties and, for a while, gave American manufacturers 

a competitive advantage over manufacturers from other countries. 

Abstract 

We have developed three instruments for accurate measurement of optical fiber cladding 

diameter: a contact micrometer, a scanning confocal microscope, and a white-light interference 

microscope. Each instrument has an estimated uncertainty (3 standard deviations) of 50 nm or 

less, but the confocal microscope may display a 20 nm systematic error as well. The micrometer 

is used to generate standard Reference Materials that are commercially available. 

133
REFPROP Refrigerant Properties Database: Capabilities, limitations, and 

future directions 

Mark O. McLinden, John G. Gallagher, Marcia L. Huber, and Graham Morrison 

 NIST Thermophysics Division 

Proceedings of the ASHRAE/NIST Refrigerants Conference, Gaithersburg, MD, 1993 

Significance

A potential environmental crisis was identified in the 1970s with the observation that man-made 

chemicals (chlorofluorocarbons or CFCs) used in refrigerators and air conditioners contribute to 

the destruction of the earth’s stratospheric ozone layer. The environmental issues and 

international agreements on the use of refrigeration fluids resulted in a very large effort at NIST 

to consider and study alternative refrigeration working fluids. The REFPROP database, 

described in this paper, was developed to meet the needs of the refrigeration industry in their 

evaluation of alternative refrigerants. The computer program, allowing calculations of properties 

at arbitrary temperatures and pressures, quickly became the de facto standard in the industry, 

permitting a consensus on the numbers to use in the design and evaluation of alternative 

refrigerant systems. The NIST work on refrigerating fluids was able not only to help reduce the 

impact on the ozone layer, but also to generate cooling system designs that use substantially less 

energy than the older technologies. The REFPROP database described here remains a standard, 

and its capabilities have been substantially extended in the years since this paper appeared. The 

models which evolved from the work described here have been incorporated in an ISO standard 

that was adopted in 2004. 

Abstract

The REFPROP computer database has been developed to meet the needs of the refrigeration 

industry in their evaluation of alternative refrigerants. In this paper we highlight the capabilities 

and discuss the limitations of the database through examples of several representative pure 

refrigerants and refrigerant blends. The database employs the Carnahan–Starling–Desantis 

(CSD), modified Bennedict–Webb–Rubin (MBWR), and Haar–Gallagher equations of state for 

thermodynamic properties, and an extended corresponding states (ECS) model for 

thermodynamic and transport properties; the most appropriate model for specific applications is 

recommended. 

134
Surface climate variations over the North Atlantic Ocean during winter: 

1900–89

Clara Deser and Maurice L. Blackmon 

 NOAA/CIRES Climate Diagnostics Center 

Journal of Climate, 6: 1743–1753, September 1993 

Significance

This well-cited paper revealed clear evidence for decadal variability in the North Atlantic Ocean, 

overlying atmosphere and sea ice. One intriguing result, among many, was that ice anomalies in 

the Labrador Sea lead SST anomalies in the North Atlantic by 2 years. Overall, the analyses 

suggested that ice-ocean-atmosphere interaction could result in low-frequency (> 10 years) 

variability in a number of ways and strongly motivated the research community to model and 

explain this variability. 

Abstract

The low-frequency variability of the surface climate over the North Atlantic during winter is 

described, using 90 years of weather observations from the Comprehensive Ocean-Atmosphere 

Data Set. Results are based on empirical orthogonal function analysis of four components of the 

climate system: sea surface temperature (SST), air temperature, wind, and sea level pressure. An 

important mode of variability of the wintertime surface climate over the North Atlantic during 

this century is characterized by a dipole pattern in SSTs and surface air temperatures, with 

anomalies of one sign east of Newfoundland, and anomalies of the opposite polarity off the 

southeast coast of the United States. Wind fluctuations occur locally over the regions of large 

surface temperature anomalies, with stronger-than-normal winds overlying cooler-than-normal 

SSTs. This mode exhibits variability on quasi-decadal and biennial time scales. The decadal 

fluctuations are irregular in length, averaging ~9 years before 1945 and ~12 years afterward. 

There does not appear to be any difference between the wind-SST relationships on the different 

time scales. The decadal fluctuations in SSTs east of Newfoundland are closely linked to decadal 

variations in sea ice in the Labrador Sea, with periods of greater than normal sea ice extent 

preceding by ~2 years periods of colder-than-normal SSTs east of Newfoundland. 

Another dominant mode of variability is associated with the global surface warming trend during

the 1920s and 1930s. The patterns of SST and air temperature change between 1900–29 and 

1939–68 indicate that the warming was concentrated along the Gulf Stream east of Cape 

Hatteras. Warming also occurred over the Greenland Sea and the eastern subtropical Atlantic. 

The warming trend was accompanied by a decrease in the strength of the basin-scale atmospheric 

circulation (negative phase of the North Atlantic Oscillation). In marked contrast to the dipole 

pattern, the wind changes occurred downstream of the largest SST anomalies; hence, the gradual 

surface warming along the Gulf Stream may have been a result of altered ocean currents rather 

than local wind forcing.

135
Welding for cryogenic service 

Thomas A. Siewert and Chris N. McCowan 

 NIST Materials Reliability Division 

Chapter in ASM Handbook: Volume 6 (Welding), Materials Park, Ohio: ASM International, 

1016–1019, 1993 

Significance

This book chapter summarizes about 20 years of research at NIST on the effect of welding on the 

behavior of fabricated structures at cryogenic temperatures. The behavior of the welds is similar 

to that of the plate material in many ways, yet there are some important differences and some

special considerations. Therefore, this data complements the other reports on plates and sheets, 

and serves to guide fabricators and welding engineers on the key joining issues. This report 

covers the factors that determine the strength and toughness of the welds at temperatures down to 

4 K, and includes tables to illustrate the trends. It includes some comments on other important 

properties such as fatigue strength, and coefficient of thermal expansion (which becomes 

particularly important when dissimilar filler metals are chosen). It also discusses the powerful 

effect on toughness of inclusions (predominately oxides) in the weld pool. This book chapter was 

one of our last publications in this area and so serves as a summary of our final understanding of 

the most important factors. 

Abstract 

Cryogenic temperatures cause many structural alloys to become brittle, which is an unacceptable 

condition in most structural applications. Therefore, structures built for service at low 

temperatures are typically made from alloys that maintain some ductility at the service 

temperatures. Cryogenic alloys include 9Ni steels, austenitic stainless steels, manganese stainless 

steels, maraging steels, titanium, aluminum, and nickel alloys. The choice of weld-metal alloy 

may depend solely on the strength of the alloy at a given temperature or on a combination of 

strength, toughness, fatigue resistance, thermal conductivity, magnetic permeability, and other 

considerations. 

Wrought or cast alloy structural members are usually joined using filler materials with 

compositions that are similar, but not identical, to the parent material. The weld composition is 

optimized to compensate for the inherent differences in the properties of weld and parent 

material that are due to grain structure, inclusion content, and cooling rate differences. The goal 

is to match, as closely as possible, the mechanical and physical properties of the weld and parent 

material. When nonmatching weld compositions are most appropriate, differences between the 

welds and parent material in terms of thermal contraction, corrosion, and other factors must be 

considered. This article discusses these differences and explains how they affect the choice of the 

weld filler metal. 

136
Metrological accuracy of the electron pump 

John M. Martinis and Michael Nahum 

 NIST Electromagnetic Technology Division 

Physical Review Letters, 72: 904–907, 1994 

Significance

The charge of an electron is so small that the current in an ordinary flashlight bulb amounts to 

more than 10,000,000,000,000,000,000 electrons passing through every second. How can you 

get a hold of just one? That requires a tricky bit of engineering, including a circuit so small it 

must be fabricated using an electron microscope and temperatures so cold that absolute zero is 

only a fraction of a degree colder. However, as John Martinis and Michael Nahum demonstrated 

in 1994, with such apparatus, you can not only manipulate electrons one by one, but count them

with an accuracy of 0.5 parts per million. This pioneering work opened the possibility of making 

new fundamental standards for both electrical current and capacitance. 

Abstract

We have operated a five-junction electron pump with an error for transferring electrons of 

approximately 0.5 part per 106

. The error predicted from existing theory is several orders of 

magnitude smaller, thus implying that our present understanding of the Coulomb blockade is 

incomplete. We conjecture that the errors arise from photon-assisted tunneling, where the photon 

energy is supplied by noise from the environment. 

137
Response of the thermosphere and ionosphere to geomagnetic storms

Tim J. Fuller-Rowell and Mihail V. Codrescu 

 NOAA Space Environment Laboratory/CIRES 

R.J. Moffett and Shaun Quegan 

 University of Sheffield 

Journal of Geophysical Research, 99: 3893–3914, 1994 

Significance

The ionosphere during geomagnetic storms exhibits complicated and apparently inexplicable 

behavior often described as chaotic. This paper recognized the interplay between the instant a 

magnetic storm begins and the subsequent behavior of the ionosphere above an arbitrary 

location. Through the use of a sophisticated model, the work demonstrated that the apparent 

chaotic behavior could be explained and predicted in detail using a minimum of physical 

assumptions. In doing so, a complex physical problem, often thought intractable, was resolved. 

This paper described the balance of physical processes responsible for the ionospheric response 

to geomagnetic storms. In particular, Fuller-Rowell et al. were able to show the dependence on 

Universal Time, and explain the origin of the local time modulation in the positive and negative 

phases. Previously the storm-time response was regarded as chaotic, with positive and negative 

phases appearing randomly. The paper provides a framework for analysis of the observed 

ionospheric response to geomagnetic storms. In addition to separating local time from 

UT/longitude dependence, the paper provided an explanation of that part of the response that is 

consistent from one storm to the next. The physical insight enabled an empirical storm-time

prediction model to be developed for the International Reference Ionosphere, something that was 

not possible before. While a relatively recent publication, this paper has been cited 120 times 

since publication with 86 “significances” since 1998 attesting to the growing recognition of its 

importance. 

Abstract

Four numerical simulations have been performed, at equinox, using a coupled thermosphereionosphere model to illustrate the response of the upper atmosphere to geomagnetic storms. The 

storms are characterized by an increase in magnetospheric energy input at high latitude for a 12-

hour period; each storm commences at a different universal time (UT). The initial response at 

high latitude is that Joule heating raises the temperature of the upper atmosphere and ion drag 

drives high-velocity neutral winds. The heat source drives a global wind surge, from both polar 

regions, which propagates to low latitudes and into the opposite hemisphere. The surge has the 

character of a large-scale gravity wave with a phase speed of about 600 m s-1. Behind the surge a 

global circulation of magnitude 100 m s-1 is established at middle latitudes, indicating that the 

wave and the onset of global circulation are manifestations of the same phenomena. A dominant 

feature of the response is the penetration of the surge into the opposite hemisphere where it 

138
drives poleward winds for a few hours. The global wind surge has a preference for the night 

sector and for the longitude of the magnetic pole and therefore depends on the UT start time of 

the storm. A second phase of the meridional circulation develops after the wave interaction but is 

also restricted, in this case by the buildup of zonal winds via the Coriolis interaction. 

Conservation of angular momentum may limit the buildup of zonal wind in extreme cases. The 

divergent wind field drives upwelling and composition change on both height and pressure 

surfaces. The composition bulge responds to both the background and the storm-induced 

horizontal winds; it does not simply rotate with Earth. During the storm the disturbance wind 

modulates the location of the bulge; during the recovery the background winds induce a diurnal 

variation in its position. Equatorward winds in sunlight produce positive ionospheric changes 

during the main driving phase of the storm. Negative ionospheric phases are caused by increases 

of molecular nitrogen in regions of sunlight, the strength of which depends on longitude and the 

local time of the sector during storm input. Regions of positive phase in the ionosphere persist in 

the recovery period due to decreases in mean molecular mass in regions of previous 

downwelling. Ion density changes, expressed as a ratio of disturbed to quiet values, exhibit a 

diurnal variation that is driven by the location of the composition bulge; this variation explains 

the ac component of the local time variation of the observed storm phase. 

139
A mechanism for the recurrence of wintertime midlatitude SST anomalies 

during winter

Michael A. Alexander and Clara Deser 

 NOAA Climate Monitoring and Diagnostics Laboratory/CIRES 

Journal of Physical Oceanography, 25: 122–137, 1995 

Significance

This paper was the first to clearly demonstrate that temperature anomalies that form at the 

surface and extend downward into the deep ocean mixed layer in winter, could remain intact in 

the seasonal thermocline during the following summer, and then reappear at the surface when the 

mixed layer again deepened in the following fall/winter. This process, termed the “reemergence 

mechanism,” was confirmed using both subsurface temperature data and mixed layer model 

simulations. The reemergence mechanism provides an avenue to predict sea surface temperature 

anomalies and their potential impact on the atmospheric circulation. 

Abstract

In the early 1970s, Namias and Born speculated that ocean temperature anomalies created over 

the deep mixed layer in winter could be preserved in the summer thermocline and reappear at the 

surface in the following fall or winter. This hypothesis is examined using upper-ocean 

temperature observations and simulations with a mixed layer model. The data were collected at 

six ocean weather stations in the North Atlantic and North Pacific. Concurrent and lead-lag 

correlations are used to investigate temperature variations associated with the seasonal cycle in 

both the observations and the model simulations. 

Concurrent correlations between the surface and subsurface temperature anomalies in both the 

data and the model indicate that the penetration of temperature anomalies into the ocean is 

closely tied to the seasonal cycle in mixed layer depth: high correlations extend to relatively deep 

(shallow) depths in winter (summer). Lead-lag correlations in both the data and the model, at 

some of the stations, indicate that temperature anomalies beneath the mixed layer in summer are 

associated with the temperature anomalies in the mixed layer in the previous winter/spring and 

following fall/winter but are unrelated or weakly opposed to the temperature anomalies in the 

mixed layer in summer. These results suggest that vertical mixing processes allow ocean 

temperature anomalies created over a deep mixed layer in winter to be preserved below the 

surface in summer and reappear at the surface in the following fall, confirming the Namias–Born 

hypothesis. 

140
Analog-to-digital converters and their applications in radio receivers 

Jeffery A. Wepman 

 NTIA Institute for Telecommunication Sciences 

IEEE Communications Magazine, 39–45, May 1995 

Significance

This article provides a foundation for understanding analog-to-digital converters in software 

defined radio (SDR) receiver applications. It is based on pioneering research on SDR’s 

conducted at ITS. An SDR is a radio consisting of: (a) a receiver where the received signal is 

digitized and then processed using software-programmable digital signal processing techniques, 

and/or (b) a transmitter where the modulated signal to be transmitted is generated as a digital 

signal using software-programmable digital signal processing techniques; the digital signal is 

then converted to an analog signal for transmission. The software programmability of an SDR 

allows easy changes of the radio’s fundamental characteristics such as modulation type, 

operating frequency, and bandwidth. 

The two essential components in an SDR receiver are analog-to-digital converters and digital 

signal processing hardware. This article offers an extremely clear, comprehensive, and yet 

concise discussion of both the theoretical and practical aspects of analog-to-digital converters for 

radio receiver applications, including sampling methods, effects of quantization noise, and 

important specifications such as signal-to-noise ratio, spurious-free dynamic range, and noise 

power ratio. Over the past ten years, development of SDR’s has increased dramatically and 

continues to gain momentum. SDR technology has already been used in cellular and PCS base 

stations as well as fixed-station military radios. Future proliferation of SDR’s is anticipated as 

the migration from traditional radio to SDR technology in handheld devices such as cellular 

telephones and portable public safety and military radios is realized. 

Abstract 

Rapid advances in hardware development of analog-to-digital converters (ADCs) have paved the 

way for development of radio receivers using digitization at the IF, and in some cases, at the RF. 

The constraints placed on these receivers due to hardware limitations of these devices are 

discussed and some examples of high-speed, state-of-the-art ADCs are given. 

141
Demonstration of a fundamental universal quantum logic gate 

Chris Monroe, Dawn M. Meekhof, Brian E. King, Wayne M. Itano, and David J. Wineland 

 NIST Time and Frequency Division 

Physical Review Letters, 75: 4714–4717, 1995 

Significance

This paper reported the world’s first experimental demonstration that the quantum mechanical 

properties of atoms could be used to perform simple logic operations, a crucial first step toward 

building a quantum computer. Quantum computing is one of the most exciting areas of research 

today, with the potential to transform information technology and our understanding of the 

microscopic world. 

This work built on the mastery of Dave Wineland’s group in using laser cooling and trapping and 

exquisite manipulation of individual ions (charged atoms) first demonstrated in Wineland et al., 

1978 (this volume). Quantum computing seeks to use the unique properties of quantum 

mechanics to develop systems based on a small number of quantum bits (qubits) such as ions, 

atoms, or nanoscale devices that will be able to perform certain kinds of very important 

calculations many orders of magnitude faster than today’s best electronic (classical) computers. 

Quantum information is one of the most exciting and demanding fields in physics and 

information sciences today, attracting many of the world’s top scientists and mathematicians. 

Essentially, it promises to make possible calculations that are now impossible and to introduce a 

type of computation that is more different from modern electronic computers than those 

computers are from the abacus. Wineland helped launch the field of experimental quantum

computing and continues to be a world leader. This paper reports the demonstration of a 

“controlled-NOT” quantum logic gate, which in conjunction with simple single-bit operations, 

forms a universal quantum logic gate for quantum computation. 

Abstract 

We demonstrate the operation of a two-bit “controlled-NOT” quantum logic gate, which, in 

conjunction with simple single-bit operations, forms a universal quantum logic gate for quantum

computation. The two quantum bits are stored in the internal and external degrees of freedom of

a single trapped atom, which is first laser cooled to the zero-point energy. Decoherence effects 

are identified for the operation, and the possibility of extending the system to more qubits 

appears promising. 

142
The optimal growth of tropical sea surface temperature anomalies

Cécile Penland and Prashant D. Sardeshmukh 

 NOAA Climate Monitoring and Diagnostics Laboratory/CIRES 

Journal of Climate, 8: 1999–2024, 1995 

Significance

Prior to this paper, ENSO events were thought to arise from the instability of coupled air-sea 

interactions in the tropical Indo-Pacific basin. This paper presented strong evidence that the 

coupled interactions were in fact stable and governed by linear, randomly perturbed dynamics. 

An El Niño or La Niña event was argued to arise from the random significance of an “optimal” 

initial structure that would then amplify linearly into a full-blown event before fading away. This 

view of ENSO has gradually become widely accepted, and has proven invaluable in the 

development of models of ENSO prediction. 

Abstract

It is argued from SST observations for the period 1950–90 that the tropical Indo-Pacific oceanatmosphere system may be described as a stable linear dynamical system driven by spatially 

coherent Gaussian white noise. Evidence is presented that the predictable component of SST 

anomaly growth is associated with the constructive interference of several damped normal modes 

after an optimal initial structure is set up by the white noise forcing. In particular, El NiñoSouthern Oscillation (ENSO) growth is associated with an interplay of at least three damped 

normal modes, with periods longer than two years and decay times of 4 to 8 months, rather than 

the manifestation of a single unstable mode whose growth is arrested by nonlinearities. 

Interestingly, the relevant modes are not the three least damped modes of the system. Rather, 

mode selection, and the establishment of the optimal initial structure from which growth occurs, 

are controlled by the stochastic forcing. Experiments conducted with an empirical stochasticdynamical model show that stochastic forcing not only adds energy to the system, but also plays 

a role in setting up the optimal structure. 

It is shown that growth from modal interference can occur for as long as 18 months, which 

within the confines of this model defines a predictability limit for growth events. Growth 

associated with the stochastic forcing is also possible, but is unpredictable. The timescale on 

which the predictable and unpredictable components of SST growth become comparable to each 

other gives a more conservative predictability limit of 15 months. 

The above scenario is based on empirical evidence obtained from SST anomalies alone. From

the results of several tests based on statistical properties of linear and nonlinear dynamical 

systems, one may conclude that much of the ENSO cycle in nature is dominated by stable, forced 

dynamics. 

143
A “Schrödinger cat” superposition state of an atom 

Chris Monroe, Dawn M. Meekhof, Brian E. King, and David J. Wineland 

 NIST Time and Frequency Division 

Science, 272: 1131–1136, May 24, 1996 

Significance

Dave Wineland’s ability to exquisitely control ions with laser light and electromagnetic fields 

has resulted in many of the first key tests of the unique properties of quantum mechanics. For 

example, Wineland’s group was the first in the world to demonstrate a so-called “Schrödinger 

cat” state. Erwin Schrödinger, a pioneering quantum theorist, illustrated the strangeness of the 

quantum principle of superposition through the fanciful description in the 1930s of a cat in a 

closed box that is simultaneously in a state of being dead and alive until an observer opens the 

box to discover the condition of the cat. In 1996, Wineland conducted the first direct observation 

of superposition by showing that a single ion simultaneously existed in two states separated by 

some 80 nm (much larger than the approximate 0.1 nm size of the ion) until forced by the 

measurement process to collapse into one of the states. 

Abstract 

A “Schrödinger cat”-like state of matter was generated at the single atom level. A trapped 9

Be+

ion was laser-cooled to the zero-point energy and then prepared in a superposition of spatially 

separated coherent harmonic oscillator states. This state was created by application of a sequence 

of laser pulses, which entangles internal (electronic) and external (motional) states of the ion. 

The Schrödinger cat superposition was verified by detection of the quantum mechanical 

interference between the localized wave packets. This mesoscopic system may provide insight 

into the fuzzy boundary between the classical and quantum worlds by allowing controlled studies 

of quantum measurement and quantum decoherence. 

144
Solidification sensing using high-energy x-ray diffraction 

Thomas A. Siewert, William P. Dubé, and Dale W. Fitting 

 NIST Materials Reliability Division 

Advanced Materials and Processes, 23–25, July 1996 

Significance

Most x-ray diffraction measurements are performed with conventional low-energy tubes, which 

limit the depth of penetration to a few micrometers in most materials. As a part of the work 

under the NIST Aerospace Consortium, we developed high-energy x-ray diffraction procedures 

(using energies up to 320 kVp), which penetrate over 20 mm of aluminum, and so permit x-ray 

transmission studies. This report summarizes a number of our tests. One of the most interesting 

was a series of diffraction patterns for a high-purity aluminum rod as it melted and then 

resolidified. The x-rays were sufficiently energetic to not only penetrate about 10 mm of 

aluminum, but also the crucible and furnace walls. Thus, this was the only technique that was 

found to penetrate the wall and furnace elements of a high-temperature vacuum furnace, and so 

permit monitoring of the solidification front location and shape during the solidification of

single-crystal nickel-alloy turbine blades. The series of patterns in this publication shows a 

reduction in the number of diffraction spots as the grain structure coarsened during heating, a 

total loss of spots (and formation of a diffuse diffraction ring) as the aluminum melted, and the 

reappearance of new spots as the aluminum resolidified. This research served as the basis for 

U.S. Patent 5,589,690 and was reported in more detail in NIST TN 1500-3. 

Abstract 

A high-energy transmission x-ray diffraction technique that combines the capabilities of

conventional high- and low-energy x-ray systems has been developed at the National Institute of 

Standards and Technology as a noncontact sensor for locating the liquid/solid boundary in metal 

castings. The high-energy (160–320 kV) x-rays can penetrate the thickness of most castings, and 

the mold and furnace walls. One practical goal for this new method is to collect data on the 

position, velocity, and possibly the shape of the solidification front of directionally solidified 

castings. Such information is vital for development and verification of improved solidification 

models, but it has been difficult to gather because of high temperatures, strong magnetic fields, 

and vacuum casting furnaces. 

145
X-ray detection using a superconducting transition-edge sensor 

microcalorimeter with electrothermal feedback 

Kent D. Irwin, Gene C. Hilton, David A. Wollman, and John M. Martinis 

 NIST Electromagnetic Technology Division 

Applied Physics Letters, 69(13): 1945–1947, 1996 

Significance

This paper describes the first practical realization of a new kind of high performance x-ray 

detector. The transition-edge sensor (TES) microcalorimeter measures x-ray energy thermally, 

with the absorbed x-ray photon causing a small but measurable temperature increase of the 

detector. By utilizing a highly sensitive superconducting phase transition as the thermometer, and 

by operating at low temperatures, this type of detector provides a high resolution measurement of 

the x-ray energy. The real significance of this paper lies in the new capabilities this type of

detector permits. Since this publication, x-ray detectors have been developed using this technique 

with energy resolution more than 40 times better than conventional instruments. Commercial 

products based on these devices are now being developed for materials analysis applications, and 

many groups throughout the world are developing systems based on this technology for nextgeneration x-ray and infrared astronomical instruments. 

Abstract 

We have developed a new type of x-ray detector based on a superconducting transition-edge 

thermometer operated near 100 mK. A superconducting quantum interference device is used to 

measure the current through the thermometer, and negative electrothermal feedback is used to 

improve the energy resolution and shorten the thermal time constant. We have used a detector 

mounted on a scanning electron microscope to measure the energy of titanium Kα (4.5 keV) 

fluorescence x rays with a resolution better than 14 eV full width at half-maximum. Using two 

other devices, we have measured an energy resolution for Joule heat pulses of 2.6 eV at 1 keV 

and 0.2 eV at 4 eV, the best reported for any calorimeter. An electrical noise equivalent power of 

3 × 10-18

 W/√Hz was also measured, suggesting the use of these detectors as infrared bolometers. 

146
Arctic environmental change of the last four centuries 

Jonathan T. Overpeck 

 NOAA Paleoclimatology Program, NCDC 

Konrad Hughen 

 Institute of Arctic and Alpine Research, 

 University of Colorado 

Douglas Hardy and Raymond Bradley 

 University of Massachusetts 

Roslyn Case 

 University of California at Los Angeles 

Maryanne Douglas 

 University of Toronto, Canada 

Bruce Finney 

 Institute of Marine Sciences 

 University of Alaska 

Konrad Gajewski 

 University of Ottawa, Canada 

Gordon Jacoby 

 Lamont-Doherty Earth Observatory 

 Columbia University 

Anne Jennings 

 Institute of Arctic and Alpine Research 

University of Colorado 

Scott Lamoureux 

 University of Alberta, Canada 

Andrew Lasca 

 Bates College 

Glen MacDonald 

 University of California at Los Angeles 

Jay Moore 

 Institute of Arctic and Alpine Research 

 University of Colorado 

Michael Retelle 

 Bates College 

Sheldon Smith 

 University of Massachusetts 

Alex Wolfe 

 Institute of Arctic and Alpine Research 

 University of Colorado 

Gregory Zielinski 

 University of New Hampshire

Science, 278: 1251–1256, November 14, 1997 

Significance

This paper is among a set of recently published, widely cited papers that document the preinstrumental record of temperature and which have been used to place 20th century warming into 

a long-term context. A large international team of scientists combined the results of their 

research to generate the first circum-Arctic view of surface air temperature changes over the last

400 years. The study used proxy climate data from tree-rings, ice-cores, lake and marine 

sediments. This “multi-proxy” approach insures that results were not biased as is possible if only 

one proxy source was used. Together, these proxy data allow 20th century warming to be 

evaluated in the context of the past 400 years. They indicate that the Arctic has warmed up to 

1.5 °C since 1850—the coolest interval of the Arctic “Little Ice Age.” Much of the recent Arctic 

warming took place between 1850 and 1920, most likely due to natural processes, whereas the 

warming after 1920 is increasingly difficult to ascribe to natural forcing. The Overpeck et al. 

results confirm results of earlier regional studies that suggest the Arctic warming is 

unprecedented in the past four centuries. The authors also discuss the impacts of warming across 

the Arctic, a region particularly sensitive to warming. These impacts include glacial melting, 

permafrost warming, lake and forest ecology changes, and the retreating of sea-ice. 

147
Abstract 

A compilation of paleoclimate records from lake sediments, trees, glaciers, and marine sediments 

provides a view of circum-Arctic environmental variability over the last 400 years. From 1840 to

the mid-20th century, the Arctic warmed to the highest temperatures in four centuries. This 

warming ended the Little Ice Age in the Arctic and has caused retreats of glaciers, melting of 

permafrost and sea ice, and alteration of terrestrial and lake ecosystems. Although warming, 

particularly after 1920, was likely caused by increases in atmospheric trace gases, the initiation 

of the arming in the mid-19th century suggests that increases solar irradiance, decreased volcanic 

activity, and feedbacks internal to the climate system played roles. 

148
El Niño, La Niña, and the nonlinearity of their teleconnections 

Martin P. Hoerling 

 NOAA/CIRES Climate Diagnostics Center 

Arun Kumar 

 NOAA National Center for Environmental Prediction 

Min Zhong 

 NOAA/CIRES Climate Diagnostics Center

Journal of Climate, 10(10): 1769–1786, 1997 

Significance

This heavily cited paper showed that the paradigm of “equal and opposite” atmospheric 

responses to El Niño and La Niña conditions was fundamentally incorrect. It provided an 

explanation for the different characteristics of the responses to El Niño and La Niña forcings 

over the North American region. As such, this paper paved the way for significant improvements 

in NOAA forecasts of the climate response to El Niño and La Niña. 

Abstract

The paradigm of an atmospheric system varying linearly with respect to extreme phases of the El 

Niño–Southern Oscillation is questioned. It is argued that the global response to tropical Pacific 

sea surface temperature forcing will be inherently nonlinear. A physical basis for this intrinsic 

nonlinearity is the thermodynamic control on deep convection. 

Climate statistics for warm and cold events of the tropical Pacific are analyzed separately for the 

northern winter periods during 1950–96. Composite analysis of 500-mb heights reveal planetaryscale teleconnection patterns, as noted in earlier studies. A new result is the evidence for an 

appreciable 35E longitude phase shift between the warm and cold event circulation composites, 

and the two wave trains appear to have different tropical origins. A large nonlinear component in 

North American surface climate anomalies is also found, which is consistent with such a phase 

shift in teleconnections. In the Tropics, rainfall anomalies also show evidence of nonlinear 

behavior. The maximum rain anomalies along the equator are located east of the date line during 

warm events, but west of the date line during cold events. The interpretation of this behavior is 

complicated, however, by the fact that composite warm event SST anomalies are not the exact 

inverse of their cold event counterparts. 

Idealized atmospheric general circulation model (AGCM) experiments are performed in order to 

test the question of whether the observed nonlinearity is an intrinsic property of the atmospheric 

system. The model is forced with a composite SST anomaly that undergoes a realistic seasonally 

varying ENSO life cycle, as described by E. Rasmusson and T. Carpenter. Both positive and 

negative phases of the SST anomaly are used, and a 40-member ensemble of warm and cold 

event model simulations is conducted. A nonlinear climate response in the AGCM is found that 

closely resembles the observed composites, including a shift in the equatorial positions of the 

maximum rain responses and a phase shift of teleconnection patterns in the upper troposphere. 

149
Barotropic model experiments indicate that the inherent nonlinearity in the tropical rain response 

may itself be responsible for the phase shift in the extratropical teleconnection patterns. 

150
Isochoric ( p, ρ, T) measurements for five natural gas mixtures from 

T = (225 to 350) K at pressures to 35 MPa 

Joseph W. Magee, William M. Haynes, and Michael J. Hiza

 NIST Physical and Chemical Properties Division 

Journal of Chemical Thermodynamics, 29: 1439–1454, 1997 

Significance

Experimental measurements on natural gas properties are necessary to establish the wide ranging 

and flexible models used to describe these high-energy-content fluids. The program at NIST was 

geared to establishing a validated set of measurements on key mixtures with density determined 

at an expanded uncertainty of 0.05 %. The techniques used, mainly an isochoric gas expansion 

method on gravimetrically prepared mixtures, had been well established at NIST. The 

measurements described in this paper form the basis for the models used in our 100 billion dollar 

natural gas industry. 

Abstract

Measurements of the (p, ρ, T) properties of five natural gas mixtures were carried out at 

temperatures from (225 to 350) K at pressures to 35 MPa using an isochoric gas expansion 

apparatus. Ten isochores have been determined for each mixture at densities ranging from 1 mol 

· dm-3 to 16 mol · dm-3. The gas samples were prepared gravimetrically from pure gases of 

verified research-grade purity. The uncertainty of the density measurements arises primarily 

from uncertainties involved in the determination of the experimental cell volume and of the 

amount of substance contained in the experimental volume. When all components of 

experimental uncertainty arising from random effects are considered, the expanded uncertainty 

(comprising 95 per cent confidence interval) of the density measurements is estimated to be 

0.044 per cent. 

151
Mapping city lights with nighttime data from the DMSP Operational 

Linescan System

Christopher D. Elvidge 

 NOAA National Geophysical Data Center 

Kimberly E. Baugh 

 NOAA/CIRES 

Eric A. Kihn and Herbert W. Kroehl 

 NOAA National Geophysical Data Center 

Ethan R. Davis 

 NOAA/CIRES 

Photogrammetric Engineering and Remote Sensing, 63(6), 727–734, 1997 

Significance

This paper received the outstanding paper of the year award issued by the Royal Society. It 

defines the method used to detect stable and ephemeral sources of “nighttime lights” from

imagery designed to detect clouds. The methodology has been used to estimate the population of 

countries, the economic vitality of regions, increases in urban sprawl, and local amounts of 

carbon emissions. 

Abstract

The Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) has 

a unique capability to detect low levels of visible and near-infrared (NVIR) radiance at night. 

With the OLS “VIS” band data, it is possible to detect clouds illuminated by moonlight, plus 

lights from cities, towns, industrial sites, gas flares, and ephemeral events such as fires and 

lightning illuminated clouds. This paper presents methods which have been developed for 

detecting and geolocating VNIR emission sources with nighttime DMSP-OLS data and the 

analysis of image time series to identify spatially stable emissions from cities, towns and 

industrial sites. Results are presented for the United States. 

152
Electromagnetic theory of reverberation chambers 

David A. Hill 

 NIST Radio-Frequency Technology Division 

NIST Technical Note 1506, 1998 

Significance

Reverberation chambers have become very popular worldwide for EMC immunity and emissions 

measurements. This Tech Note provides the necessary theory for performing such 

measurements. It is the only publication that simultaneously provides both electromagnetic and 

statistical theory for predicting field properties and test object responses. Hence, it has been 

heavily used and referenced worldwide. The U.S. Air Force has adopted it as its standard 

reference document for reverberation chamber measurements in house and by contractors. 

Abstract 

This report presents the electromagnetic theory of reverberation chambers as applied to 

electromagnetic compatibility measurements. For radiated immunity measurements, mode theory 

and the plane-wave integral representation are useful in determining electric and magnetic field 

characteristics and chamber quality factor (Q). The plane-wave integral representation also 

provides a convenient method for describing the response of a reference antenna or a test object 

in a stirred field. For radiated emissions, energy conservation or electromagnetic reciprocity can 

be used to describe the measurement of total radiated power. Comparisons of theory and 

measurements are presented for chamber Q, probability density functions of fields and received 

power, and radiated immunity and emissions of a simple test object. Recommendations are made 

for improvements in statistical electromagnetic theory as applied to mechanical stirring and the 

statistics of immunity and emissions measurements. 

153
2000 years of drought variability in the central United States 

Connie A. Woodhouse and Jonathan T. Overpeck 

 NOAA National Climatic Data Center, Paleoclimatology Program

Bulletin of the American Meteorological Society, 79: 2693–2714, 1998 

Significance 

Our understanding of drought is based on the 20th century records of climate, which contain only 

a subset of the range of climatic variability that can be expected under naturally occurring 

climate conditions. This paper assessed the results of several studies documenting drought in the 

central and western United States over the past 2000 years, based on a wide range of 

paleoclimatic data. These studies indicated that the severity of droughts of the 20th century was 

eclipsed several times by droughts in the previous 2000 years. Of particular note is a remarkably 

widespread and persistent “megadrought” at the end of the 16th century. If the climate of the past 

can be considered a guide to what may be expected in the future, this work suggests that 

droughts more severe than those of the 1930s and 1950s are likely to occur in the future, a 

likelihood that might be exacerbated by greenhouse warming. These results have important

implications for water resource management, particularly in the arid and semi-arid regions of the 

United States. 

Abstract 

Droughts are one of the most devastating natural hazards faced by the United States today. 

Severe droughts of the twentieth century have had large impacts on economies, society, and the 

environment, especially in the Great Plains. However, the instrumental record of the last 100 

years contains only a limited subset of drought realizations. One must turn to the paleoclimatic 

record to examine the full range of past drought variability, including the range of magnitude and 

duration, and thus gain the improved understanding needed for society to anticipate and plan for 

droughts of the future. Historical documents, tree rings, archaeological remains, lake sediment, 

and geomorphic data make it clear that the droughts of the twentieth century, including those of

the 1930s and 1950s, were eclipsed several times by droughts earlier in the last 2000 years, and 

as recently as the late sixteenth century. In general, some droughts prior to 1600 appear to be 

characterized by longer duration (i.e., multidecadal) and greater spatial extent than those of the 

twentieth century. The authors’ assessment of the full range of past natural drought variability, 

deduced from a comprehensive review of the paleoclimatic literature, suggests that droughts 

more severe than those of the 1930s and 1950s are likely to occur in the future, a likelihood that 

might be exacerbated by greenhouse warming in the next century. Persistence conditions that 

lead to decadal-scale drought may be related to low-frequency variations, or base-state shifts, in 

both the Pacific and Atlantic Oceans, although more research is needed to understand the 

mechanisms of severe drought. 

154
A capacitance standard based on counting electrons 

Mark W. Keller, Ali L. Eichenberger, John M. Martinis, and Neil M. Zimmerman 

 NIST Electromagnetic Technology Division 

Science, 285: 1706–1709, 1999 

Significance

Once precise electron counting was demonstrated in 1994, the question became whether or not it 

could be put to practical use. Five years later, Mark Keller, Ali Eichenberger, John Martinis, and 

Neil Zimmerman proved the case by building a fully practical standard for the measurement of 

electrical capacitance. Their measurement technique required pumping an exact number of 

electrons onto a capacitor, around 50 million, then accurately measuring the capacitor’s voltage 

without disturbing more than a few electrons. Their new technique is accurate to better than 0.3 

parts per million and will provide an important check on established methods of capacitance 

calibration. It will also yield an independent measure of the fine structure constant, one of

nature’s fundamental numbers. 

Abstract 

A capacitance standard based directly on the definition of capacitance was built. Single-electron 

tunneling devices were used to place N electrons of charge e onto a cryogenic capacitor C, and 

the resulting voltage change ∆V was measured. Repeated measurements of C = Ne/∆V with this 

method have a relative standard deviation of 0.3 × 10-6. This standard offers a natural basis for 

capacitance analogous to the Josephson effect for voltage and the quantum Hall effect for 

resistance. 

155
For 100 years, notched bar impact testing standards have yielded widespread 

benefits for industry 

Michael P. Manahan, Chris N. McCowan, Thomas A. Siewert, John M. Holt, Francis J. Marsh, 

and Earl A. Ruth 

 NIST Materials Reliability Division 

Standardization News, 27(2): 30–35, February 1999 

Significance

This paper was written to recognize the centenary of the pendulum impact test, now most 

commonly used in a configuration known as the Charpy impact test. The paper described the 

early history of the test, the development of standard methods that reduce the uncertainty in the 

measurements, and the importance of the technique in the steel fabrication industries (including 

many fracture critical structures such as bridges, ships, and buildings). This paper received an 

award from the American Society for Testing and Materials during their centennial celebration in

1998, in recognition of the importance of impact standards in promoting public safety and 

reducing the costs associated with material variation. 

Abstract 

Without standardization, the impact test has little meaning. The test result obtained from an 

impact test is dependent upon the specimen size, notch geometry, and the geometry of the anvils 

and striker. To a lesser degree, impact test results are also dependent upon other variables such as 

impact velocity, energy lost to the test machine, and friction. The goal of those who have written 

and modified ASTM E23, Standard Test Methods for Notched Bar Impact Testing of Metallic 

Materials, has been, and is to standardize and control the variables associated with impact 

testing. 

156
Objective estimation of perceived speech quality 

Part I: Development of the measuring normalizing block technique 

Part II: Evaluation of the measuring normalizing block technique 

Stephen Voran 

 NTIA Institute for Telecommunication Sciences 

IEEE Transactions on Speech and Audio Processing, 7(4): 371–382 and 383–390, July 1999 

Significance

This set of two papers presents a substantial innovation and practical advancement in the 

objective estimation of transmitted speech quality. The first paper defines the mathematical

approach, which comprises a simple but effective perceptual transformation and a hierarchy of 

measuring normalizing blocks, each of which integrates two perceptually transformed signals 

over a defined time or frequency interval to obtain an objective difference measure that can be 

correlated with subjective (human listener) speech quality evaluations. The second paper 

thoroughly evaluates the resulting new estimators as well as other established metrics. The 

defined estimators have been standardized, patented, licensed, and implemented in commercial 

test equipment. 

Abstract, Part I 

Perceived speech quality is most directly measured by subjective listening tests. These tests are 

often slow and expensive, and numerous attempts have been made to supplement them with 

objective estimators of perceived speech quality. These attempts have found limited success, 

primarily in analog and higher-rate, error-free digital environments where speech waveforms are 

preserved or nearly preserved. The objective estimation of the perceived quality of highly 

compressed digital speech, possibly with bit errors or frame erasures has remained an open 

question. We report our findings regarding two essential components of objective estimators of 

perceived speech quality: perceptual transformations and distance measures. A perceptual 

transformation modifies a representation of an audio signal in a way that is approximately 

equivalent to the human hearing process. A distance measure reflects the magnitude of a 

perceived distance between two perceptually transformed signals. 

We then describe a new objective estimation approach that uses a simple but effective perceptual 

transformation and a distance measure that consists of a hierarchy of measuring normalizing 

blocks. Each measuring normalizing block integrates two perceptually transformed signals over 

some time or frequency interval to determine the average difference across that interval. This 

difference is then normalized out of one signal, and is further processed to generate one or more 

measurements. The resulting new estimators, and several established estimators, are thoroughly 

evaluated and compared in Part II of this paper. Hierarchical structures of measuring normalizing 

blocks, or other structures of measuring normalizing blocks may also address open issues in 

perceived audio quality estimation, layered speech or audio coding, automatic speech or speaker 

recognition, audio signal enhancement, and other areas. 

157
Abstract, Part II 

Part I of this paper describes a new approach to the objective estimation of perceived speech 

quality. This new approach uses a simple but effective perceptual transformation and a distance 

measure that consists of a hierarchy of measuring normalizing blocks. Each measuring 

normalizing block integrates two perceptually transformed signals over some time or frequency 

interval to determine the average difference across that interval. This difference is then

normalized out of one signal, and is further processed to generate one or more measurements. In 

Part II, the resulting estimates of perceived speech quality are correlated with the results of nine 

subjective listening tests. Together, these tests include 219 4-kHz bandwidth speech codecs, 

transmission systems, and reference conditions, with bit rates ranging from 2.4 to 64 kb/s. When 

compared with six other estimators, significant improvements are seen in many cases,

particularly at lower bit rates, and when bit errors or frame erasures are present. These 

hierarchical structures of measuring normalizing blocks, or other structures of measuring 

normalizing blocks may also address open issues in perceived audio quality estimation, layered 

speech or audio coding, automatic speech or speaker recognition, audio signal enhancement, and 

other areas. 

158
Papers from the 2000s 

Pressure-induced shift and broadening of 1510–1540 acetylene wavelength calibration lines 

 William C. Swann and Sarah L. Gilbert, 2000 161 

An optical clock based on a single trapped Hg+ ion 

 Scott A. Diddams, Thomas Udem, Kurt R. Vogel, Chris W. Oates, E.A. Curtis, W. David Lee, 

 Wayne M. Itano, Robert E. Drullinger, James C. Bergquist, and Leo Hollberg, 2001 162 

Weather radar for remote sensing:

1. On the use of radar depolarization ratios for estimating shapes of ice hydrometeors in winter 

clouds 

 Sergey Matrosov, Roger Reinking, Robert Kropfli, Brooks Martner, 

and Bruce Bartram, 2001 163 

2. Evaluation of a 45-deg slant quasi-linear radar polarization state for distinguishing drizzle 

droplets, pristine ice crystals, and less regular ice particles 

 Roger Reinking, Sergey Matrosov, Robert Kropfli, and Bruce Bartram, 2002 163 

The temporal and spectral characteristics of ultrawideband signals 

William A. Kissick, 2001 165 

Tropical origins for North Atlantic climate change 

 Martin P. Hoerling, Taiyi Xu, and James W. Hurrell, 2001 166 

Wideband model of HF atmospheric radio noise 

John J. Lemmon, 2001 167 

Accuracy evaluation of NIST-F1 

 Steven R. Jefferts, Jon H. Shirley, Thomas E. Parker, Thomas P. Heavner, Dawn M. 

 Meekhof, Craig W. Nelson, Robert E. Drullinger, Leo Hollberg, W. David Lee, 

 Fred L. Walls, Filippo Levi, Giovanni Costanzo, and Andrea DeMarchi, 2002 168 

Increase in the Asian SW monsoon during the past four centuries 

 David M. Anderson, Jonathan T. Overpeck, and Anil K. Gupta, 2002 169 

On determining the maximum emissions from electrically large sources 

 Perry F. Wilson, David A. Hill, and Christopher L. Holloway, 2002 170 

Video quality measurement techniques 

 Stephen Wolf and Margaret Pinson, 2002 171 

The perfect ocean for drought 

 Martin P. Hoerling and Arun Kumar, 2003 172 

159
160
Pressure-induced shift and broadening of 1510–1540 acetylene wavelength 

calibration lines 

William C. Swann and Sarah L. Gilbert 

 NIST Optoelectronics Division 

Journal of the Optical Society of America B, 17: 1263–1270, 2000 

Significance

This paper provided the technical basis for the first of a family of Standard Reference Material 

(SRM) wavelength standards for optical communications. During the development of 

wavelength-division-multiplexed (WDM) optical communications systems, these SRMs were in 

great demand; nearly 200 have been sold, and they are used as primary standards in most 

laboratories involved in optical communications throughout the world. Similar standards have 

been incorporated into commercial optical spectrum analyzers. 

Abstract 

We have measured the line centers and the pressure-induced shifts of 14 lines in the 3ν

rotational-vibrational band of carbon monoxide, 12C160, and 18 lines in the corresponding band 

of 13C16O. These lines can be used as wavelength references in the optical fiber communication 

wavelength-division multiplexing L band (approximately 1565–1625 nm). The 12C16O spectrum

has useful reference lines from 1560 to 1595 nm, and the 13C16O spectrum has lines from 1595 to 

1630 nm. We observed that, except for a shift of 35 nm toward longer wavelengths for the 

13C16O spectrum, the behaviors of the two isotopic species are similar. We found that the 

pressure shift varies with line number, from ~+0.01 to +0.02 pm/kPa (~0.16 to 0.31 MHz/Torr). 

In addition, we measured the pressure broadening of these lines; we found that it also varies with 

line number and is typically 0.3–0.4 pm/kPa (approximately 5–7 MHz/Torr). 

161
An optical clock based on a single trapped Hg+ ion 

Scott A. Diddams, Thomas Udem, Kurt R. Vogel, Chris W. Oates, E.A. Curtis, W. David Lee, 

Wayne M. Itano, Robert E. Drullinger, James C. Bergquist, and Leo Hollberg 

 NIST Time and Frequency Division 

Science, 293: 825-293, August 3, 2001 

Significance

While the uncertainty of the current NIST-F1 laser-cooled atomic fountain clock is equivalent to 

about 1 second in 30 million years, there is a fundamental limitation on improving its accuracy: 

it uses a microwave transition dividing the second into approximately 9.2 billion “ticks.” Using a 

transition with many more “ticks” per second enables the second to be more accurately realized. 

This paper describes an atomic clock based on a transition in a laser-cooled and trapped mercury 

ion at 282 nm (ultraviolet), dividing the second into about 1.1 million billion “ticks,” with the 

potential to be up to 1,000 times more accurate than the NIST-F1 clock. This paper also 

demonstrates both a strong candidate for a future optical clock to replace the cesium-atom-based 

standard, and the means for accurately disseminating time and frequency standards from it. The 

microwave standard is relatively easy to disseminate, but the optical frequency standard is not. 

The paper describes the use of an optical frequency “comb” to directly link optical transitions to 

microwave transitions. The “comb” consists of an array of very sharp laser lines spanning a 

broad spectral range, and differing in frequency from each other by a precise and controllable 

amount, like the teeth of a comb. The researchers demonstrated that the mercury ion transition at 

about 1.1 × 1015 Hz could be directly compared to a sub-multiple of the cesium atom atomic 

clock transition. Improvement in atomic clocks has led to transforming commercial applications, 

such as the Global Positioning System and cellular communications networks, and to new 

scientific applications such as precision tests of quantum mechanics, relativity, and astrophysics. 

Abstract 

Microwave atomic clocks have been the de facto standards for precision time and frequency 

metrology over the past 50 years, finding widespread use in basic scientific studies, 

communications, and navigation. However, with its higher operating frequency, an atomic clock 

based on an optical transition can be much more stable. We demonstrate an all-optical atomic 

clock referenced to the 1.064-petahertz transition of a single trapped 199Hg+

 ion. A clockwork 

based on a mode-locked femtosecond laser provides output pulses at a 1-gigahertz rate that are 

phase-coherently locked to the optical frequency. By comparison to a laser-cooled calcium

optical standard, an upper limit for the fractional frequency instability of 7 × 10-15

 is measured in 

1 second of averaging—a value substantially better than that of the world’s best microwave 

atomic clocks. 

162
Weather radar for remote sensing: 

1. On the use of radar depolarization ratios for estimating shapes of ice 

hydrometeors in winter clouds 

Sergey Matrosov 

 NOAA Environmental Technology Laboratory/CIRES 

Roger Reinking, Robert Kropfli, Brooks Martner, and Bruce Bartram 

 NOAA Environmental Technology Laboratory 

Journal of Applied Meteorology, 40: 479–490, 2001 

2. Evaluation of a 45-deg slant quasi-linear radar polarization state for 

distinguishing drizzle droplets, pristine ice crystals, and less regular ice 

particles 

Roger Reinking, Sergey Matrosov, Robert Kropfli, and Bruce Bartram

 NOAA Environmental Technology Laboratory 

Journal of Atmospheric and Oceanic Technology, 19: 296–321, 2002 

Significance

These companion papers, which unite new theory (Matrosov et al.) and corresponding 

experimental verification (Reinking et al.), represent the culmination of a 10-year series of 

specialized weather radar development efforts to devise methods and hardware that identify 

cloud hydrometeors by their physical characteristics in order to isolate by remote sensing those 

types of particles that cause aircraft icing. These efforts and publications resulted in a 2001 U.S. 

Department of Commerce Gold Medal Award, and the Federal Aviation Administration’s 

Administrator’s 2002 Excellence in Aviation Award.

Abstract 1 

An approach is suggested to relate measurements of radar depolarization ratios and aspect ratios 

of predominant hydrometeors in nonprecipitating and weakly precipitating layers of winter 

clouds. The trends of elevation angle dependencies of depolarization ratios are first used to 

distinguish between columnar-type and plate-type particles. For the established particle type, 

values of depolarization ratios observed at certain elevation angles, for which the influence of 

particle orientation is minimal, are then used to estimate aspect ratios when the information on 

particle effective bulk density is assumed or inferred from other measurements. The use of 

different polarizations, including circular, slant-45° linear, and two elliptical polarizations is 

discussed. These two elliptical polarizations are quasi-circular and quasi-slant-45° linear, and 

both are currently achievable with the National Oceanic and Atmospheric Administration 

Environmental Technology Laboratory’s Ka-band radar. In comparison with the true circular and 

true slant-45° linear polarizations, the discussed elliptical polarizations provide a stronger signal 

163
in the “weak” radar receiving channel; however, it is at the expense of diminished dynamic range 

of depolarization ratio variations. For depolarization measurements at the radar elevation angles 

that do not show much sensitivity to particle orientations, the available quasi-circular 

polarization provides a better depolarization contrast compared to the available quasi-slant-4So 

linear polarization. The use of the proposed approach is illustrated with the experimental data 

collected during a recent field experiment. It is shown that it allows successful differentiation 

among pristine planar crystals, rimed planar crystals, long columns, blocky columns, and 

graupel. When a reasonable assumption about particle bulk density is made, quantitative 

estimates of particle aspect ratios from radar depolarization data are in good agreement with in 

situ observations. This approach can be used to detect super-cooled liquid droplets. 

Abstract 2

A remote sensing capability is needed to detect clouds of super-cooled, drizzle-sized droplets, 

which are a major aircraft icing hazard. Discrimination among clouds of differing ice particle 

types is also important because both the presence and type of ice influence the survival of liquid 

in a cloud and the chances for occurrence of these large, most hazardous droplets. This work 

shows how millimeter-wavelength dual-polarization radar can be used to identify these differing

hydrometeors. It also shows that by measuring the depolarization ratio (DR), the estimation of 

the hydrometeor type can be accomplished deterministically for drizzle droplets; ice particles of 

regular shapes; and to a considerable extent, the more irregular ice particles, and that

discrimination is strongly influenced by the polarization state of the transmitted microwave 

radiation. Thus, appropriate selection of the polarization state is emphasized. 

The selection of an optimal polarization state involves trade-offs in competing factors such as the 

functional dynamic range of DR, sensitivity to low-reflectivity clouds, and insensitivity to 

oscillations in the settling orientations of ice crystals. A 45° slant, quasi-linear polarization state, 

one in which only slight ellipticity is introduced, was found to offer a very good compromise, 

providing considerable advantages over standard horizontal and substantially elliptical 

polarizations. This was determined by theoretical scattering calculations that were verified 

experimentally in field measurements conducted during the Mount Washington Icing Sensors 

Project (MWISP). A selectable-dual-polarization Ka-band (8.66 mm wavelength) radar was 

used. A wide variety of hydrometeor types was sampled. Clear differentiation among planar 

crystals, columnar crystals, and drizzle droplets was achieved. Also, differentiation among 

crystals of fundamentally different shapes (aspect ratios) within each of the planar and columnar 

families was found possible. These distinctions matched calculations of DR, usually to within 1 

or 2 dB. The results from MWISP and from previous experiments with other polarizations have 

demonstrated that the agreement between theory and measurements by this method is repeatable. 

Additionally, although less rigorously predicted by theory, the field measurements demonstrated 

substantial differentiation among the more irregular and more spherical ice particles, including 

aggregates, elongated aggregates, heavily rimed dendrites, and graupel. Measurable separation 

between these various irregular ice particle types and drizzle droplets was also verified. 

164
The temporal and spectral characteristics of ultrawideband signals 

William A. Kissick 

 NTIA Institute for Telecommunication Sciences 

NTIA Report 01-383, January 2001 

Significance

This report broke new ground in the understanding of how ultrawideband (UWB) signals can be 

measured, characterized, and regulated, and how they interfere with traditional narrowband radio 

services. With nanosecond pulse widths and bandwidths that can span several GHz of spectrum,

UWB devices (for radio communications, sensing, and imaging) spread their energy “thinly” 

across many bands of the radio spectrum. Because these bands are in use by other services, UWB 

represents a great challenge to spectrum management. To study UWB devices, new measurement 

techniques had to be used, and new analysis techniques developed. Performed at a time of 

widespread erroneous technical claims about UWB interference, this report provided the first 

comprehensive technical basis for subsequent UWB work by many other researchers. It is 

expected to become the “classic” for measurement and characterization of UWB signals. No 

report of similar thoroughness has been produced by other researchers, nor is one expected. 

Abstract 

Ultrawideband (UWB) technology, useful for both communication and sensing applications, uses 

the radio spectrum differently than the vast majority of radiocommunication technologies. UWB 

systems make use of narrow pulses and time-domain signal processing. Questions regarding how

these systems, with their potentially very wide emission bandwidths, might affect the efficient 

use of the radio spectrum or cause interference to conventional radio and wireless systems must 

be answered before there is any large-scale deployment of UWB systems. The investigation 

reported here examined both the temporal and spectral characteristics of UWB signals, since all 

radio signals exist in both the time and frequency domains. The investigation was approached 

with theoretical analyses, measurement of actual UWB devices, and computer simulations. The 

emissions of several UWB transmitters were measured under controlled, and repeatable, 

laboratory conditions. Those measurement methods useful for routine measurements using 

commercially available test equipment were identified. The characteristics of an aggregate of 

several UWB signals were examined. An initial assessment of the effects of UWB signals on 

several Federal Government systems was accomplished through field measurements. This report 

provides a basis for an assessment of the effects of UWB signals on other communication and 

radar systems, the study of the spectrum efficiency of UWB technologies, and the development 

of spectrum sharing policies and regulations. 

165
Tropical origins for North Atlantic climate change

Martin P. Hoerling and Taiyi Xu 

 NOAA/CIRES Climate Diagnostics Center 

James W. Hurrell 

 National Center for Atmospheric Research

Science, 292: 90–92, 2001 

Significance

The paper shows that North Atlantic climate change over recent decades is consistent with a 

warming trend of the tropical Indian and Pacific oceans. It thus opened an entirely new focus of 

future research inquiry on the nature of the link between the tropical eastern hemisphere 

oceans—the warm pool in particular—and North Atlantic climate. The theory put forth is that 

this change is a regional fingerprint of anthropogenic influence, and it thereby provides a 

scientific rationale for projecting a sustained, future climatic disruption over the North 

Atlantic/Eurasian sector. The paper offers compelling basic scientific evidence for the origin of

recent climate change over the North Atlantic, identifying the agent and the process forcing 

decadal climate change. It improves climate information on the joint environmental change of 

oceans and climate, thus providing a new scientific basis for decision and policy-making. It also 

provides a new basis for improved climate predictions of North Atlantic climate and its environs, 

based on the impact of the Indo-Pacific Ocean. In so doing, it offers a new tool for both seasonal 

and decadal climate prediction, augmenting the well-known El Niño predictability. This widely 

cited publication has helped motivate new scientific efforts, including an enhanced observing 

system over the Indo-Pacific Ocean, to capitalize on the potential climate predictability. 

Abstract 

Evidence is presented that North Atlantic climate change since 1950 is linked to a progressive 

warming of tropical sea surface temperatures, especially over the Indian and Pacific Oceans. The 

ocean changes alter the pattern and magnitude of tropical rainfall and atmospheric heating, the 

atmospheric response to which includes the spatial structure of the North Atlantic Oscillation 

(NAO). The slow, tropical ocean warming has thus forced a commensurate trend toward one 

extreme phase of the NAO during the past half-century. 

166
Wideband model of HF atmospheric radio noise 

John J. Lemmon 

 NTIA Institute for Telecommunication Sciences 

Radio Science, 36(6): 1385–1391, November–December 2001 

Significance

This paper presents an original model for simulating high-frequency (HF) atmospheric radio 

noise, essential for predicting the behavior of communications systems in the HF bands. It is part 

of a research program at ITS dating back to the 1970s that included the development of a channel 

simulator to test HF radio performance in the laboratory, and models of actual propagation as 

well as this model of atmospheric noise and interference, which can be a real problem in the 

congested HF bands. Communications technologies such as spread spectrum and advanced 

digital signal processing techniques are being applied to HF wideband communications systems, 

which, because they are covert (almost undetectable), have military applications. Since many 

uncertainties exist concerning the performance of these systems, accurate noise models are 

essential. The methodology presented in this paper provides a strong foundation for testing and 

evaluation for new systems well into the future. 

Abstract 

A model of the waveform generated by high-frequency atmospheric radio noise is presented. 

Cumulative probability distributions of the noise envelope are derived and shown to be in good 

agreement with a large database collected from a wide range of noise environments. The model 

includes correlations in the waveforms that simulate the burst structure of measured atmospheric 

noise. The bandwidth dependence of the voltage deviation parameter, which parameterizes the 

impulsiveness of the noise, shows behavior that is qualitatively similar to a limited amount of 

measured data. 

167
Accuracy evaluation of NIST-F1 

Steven R. Jefferts, Jon H. Shirley, Thomas E. Parker, Thomas P. Heavner, Dawn M. Meekhof, 

Craig W. Nelson, Robert E. Drullinger, Leo Hollberg, W. David Lee, and Fred L. Walls 

 NIST Time and Frequency Division 

Filippo Levi 

 Instituto Elettrotecnico Nazionale, Italy 

Giovanni Costanzo and Andrea DeMarchi 

 Politecnico di Torino, Italy 

Metrologia, 39: 321-336, January 1, 2002 

Significance

This paper describes the current U.S. national standard for time and frequency, the NIST-F1 

laser-cooled atomic fountain clock. NBS created the world’s first atomic clock in 1949, based on 

transitions in ammonia molecules. In 1952, NBS adapted the science and technology to beams of 

cesium atoms, and through the 1990s continually improved the performance of atomic clocks 

based on cesium beams. But using thermal beams with relatively hot atoms causes a fundamental 

limit to how precisely the measurements can be made because the rapidly moving atoms have 

significant Doppler shifts and can only be observed for a relatively short time. After NBS’s first 

demonstration of laser-cooling in 1978, it was realized that atomic clock accuracy could be 

greatly improved by cooling the atoms to near absolute zero, drastically reducing the Doppler 

shift and enabling much longer measurement times. This paper describes the first full 

characterization and uncertainty analysis for NIST’s first laser-cooled atomic fountain clock, 

NIST-F1. When first operated in 1999, NIST-F1 had an uncertainty equivalent to about 1 second 

in 15 million years, and it has improved to about 1 second in 30 million years. The improvement 

of atomic clocks over the past decades, with accuracy improving by about a factor of 10 per 

decade, has enabled many transforming commercial and scientific applications. 

Abstract 

The evaluation procedure of a new laser-cooled caesium fountain primary frequency standard 

developed at the National Institute of Standards and Technology (NIST) is described. The new 

standard, NIST-F1, is described in some detail and typical operational parameters are discussed. 

Systematic frequency biases for which corrections are made—second-order Zeeman shift, blackbody radiation shift, gravitational red shift and spin-exchange shift—are discussed in detail. 

Numerous other frequency shifts are evaluated, but are so small in this type of standard that

corrections are not made for their effects. We also discuss comparisons of this standard both with 

local frequency standards and with standards at other national laboratories.

168
Increase in the Asian SW monsoon during the past four centuries 

David M. Anderson and Jonathan T. Overpeck 

 NOAA National Climatic Data Center, Paleoclimatology Program

Anil K. Gupta 

 Indian Institute of Technology, Khragpur, India 

Science, 297: 596–599, 2002 

Significance 

This record is the first paleo reconstruction of the monsoon during the last millennium, is five 

times longer than the 140-year instrumental record of the monsoon, and reveals centennial scale 

variability in addition to a long term trend. The research is significant because it supports the 

idea that the monsoon winds may increase in coming decades as the northern hemisphere 

continues to warm. These changes may affect a vast region of heavily populated Asia, with 

significant impacts on agriculture and other industries. This report and a companion paper 

received significant media attention, including National Public Radio and British Broadcasting 

Service interviews, a National Geographic television interview, and a perspectives review in 

Science. The papers had 6 citations each in the Science Citation Index within the first 12 months. 

 

Abstract 

Climate reconstructions reveal unprecedented warming in the past century; however, little is 

known about trends in aspects such as the monsoon. We reconstructed the monsoon winds for 

the past 1000 years using fossil Globigerina bulloides abundance in box cores from the Arabian 

Sea and found that monsoon wind strength increased during the past four centuries as the 

Northern Hemisphere warmed. We infer that the observed link between Eurasian snow cover and 

the southwest monsoon persists on a centennial scale. Alternatively, the forcing implicated in the 

warming trend (volcanic aerosols, solar output, and greenhouse gases) may directly affect the 

monsoon. Either interpretation is consistent with the hypothesis that the southwest monsoon 

strength will increase during the coming century as greenhouse gas concentrations continue to 

rise and northern latitudes continue to warm. 

169
On determining the maximum emissions from electrically large sources 

Perry F. Wilson, David A. Hill, and Christopher L. Holloway 

 NIST Radio-Frequency Technology Division 

IEEE Transactions on Electromagnetic Compatibility, EMC-44(1): 79–86, February 2002 

Significance

This paper develops theory based estimates for the directivity of an unintentional emitter. The 

directivity estimate can be combined with straightforward measurements of the total radiated 

power from a device to estimate the maximum emissions from the device and hence potential of 

the device to cause electromagnetic interference. Numerical simulations and measured data show 

the effectiveness of the approach. The results presented in this paper directly impact 

electromagnetic compatibility (EMC) testing of devices whose dimensions are large compared to 

a wavelength. The results also directly impact the development of EMC standards for 

frequencies above 1 GHz (the present upper bound for most EMC emissions testing). The results 

in the paper should lead to reduced test times. Reduced test times will have a significant 

economic impact because of existing requirements that all digital devices sold in the US, the 

European Community, and many other world markets must satisfy emission test limits. The 

paper was awarded the 2003 IEEE EMC Transactions Prize Paper Award (for papers published 

in 2002) and the 2002 EEEL Outstanding Authorship Award. 

Abstract 

This paper examines the use of measurements of the total radiated power from an arbitrary 

source, combined with theory-based estimates of directivity or quality factor, to accurately 

predict the maximum electric field radiated by the source either at a line-of-sight distance or in a 

resonant volume. The approach using total radiated power avoids source rotations during testing 

and is an efficient alternative to current emission test methods. Examples of simulated (random

source set) and measured (box with holes) planar-cut radiation-patterns for electrically large 

sources are presented. Both simulated and measured data agree well with theoretical estimates. 

170
Video quality measurement techniques 

Stephen Wolf and Margaret Pinson 

 NTIA Institute for Telecommunication Sciences 

NTIA Report 02-392, June 2002 

Significance

This NTIA Report describes an ITS-developed objective video quality metric (VQM) capable of 

accurately predicting the subjective (human viewer) evaluations of transmitted video signals for 

a wide range of source video characteristics (e.g., spatial detail, motion) and system impairments 

(e.g., compression, transmission error, data loss). The VQM has been standardized nationally and 

internationally, patented, licensed, and implemented in computer-based test equipment. The 

underlying mathematical algorithms are highly innovative, and the computer-based techniques 

for emulating human perception and judgment first described here are now accepted worldwide. 

Abstract 

Objective metrics for measuring digital video performance are required by Government and 

industry for specification of system performance requirements, comparison of competing service 

offerings, service level agreements, network maintenance, and optimization of the use of limited 

network resources such as transmission bandwidth. To be accurate, digital video quality 

measurements must be based on the perceived quality of the actual video being received by the 

users of the digital video system rather than the measured quality of traditional video test signals 

(e.g., color bar). This is because the performance of digital video systems is variable and depends 

upon the dynamic characteristics of both the original video (e.g., spatial detail, motion) and the 

digital transmission system (e.g., bit rate, error rate). The goal of this report is to provide a 

complete description of the ITS video quality metric (VQM) algorithms and techniques. The ITS 

automated objective measurement algorithms provide close approximations to the overall quality 

impressions, or mean opinion scores, of digital video impairments that have been graded by 

panels of viewers. 

171
The perfect ocean for drought

Martin P. Hoerling and Arun Kumar 

 NOAA/CIRES Climate Diagnostics Center

Science, 299: 691–694, 2003 

Significance

The results described in this paper provide a new theory for the role of oceans in drought, and 

illuminate new avenues for long-lead prediction of drought. The results also reveal new evidence 

for an anthropogenic influence on climate at the regional scale. The warmth of Indo-west Pacific 

ocean temperatures that played a role in the 1998–2002 drought is consistent with the ocean’s 

response to changing atmospheric chemistry, and was not solely due to natural variability. In this 

regard, the study is significant for identifying the atmospheric sensitivities to recent changes in 

tropical ocean states that can be capitalized upon for regional climate change projections in the 

21st Century. 

This paper has been highly recognized by scientists and the popular media. It was highlighted in 

a non-technical article in Science by Richard Kerr, as well as in the interagency Climate Change 

Science Program’s report of outstanding accomplishments to congress in “Our Changing Planet” 

and in the Encyclopedia Britannica’s annual update on outstanding scientific advances.

Abstract

The 1998–2002 droughts spanning the United States, southern Europe, and Southwest Asia were 

linked through a common oceanic influence. Cold sea surface temperatures (SSTs) in the eastern 

tropical Pacific and warm SSTs in the western tropical Pacific and Indian oceans were 

remarkably persistent during this period. Climate models show that the climate signals forced 

separately by these regions acted synergistically, each contributing to widespread mid-latitude

drying: an ideal scenario for spatially expansive, synchronized drought. The warmth of the 

Indian and west Pacific oceans was unprecedented and consistent with greenhouse gas forcing. 

Some implications are drawn for future drought.

172
Author Index 

A 

Akima, Hiroshi, 44

Alexander, Michael A., 140 

Allan, David W., 29, 116 

Allwine, Eugene J., 106 

Anderson, David M., 169

Anderson, David N., 53

B 

Baker-Jarvis, James, 122 

Barger, Richard L., 52 

Barnes, James A., 29 

Barrick, Donald E., 68 

Barsis, Albrecht P., 28 

Bartram, Bruce, 163

Baugh, Kimberly E., 152 

Bean, Bradford R., 32 

Beehler, Roger E., 19 

Benjamin, Stanley G., 126 

Bergquist, James C., 162 

Berry, Leslie A., 26

Blackmon, Maurice L., 135 

Bradley, Raymond, 147

Brady, Charles H., 104 

Brennan, J.A., 51 

Brewster, Keith A., 126 

Brümmer, Renate, 126 

Bruno, Thomas J., 111

Buhr, Martin P., 106 

Bussey, Howard E., 56

Butler, James H., 131 

C 

Caracena, Fernando, 63, 75 

Case, Roslyn, 147 

Chamberlain, George E., 91 

Chappell, Charles F., 75

Childs, Greg E., 54 

Chivers, Hugh J.A., 23 

Churney, Kenneth L., 45

Clark, Alan F., 65, 66, 97, 108

Codrescu, Mihail V., 138 

Cohen, Robert S., 48

Costanzo, Giovanni, 168 

Crawford, Myron L., 55 

Crow, Edwin L., 13

Cummings, Scott O., 131 

Curtis, E.A., 162 

D 

Dally, James W., 129, 132 

Danielson, Bruce L., 52, 91

Davies, Kenneth, 27 

Davis, Dickie D., 116

Davis, Ethan R., 152 

Day, Gordon W., 52, 91

Daywitt, William C., 92

Dean, J.W., 51 

DeMarchi, Andrea, 168 

Derr, Vernon E., 43 

Deser, Clara, 135, 140 

Diddams, Scott A., 162 

Disney, Robert T., 57

Dlugokencky, Edward J., 128 

Douglas, Maryanne, 147 

Drullinger, Robert E., 73, 93, 162, 168 

Dubé, William P., 145

Dutton, Evan J., 32 

E 

Earnshaw, Kenneth B., 98

Eichenberger, Ali L., 155 

Ekin, Jack W., 65, 66, 100, 110

Elkins, James W., 131 

Elvidge, Christopher D., 152 

Ely, James F., 86 

Engen, Glenn F., 12, 76 

Ericks, Lewis J., 54 

Evans, David S., 58

Evans, Michael W., 68

Evenson, Kenneth M., 52, 67, 93

F 

Fehsenfeld, Fred C., 33, 106 

Ferguson, Eldon E., 33 

Fickett, Fred R., 65, 66, 90 

Finney, Bruce, 147 

Fisher, Donald A., 131 

Fitting, Dale W., 145

Flynn, Thomas M., 71 

Franzen, Douglas L., 91 

Frederick, Nolan V., 47, 61

Friend, Daniel G., 107

Fujita, Tetsuya T., 63

Fuller-Rowell, Tim J., 138

Fung, Inez, 123 

173
G 

Gajewski, Konrad, 147 

Gallagher, John G., 134

Gallawa, Robert L., 91

Garcia, Rolando R., 102

Gardner, Robert S., 13 

Gilbert, Sarah L., 161

Goldfarb, Ron B., 124 

Goodrich, Loren F., 90, 108 

Goodwin, Robert D., 21

Green, John L., 60

Gupta, Anil K., 169

H 

Hale, Paul D., 133 

Hall, Bradley D., 131

Hall, John L., 52, 93 

Hamilton, Clark A., 99

Hanley, Howard J.M., 86 

Hardy, Douglas, 147

Haynes, William M., 61, 95, 151

Heavner, Thomas P., 168 

Herbstreit, Jack W., 11 

Hill, David A., 82, 153, 170

Hilton, Gene C., 146 

Hiza, Michael J., 61, 95, 151 

Hoer, Cletus A., 64, 76 

Hoerling, Martin P., 149, 166, 172 

Hollberg, Leo, 162, 168

Holloway, Christopher L., 170

Holt, John M., 156 

Hord, Jesse, 87 

Howard, Carleton J., 67

Hoxit, L. Ray, 75 

Huber, Marcia L., 134 

Hufford, George A. , 88, 125

Hughen, Konrad, 147

Hurrell, James W., 166 

I 

Irwin, Kent D., 146 

Itano, Wayne M., 142, 162

J 

Jacoby, Gordon, 147 

Jefferts, Steven R., 168 

Jennings, Anne, 147

Jennings, Donald A., 31, 93 

Jewett, Brian F., 126 

Johnson, Victor J., 35 

K 

Kamper, Robert A., 49 

Kanda, Motohisa, 81 

Kaplan, Steven B., 65 

Kasen, M. Bud, 62 

Kautz, Richard L., 99 

Keller, Mark W., 155 

Kerns, David M., 85

Kihn, Eric A., 152 

Kim, Ernest M., 91 

King, Brian E., 142, 144

Kissick, William A., 88, 122, 165

Kneebone, C.H., 51

Kroehl, Herbert W., 152

Kropfli, R., 163 

Ku, Harry C., 108 

Kumar, Arun, 149, 172 

L 

Lamoureux, Scott, 147

Lang, Patricia M., 128

Lasca, Andrew, 147 

Lawrence, Robert S., 23 

Layer, Howard P., 93

Ledbetter, Hassel M., 62 

Lee, W. David, 162, 168 

Leinbach, Harold, 16

Lelental, Mark , 124 

Lemmon, John J., 167 

Levi, Filippo, 168

Levine, Judah, 116 

Liebe, Hans J., 112, 125 

Little, C. Gordon, 16, 23, 37, 43

Liu, Shaw C., 106 

Lloyd, Frances L., 99

Longley, Anita G., 28, 36, 88 

Louie, Beverly, 101 

M 

Ma, Mark T., 59 

MacDonald, Glen, 147 

Maddox, Robert A., 75, 94 

Magee, Joseph W., 151 

Manabe, Takeshi, 125 

Manahan, Michael P., 156 

Mann, Douglas B., 51 

Marks, Roger B., 127 

Marsh, Francis J., 156 

Martin, Russell C., 128 

Martinis, John M., 137, 146, 155 

Martner, Brooks, 163 

Masarie, Kenneth A., 128 

Matrosov, Sergey, 163 

May, Peter T., 115 

McCarty, Robert D., 50, 83, 87, 95 

McColskey, J. David, 104 

174
M

cCowan, Chris N., 114, 136, 156 

McHenry, Harry I., 62, 104

McLinden, Mark O., 134 

Mechels, Steven E., 133 

Meekhof, Dawn M., 142, 144, 168

Merritt, David A., 98

Middleton, David,69

Mikesell, R.P., 62

Mockler, Richard C., 19 

Moffett, R.J., 138 

Monroe, Chris, 142, 144

Moore, Jay, 147

Moran, KennethP., 98, 115 

Moreland, John, 100, 108

Morris, Derek,56

Morrison, Graham, 134 

N 

Nahman, Norris S., 72

Nahum, Michael, 137 

Nelson, Craig W., 168

Nesenbergs, Martin, 74 

Newell, Allen C., 109

Norton, Kenneth A., 15, 28

O 

Oates, Chris W., 162 

Olson, D.L.,114 

Ott, RandolphH., 46

Overpeck, Jonathan T., 147, 154, 169

P 

Parker, Thomas E., 168 

Parrish, David D., 106

Penland, Cécile, 143 

Petersen, F. Russell, 52, 93 

Peterson, Robert L., 110

Pinson, Margaret, 171 

Pollock, Clifford R., 93 Powell, Robert L., 54, 65

Purtscher, Patrick T., 104 

Q 

Quegan, Shaun, 138

R 

Radebaugh, Ray, 34, 65, 101

Raffo, A.G., 131 

Rainwater, James C., 107

Ravishankara, Akkihebbal R., 130 

Read, David T., 65, 84, 104, 129, 132

Reed, Richard P., 62, 84, 97 

Reinking, Roger, 163

Retelle, Michael, 147

Rice, Philip L., 28, 36

Roder, Hans M., 87 

Rowland, F. Sherwood, 102

Ruth, Earl A., 156 

S 

Sardeshmukh, Prashant D., 143 

Schlatter, Thomas W., 126

Schmeltekopf, ArthurL., 33

Scott, Russell B., 14

Seitz, Neal B., 113 

Shelton, R.N., 108 

Shirley, JonH., 168

Shives, T. Robert, 104 

Siewert, Thomas A., 114, 136, 145, 156 

Smith, David R., 101 

Smith, Ernest K., Jr., 10 

Smith, Sheldon, 147 

Smith, Tracy L., 126 Snider, Charles S., 19

Solomon,Susan, 102, 130 

Spaulding, ArthurD., 57, 69

Spies, K.P., 24 

Stamus, Peter A., 126 

Steele, L. Paul, 128 

Strauch, Richard G., 98, 115 

Sugar,George R., 25 

Sullivan, Donald B., 116

Svoronos, Paris D.N., 111 

Swann, William C., 161

Swanson, Thomas H., 131 

T 

Takahashi, Taro, 123 

Tans, PieterP., 123,128

Thompson, Curt A., 124 

Thompson, Moody C., 11 

Thompson, Thayne M., 131

Timmerhaus, Klaus D., 20

Trainer, Michael, 106 

Turnipseed, Andrew A., 130 

U 

Udem, Thomas, 162 Utlaut, William F., 4

8

V 

van de Kamp, Douglas, 98

VanZandt, Thomas E., 60 

Vanzura, Eric J., 122 

Vogel, K.R., 162 

175
Vogler, Lewis E., 89 Wolf, Stephen, 171 

Voran, Stephen, 157 Wolfe, Alex, 147 

Wollman, David A., 146 

W Woodhouse, Connie A., 154

Wuebbles, Donald J., 102

Wait, James R., 22, 24, 82

Walls, Fred L., 73, 168 X 

Warnock, James M., 60 

Warren, Rachel F., 130 Xu, Taiyi, 166 

Weber, Bob L., 68

Weber, Lloyd A., 50 Y 

Weintraub, Stanley, 10

Weiss, Marc, 116 Young, Matt, 91, 133

Wells, Joseph S., 52, 93 

Wepman, Jeffery A., 141 Z 

West, E. Dale, 45 

Westberg, Halvor H., 106 Zaltsman, E.B., 56 

Williams, Dylan F., 127 Zhong, Min, 149 

Williams, Eric J., 106 Zielinski, Greg, 147

Wilson, Perry F., 170 Zimmerman, James E., 47, 49, 71, 101 

Wineland, David J., 73, 142, 144 Zimmerman, Neil M., 155

Winkler, Richard H., 60

176
Subject Index 

A 

absolute thermometer, 49

absorption 

cell (calorimeter), 31 

earth-space radio propagation, 32

millimeter-wave propagation model (MPM), 112

 riometer, 16 

accuracy, atomic clock, 168 

acoustic radar

 clear atmosphere, 43 

 development, 37 

Radio Acoustic Sounding System, 115 

Advanced Weather Interactive Processing System 

 (AWIPS), 8 

Aeronomy Laboratory (NOAA), 6, 7, 33, 60, 98, 115

afterglow reaction, 33 

air 

conditioners, chlorofluorocarbons, 131, 134 

 quality, 106

aircraft 

 accidents, 63 

 icing, 163 

 observations, 126 

Aircraft Communications Addressing and 

Reporting System (ACARS), 126 

Alaska, 11 

Allan variance, 29

Allardice, John F., 3

All-Union Scientific-Research Institute of Physico-

 Technical and Radio-Technical Measurements 

(VNIIFTRI) (USSR), 56

alternating-field susceptometry, 124

American National Standard, 8 

American Physical Society, 108 

American Society for Testing and Materials (ASTM) 

Committee on Superconductivity, 65

E23, Standard Test Methods for Notched Bar 

Impact Testing of Metallic Materials, 156 

 superconductor measurement standard, 90 

American Welding Society, 114 

amine-absorber pressure vessel, 104 

analog-to-digital converters (ADCs), 141 

Anger function, 81

anisotropic ionosphere, 26

anomalies 

Appleton anomaly, 53

North Atlantic Ocean, 135 

ocean mixed layer, 140 

 rainfall, 149

sea surface temperature growth, 143 

Antarctic ozone hole, 7, see also ozone

antenna scattering-matrix, see PWSM

antenna-antenna interactions, 85

antennas 

 arrays, 59

 calibration, 81

 directivity, 28

 microwave, 85 

system loss, 15 

anthropogenic influence 

 chlorine compounds, 102 

 drought, oceans, 172

fluorinated gases, 130 

 methane, 128 

 non-methane hydrocarbons, 106 

North Atlantic climate change, 166 

 refrigerants, 134

 smog, 106

anvil cloud, 94 

Apollo 11 mission, 5 

Appleton anomaly, 53

apportionment boundaries, 113

Arctic, 147

area prediction mode, 88 

arrays, antenna, 59 

Asian monsoon, 169 

ASME Boiler and Pressure Vessel Code, 114 

atmosphere 

lifetimes (chemistry), 130 

 noise, 27 

 radio noise, 167

radio spectrum absorption, 112 

radio waves, 32

 refractive index, 10

 refractivity variations, 11

 residence, 130 

 turbulence, 11

Atmospheric General Circulation Model (AGCM), 149 

atomic clocks, see also NIST F1 

 accuracy, 168 

 Allan variance, 29

 laser-cooling, 73 

laser-line narrowing, 7

 NBS-1, 5 

 NBS-2, 19

 optical, 162 

atomic frequency standards, 29

attenuation

ground waves, 26, 82 

 knife-edge diffraction, 89 

long-term median values, 28 

optical fiber measurement systems, 91 

 radio signal, 32

 rates, 24 

177
attenuation—continued

stratified media models, 22

waves, irregular terrain, 46

audio quality, 8

auroral 

 physics, 58

 zone, 16 

austenitic stainless steel, 84, 114, 136

Automated Computer Time Service (ACTS), 116

Aviation Weather Center, 126 

B 

backscatter, 91 

Bakker, Robert, 7 

balloon-borne instruments, 60 

balloonsonde ozone data, 102 

bandwidth, 91

Big Thompson Storm, 75 

bioelectromagnetic effects, 81 

Blue Planet Prize, 8 

bolometer mount, 12 

Boltzman's constant, 49

Bose-Einstein Condensate, 8, 73 

Boulder Chamber of Commerce, 2 

Boulder Elks Lodge, 3 

break junctions, 100, 108 

British Antarctic Survey, 102 

broadband

 antennas, 59 

 model, 112 

six-port network analyzer, 64

business noise, 57

C 

calibration

 cryogenic flow, 51

dual six-port network analyzer, 64

Thru-reflect-line (TRL), 127

transverse electromagnetic (TEM) cells, 55 

vector network analyzers, 76 

calorimeter 

 design, 45

 measurement, 31 

Canada, 11 

capacitance standards, 137, 155 

carbon 

 dioxide (CO2)

 anthropogenic effects, 128 

Mauna Loa observatory, 5 

 sources and sinks, 123 

 emissions, 152 

cardiography, 47 

Carnahan-Starling-Desantis (CSD) equation of state, 

 134 

Carter, Jimmy (President), 6 

cavity resonators, 56 

CCIR/ITU-R model, 7 

CCITT, see ITU-T Recommendations 

cellular telephones, 141

Central Radio Propagation Laboratory (CRPL), 

1-3, 5, 6, 10, 11, 15, 23, 27, 32 

ceramic superconductors, 110 

cesium, 6, 8, 30, 168 

channel systems, 28 

Charpy impact test, 156 

chemical analysis , 111 

Cheyenne Mountain, 11

chlorine compounds, 102 

chlorofluorocarbons (CFCs) 

atmospheric lifetimes, 130 

growth rates, 131 

 reaction rates, 67

refrigerant database (REFPROP), 134

chromatography, 111 

city lights, 152 

cladding diameter, 133 

clear air 

Doppler radar, 115 

millimeter-wave propagation model, 112 

remote sensing techniques, 43

climate 

 Arctic, 147

 change 

 carbon dioxide, 123 

 drought, 154, 172

 fluorinated gases, 130 

 methane, 128 

 North Atlantic, 166

North Atlantic Ocean, 135 

 reconstructions, 169 

Climate Diagnostics Center (CDC), 8 

Climate Monitoring and Diagnostics Laboratory 

 (CMDL), 5, 7, 128, 131 

climatic time scale, 32 

clocks, see also atomic clocks, NIST-F1 

 cesium, 8, 168 

 optical, 162 

 performance, 29

 time synchronization, 116 

clouds 

 detection, 152 

radio signal attenuation, 32

 winter, 163 

coherent reception, 69

cold core system (meteorology), 94 

Colorado National Guard Armory, 3, 5 

Colorado wind-profiling network, 99

Columbia Space Shuttle, 8

commercial flight planning, 126 

communication systems 

 radio, 27

 UWB effects, 165 

178
Comprehensive Ocean-Atmosphere Data Set 

 (COADS), 135 

computer clocks, 116 

Computer Method, 44

Condon, Edward U., 2

confidence 

 belt, 13

 interval, 13

constants (mathematics), 10 

contact micrometer, 133 

Continental flight 426, 63

controlled-NOT, 142 

convection 

 downbursts, 63

 floods, 75 

 tropical, 94

cooling system designs, 134 

Cooperative Institute for Research in Environmental 

 Sciences (CIRES), 6 

coplanar waveguide, 127 

Cornell, Eric, 8

cosmic noise, 16 

Crawford Cells, 55

critical current, 66, 90 

cryocoolers, 71, 101 

cryogenic 

 equipment design, 54 

 noise, 92 

 testing, 84

 welding, 136

Cryogenic Data Center, 35

Cryogenic Engineering Conference (CEC), 20, 101 

Cryogenic Engineering Laboratory (CEL), 3, 14

Cryogenic Flow Research Facility, 51

Cryogenics Division, 65, 66, 95, 97 

cryogens, 83 

cumulus convection, 63

curved earth, 24 

customer behavior, 74

D 

Davis, Dick, 6

Debye model, 72, 125 

decadal 

climate change, 166 

 variability, 135 

decentralization of the Federal government, 2 

Defense Meteorological Satellite Program (DMSP), 

 152 

demagnetization, 124 

density 

liquified natural gas, 61

 measurements, 95 

 metrology, 21

depolarization ratio, 163

device testing, transverse electromagnetic (TEM), 55 

diabatic heating, 94

dielectric 

complex permittivity, 125

 properties, 55

digital 

devices, reduced test times, 170 

signal processing, 141 

 speech, 157 

system performance, 69

 television, 36

terrain elevation databases, 36

video quality, 171

dilution refrigerator, 34

dinosaur Drinker nisti, 7 

dipole probes, 81 

directivity, unintentional emitter, 170

discharge-flow system, 67 

distance 

 measures, 157 

 propagation characteristics, 26 

Distant Early Warming (DEW), 11 

Ditsch, Carl, 6 

Doppler 

 effect, 60 

 radar, 115 

wind profilers, 7, 98

downbursts, 63

drawing smooth curves, 44

drift , 68

drizzle, 163 

drought, 154, 172

Drinker nisti, 7 

Drullinger, Robert E., 7 

dual six-port network analyzer, 64, 76

dual-polarization radar, 163 

E 

Earth 

 curvature, 26 

 rotation, 19

stratified media models, 22

earth-ionosphere waveguide, 24 

earth-space radio propagation, 23

Echo Lake Cosmic Ray Symposium, 2 

echo-sounders, 37

economic impact, 116 

ecosystem alteration, 147 

EEEL Outstanding Authorship Award, 170 

Eisenhower, Dwight D. (President), 4 

El Niño Southern Oscillation (ENSO)

 growth, 143

North Atlantic climate effects, 166 

 prediction, 8

teleconnection patterns, 149

179
electric 

current standards, 137 

 lengths, 11

 noise, 49 

electromagnetic 

 interference, 170 

radiation hazard meters, 55 

waves, stratified media, 22

electromagnetic compatibility (EMC) 

 reverberation chambers, 153 

short dipole probes, 81

TEM cells, 55 

electron 

 beam moiré, 132 

 counting, 155 

 precipitation, 58

 pumps, 137 

electron-layer production, 27 

electron-tunneling, 100

electrothermal feedback, 146 

emissions 

electrically large sources, 170 

perfluorocarbons (PFCs), 130 

 reverberation chambers, 153 

Emmy Award, 6

empirical orthogonal function (EOF), 135

end-to-end virtual connections, 113

energy 

 companies, 95 

 gap, 100, 108

Engen calorimeter, 12 

Environmental Data Service (EDS), 6

Environmental Science Services Administration 

 (ESSA), 4, 5, 6

Environmental Technology Laboratory (ETL), 7, 8, 

 68, 115, 163

equatorial 

 anomaly, see Appleton anomaly 

 F-region, 53

Erlang formulas, 74

error 

 analysis techniques, 109 

 bars, 13 

ESSA Research Laboratory (ERL), 4, 6, 7 

Eurasian snow cover, 169

Evanson, Ken, 7 

excitation factors, 24 

explosions, 104

F 

Faller, James, 6 

Faraday rotation, 23

far-field radiation patterns, 91

Federal Aviation Administration (FAA), 126, 163 

Federal Communications Commission (FCC), 6 

Fermi-Dirac gas model, 34

ferrite, 114

Filla, Jim, 7

filler metals, 136

fine structure constant, 155 

fixed-station military radios, 141

flash floods, 75

flask sampling, 128 

flicker noise, 29

flow loop, 51

fluid property measurement, 21, 61, 83 

Fluids Pack, 83 

fluorinated gases, 130 

FM broadcasts, 15

fog, 32

Forecast Systems Laboratory (FSL), 7, 8, 60, 98 

forecasts

Colorado wind-profiling network, 98

El Niño Southern Oscillation, 149

flash floods, 75

mesoscale convective complexes, 94 

Rapid Update Cycle, 7 

severe storm, 7 

 short-term, 126

wind profilers, 60 

FORTRAN, 83

fossil Globigerina bulloides, 169 

fracture mechanics, 62 

F-region, 53

frequency

human-made radio noise, 57

ionospheric effects, 23 

 prediction, 27

Front Range (Colorado), 60, 75 

G 

Gaussian 

 hill, 46

 noise, 69 

General Circulation Model (GCM), 123 

geomagnetic 

fields, 27, 53 

storms, 16, 138

glacial melting, 147

glass beams, 100 

Glaze, David J., 7 

global 

 carbon cycle, 123 

 distance communication, 22 

warming, 147, 169 

Global Assimilation of Ionospheric Measurements 

 (GAIM) model, 53

Global Warming Potential (GWP) index, 130

gradiometer, 47

grain-boundary weak links, 110

granular superconductors, 110 

grating, 132

180
gravity waves, 138 

greenhouse gas forcing, see anthropogenic influence 

greenhouse gases, see specific type (e.g., methane)

Greenland, 11 

ground waves 

 attenuation, 26 

 transmission loss, 15 

group-path delay, 23

Guinness Book of World Records, 7 

H 

Haar-Gallagher-Kell equation of state, 134 

halogen gases, 130, 131

heaters (high-power transmitters), 48

helium liquids, 34

heterogeneous chemistry, 102

High Altitude Observatory, University of Colorado, 2

high critical temperature superconductor (HTS), 108

high-energy 

pulsed Doppler lidar, 7 

 x-ray diffraction, 145 

high-field magnets, 67

high-frequency (HF)

antenna arrays, 59

atmospheric radio noise, 167 

ionospheric beams, 48

 ionospheric propagation, 27

High-Frequency Active Auroral Research Program 

 (HAARP), 48

High-Power Auroral Stimulation (HIPAS), 48

high-temperature superconductors (HTS), 110

human 

 health, 106 

 perception, 171

 made, see anthropogenic influence 

humidity, 32 

hydrocarbons, 106 

hydrogen, 87, 104

hydrometeors, 163 

hydroperoxyl radicals, 67

I 

ice 

 clouds, 102

 cores, 128 

 crystals, 163

IEEE EMC Transactions Prize Paper Award, 170 

immunity measurements, 153 

impedance, 76, 127 

impulsive interference, 69

incoherent reception, 69 

Indo-Pacific Ocean, 143, 166, 172 

Industrial Revolution, 128

inspector training, 104 

Institute for Telecommunication Sciences (ITS), 

 6, 7, 8 

Institute for Telecommunication Sciences and 

 Aeronomy (ITSA), 4, 5, 6 

Institutes for Environmental Research, 6

instrumentation, chemical, 111 

integral equation, radio wave propagation, 46

Integrated Services Digital Network (ISDN), 113

interference 

 impulsive, 69

satisfactory service requirements, 28 

intergranular Josephson junctions, 110 

internal climate system, 147

International Cryocooler Conference (ICC), 71 

International Electrotechnical Commission (IEC), 90 

International Geophysical Year (IGY), 5, 27

International Organization for Standardization (ISO), 

 65, 134 

International Radio Consultative Committee (CCIR), 

 57 

International Reference Ionosphere (IRI), 138 

International Year of the Quiet Sun, 27

Internet Protocol (IP) networks, 113 

Internet Time Service (ITS), 116

interpolation, mathematical method, 44

ionosphere 

 absorption, 16

 chemistry, 33 

F2 region, 53

geomagnetic storms, 138 

layered model, 24

 meteor trails, 25

radio wave effects, 23

radio wave modification, 48 

radio wave propagation, 27

reflection coefficient, 26 

stratified media models, 22

wave hop theory, 26 

Iowa State University, 108 

irregular terrain integral equation, 46

Irregular Terrain Model (ITM)

point-to-point methods, 28 

tropospheric radio transmission loss, 36

 user's guide, 88 

isentropic analysis, 126

isochoric gas expansion, 151 

isoperibol calorimetry, 45

ITS Irregular Terrain Model (ITM), 

 see Irregular Terrain Model 

ITU-T Recommendations, 113

J 

Jennings, Donald, 5

Jesperson, James, 6 

John F. Kennedy International Airport, 63

Johnson noise, 49 

181
Joint Institute for Laboratory Astrophysics (JILA), 

 4, 6, 8 

Josephson 

 Effect, 49 

 phenomena, 65

 voltage standard, 99

Junction Model, 110

K 

Ka-band radar, 163 

Kallistratova, M.A., 37

Kamas, George, 6 

Ketterle, Wolfgang, 8 

kinetic schemes, 67

knife-edge diffraction, 89 

krypton, 93

L 

La Niña, see El Niño Southern Oscillation

Labrador Sea, 135 

land mobile radio (LMR), 8 

land-mobile system applications, 88

Large Coil Project, 84

large-scale convection, 94 

laser 

 cooling 

 clocks see atomic clocks 

 origination, 73 

 quantum logic gate, 142 

 superposition, 144

 energy standard, 31 

 measurements 

 calorimeter, 45 

 methane-stabilized, 52 

 speed of light, 93 

laser-magnetic resonance detection, 67

length measurement, 122 

lidar, 7, 43

linchpin reaction, 67 

linear arrays, 59 

liquefied natural gas (LNG), 61, 95 

liquid 

 density measurements, 95 

helium, 34, 71

 hydrogen, 3, 5 

 methane, 61 

nitrogen, 51, 92

liquification of gases, 14 

listening tests, 157 

Little Ice Age, 147

local time, 138 

locally optimum Bayes detection (LOBD) receivers, 

 69 

log-periodic dipole array, 59

long distance 

 communication, 25

 propagation, 26

longitude 

 dependence, 138 

 variability, 53

Longley-Rice Model, see Irregular Terrain Model 

Lorentzian function, 125 

loss measurements, 56 

lossy ground, 59

low latitude ionosphere, 53

low temperature measurements 

 materials, 97 

 vapors , 107

Lowe, John P., 7 

lower atmosphere

 probing, 37

radio wave propagation, 32

low-frequency radio waves, 26

M 

magnesium ions, 73

magnetic

 latitude, 53 

 susceptibility, 124

 suspension densimeter, 61, 95 

 field 

 aligned potential difference, 58

 Earth, 24

 Josephson junctions, 110

 weak, 47 

Magnetic Fusion Test Facility (Lawrence Livermore 

 Laboratory), 84

magneto-ionic theory, 27

magnetometer, 47

magnetospheric energy, 138

magnets, 7, 84

mapping 

city lights, 152 

ocean surface currents, 68 

“March Meeting,” American Physical Society, 108 

Marconi, Guglielmo, 2 

Markov model, 74

materials measurements, 97 

Materials Reliability Division, 8

Materials Research Society, 108 

Mauna Loa Observatory (Hawaii), 5 

McKay Helm Award, 114 

mechanical stirring, 153 

megadrought, 154 

Meissner effect, 124 

mercury ions, 162 

Mesometeorological Group, 75 

mesonetwork, 63 

Mesoscale Analysis and Prediction System (MAPS), 

 126 

182
Mesoscale Convective Complexes (MCCs), 94 

metal castings, 145

meteor trails, 25

meteorology, radio, 32

meter definition, 7, 52, 93

methane 

 greenhouse gas, 128

liquefied natural gas densities, 95

magnetic suspension densimeter, 61

thermodynamic and transport properties, 83 

methane-stabilized laser, 52 

metrological accuracy, 137 

microbursts, 63

microcalorimeter, 12, 146 

microelectronic devices, 129 

micromechanics, 132 

microwave 

 antennas, 85 

 microcalorimeter, 12 

 network analyzer, 64

 techniques, 10

military applications

 Allan variance, 29

 area predictions, 88 

fixed-station radios, 141 

high frequency bands, 167 

reverberation chamber measurements, 153

transhorizon communications, 11

VLF radio wave propagation, 24

millimeter-wave 

 bands, 5 

propagation model (MPM), 112, 125 

minimum scattering antennas, 85

mixed layer, ocean, 140 

modal interference, 143 

mode theory, 153 

model interference, 69

Modified Bennedict-Webb-Rubin (MBWR) 

 equation of state, 134 

moire, 132 

monopulse array, 59

monsoon, 169

Montreal Protocol, 131 

Mount Washington Icing Sensors Project (MWISP),

 163 

MPM, see millimeter-wave propagation model

multi-service networks, 74

N 

National Aeronautical and Space Administration 

 (NASA), 8 

National Association of Securities Dealers (NASD), 

 116 

National Geophysical Data Center (NGDC), 6 

National Medal of Science, 102 

National Meteorological Center (NMC), 126

National Ozone Expedition, 7, 102

National Research Council, Canada, 56 

National Transportation Safety Board (NTSB), 63

National Weather Service (NWS), 7, 98

 modernization, 8 

natural 

gas properties, 151 

 hydrocarbons, 106 

NBS-1, 5, see also NIST-F1

NBS-2, 19

National Bureau of Standards (NBS) Tech Note 101, 

 15, 28, 36 

Nb-Sn filament, 100 

near-field 

 measurements, 85 

radiation patterns, 91

near-infrared (NVIR) radiance, 152

negative ions, 33 

network 

 analyzer, 64 

 congestion, 74 

neural activity, 47

Newton-Raphson iteration, 81

Nicolson-Ross method, 122

nighttime lights, 152 

National Institute of Standards and Technology (NIST) 

 TN 1500-3, 145 

NIST-7, international time standard, 7

NIST-F1, see also atomic clocks 

 accuracy, 168 

atomic beam frequencies, 19 

cesium fountain clock, 8

optical clock, 162 

 radiation-pressure cooling, 73

nitrogen 

 flow loop, 51

liquefied natural gas densities, 95

magnetic suspension densimeter, 61

nitrogen

noise standard, 92

strengthened austenitic stainless steels, 84

thermodynamic and transport properties, 83 

 oxide

 hydroperoxyl radicals reaction, 67

 smog, 106

National Oceanic and Atmospheric Administration 

 (NOAA)

Profiler Network, 60

Unit Citation award, 75

Nobel Prize, 4, 8, 73, 100, 102, 108 

nocturnal events, 94 

noise 

 atmospheric, 27 

 flicker, 29

 human-made, 57 

 radio, 167 

 rural, 57 

183
noise—continued

 standards, 92 

 thermometry, 49

 wideband, 16

non-methane hydrocarbons (NMHCs), 106 

nonpolar fluid mixtures, 86

normalizing blocks, 157 

North American Carbon Cycle Research Program, 

 123 

North Atlantic Ocean, 135 

North Atlantic Oscillation (NAO), 166

notched bar impact testing, 156 

n-port devices, 76

O 

oblique propagation, 27

Occupational Safety and Health Administration 

 (OSHA), 104 

ocean 

carbon dioxide sink, 123

mapped surface currents, 68 

mixed layer temperature anomalies, 140 

 observations, 8

role in drought, 172

 warming, 166 

ocean-atmosphere interaction, 135, 143 

Office of Naval Research (ONR), 71 

on-wafer transmission lines, 127 

Operational Linescan System (OLS), 152 

optical 

 clocks, see atomic clocks 

communications, wavelength standards, 161 

 fiber characterization, 91 

fiber geometry, 133

frequency "comb", 162 

pulse waveforms, 72 

remote sensing, 43

orographic precipitation, 75

orthobaric liquid density measurements, 95 

oscillators, 29

oxide barriers, 100 

oxygen, 50 

ozone 

alternative refrigerants, 134

 Antarctic depletion, 102 

depleting substances, 131

 layer protection, 7 

 production, 67

 rural, 106 

 smog, 106

P 

packet transmission, 25 

packet-switched services, 113 

paleoclimate data , 147, 154 

parahydrogen, 87 

PCS base stations, 141 

pendulum impact test, 156 

perceptual transformations , 157

perfluorocarbons (PFCs), 130

performance standards, 113 

permittivity 

international intercomparison, 56

 transmission line, 122

 water, 125 

peroxyacetyl nitrate (PAN), 106 

Peterson, Elmore, 3 

phase velocities, earth-ionosphere, 24

Philadelphia International Airport, 63

phonon coupling, 100 

photochemistry, 106 

picosecond time-domain measurements, 72 

piecewise function, 44 

piezometer, 21 

pipeline girth welds, 62 

Pitzer's acentric factor, 86 

planar near-field 

 measurements, 109 

scanning theory, 85

plane-wave 

 integral representation, 153

 spectra, 85 

plasma, ionospheric, 27, 48

Platteville, Colorado, 48

point-to-point scatter systems, 15

Poisson variable, 13

polar regions, 102 

polarization changes, 23

pollution, air, 106 

polynomials, 44 

population, 152

potential 

 difference, 58

 temperature, 126 

practical superconductors, 65, 90

precipitation, 75

prediction 

climate change, 128 

communication system behavior, 167 

communication systems, 32 

 drought, 172

HF ionospheric propagation, 27

liquefied natural gas densities, 95

long-term median transmission loss, 36 

 transmission loss, 28 

 viscosity, 86 

pressure vessels, 104 

probe calibration, 55

Program for Regional Observing and Forecasting 

 Systems (PROFS), 7 

propagation 

acoustic waves, 115 

184
propagation—continued

constant measurement, 127 

effects of cloud droplets, 125 

ground waves, 82 

 irregular terrain, 46

long distance, 26 

 meteors, 25 

millimeter-wave propagation model (MPM), 112

 modeling, 15 

 oblique, 27

radio wave system loss, 15

 theory, 22 

properties 

 cryogens, 83 

 hydrogen, 87

 materials, 97 

 natural gas, 151 

 thin films, 129 

propulsion systems, 50 

pseudo-Brewster angle, 26

public safety, 141 

pulse measurements, 71 

pulse tube refrigerators, 101 

pulsed laser, 31

PVT (pressure-density-temperature), 21, 86 

PWSM theory, 85

Q 

quality factor (Q), 153, 170

Quality of Service (QoS), 113

quantum 

 computing, 142

 superposition theory, 144

quartz oscillators, 19, 29

quasiparticle tunneling, 108

qubits (quantum bits), 142 

R 

radar 

acoustic, 37, 43

 aircraft safety, 63 

clear air Doppler, 115 

Colorado wind-profiling network, 98

 depolarization, 163 

mesoscale analysis, 75 

ocean surface currents mapping, 68 

UWB signal effects, 165 

 VHF, 60

radiated power, 170 

radiation 

hazard monitoring, 81 

 pressure cooling, 73

Radio Acoustic Sounding System (RASS), 115 

radio 

communications, 27, 33

 frequency

 atmospheric refractive index, 10 

 spectrum efficiency, 28 

 horizon, 11

 noise

 high-frequency atmospheric, 167 

 human-made, 57 

 paths, 28 

 propagation 

 ITS/Longley-Rice model, 88

 meteor trail reflection, 25

 prediction, 28

 receivers, 141 

refractive index of air, 32

 signal attenuation, 88

 spectrum, 165 

 system

 design, 36

 satisfactory service requirements, 28 

 transmission, 25 

 waves

 attenuation, 46 

 high-frequency, 27

 long , 26

 lower atmosphere propagation, 32

 meteor interaction, 25

 phase measurements, 11

 scattering, 11

 system loss propagation, 15 

 versus acoustic, 37

 VLF, 24

Radio Laboratory Section, 2 

Radio Propagation Executive Council, 2 

Radio Spectrum Measurement System (RSMS), 7 

radiographs, 62

radiosondes, 115 

Rapid Update Cycle (RUC), 7, 126 

rawinsondes, 60, 126 

reaction rates, chlorofluorocarbons, 67 

received signals, 25 

receivers, 141 

receiving systems, 69 

reduced test times, 170

reemergence mechanism, 140 

reference plane position, 122

refineries, 104

reflection 

height propagation characteristics , 26

 meteor trails, 25

reflectometers, 64 

reflectors, moon, 6 

refraction, ionospheric radio waves, 23

refractivity, air, 10, 32

refrigerants (chlorofluorocarbons), 131, 134

185
refrigerators 

 cryogenic, 71

 dilution, 34

 pulse tube, 101

Refrigerant Properties (REFPROP) database, 134

Reichsanstalt method, 21

relative ionospheric opacity meter, see riometer 

remote sensing 

 acoustic, 43

 cloud droplets, 125 

millimeter-wave propagation model (MPM), 112

Radio Acoustic Sounding System, 115 

residential noise, 57

residue series, 82 

resistor electrical noise, 49 

resonant absorbers, 73 

reverberation chambers, 153 

Reynolds, Vergyl H., 2 

RF interference, 16

riometer, 16 

Roberts, Walter Orr, 2 

S 

Shelkunoff, S.A., Award, 109

Satellite Home Viewer Improvement Act, 36

scanning 

 confocal microscope, 133 

 electron microscopy (SEM), 132 

scattering, permittivity determination, 122

scattering-matrix theory, 85

Schrödinger cat, 144

scintillations, ionospheric, 23 

sea surface temperature (SST) 

deep mixed layer anomalies, 140 

ENSO teleconnection phases, 149 

North Atlantic climate change, 166 

sea surface temperature (SST) 

North Atlantic Ocean anomalies, 135 

optimal anomaly growth, 143

role in droughts, 172

second definition (time), 6

sensing applications, 165

service system models, 74 

severe storms, 7, see also Big Thompson,

mesoanalysis 

shadow region, 26

Shirley, Jon H., 7

short dipole probes, 81

short-term forecasts, 126

short-waves (meteorology), 94 

Siegwarth, Jim, 7 

signal detection, 69

sinks, carbon dioxide, 123 

six-port 

 reflectometers, 64 

 systems, 76 

slush hydrogen, 6 

small curvature approximation, 82 

smog, 67, 106

smooth curve fitting, 44

sodars, 37

software defined radio (SDR), 141 

solar 

 flares, 16 

 irradiance, 147 

solid materials, themal conductivity, 54

solidification models, 145

Solomon, Susan, 8 

source-sink distributions, 123

Space Age, 27 

space applications, 101 

Space Disturbance Forecast Center, 6 

Space Environmental Forecasting Division, 6 

Space Shuttle Columbia, 8 

S-parameters, 127 

spearhead echo, 63 

specific heat of fluids, 21 

spectroscopy, 111 

spectrum 

 efficiency, 28 

 management, 165 

speech quality, 157

speed of light, 52, 93 

stable linear dynamical system, 143 

stainless steel, 84, 114, 136 

Standard Reference Materials 

 # 2520, 133 

 wavelength standards, 161 

Stapleton International Airport (Denver), 63

statistics 

atomic frequency standards, 29

immunity and emission measurements, 153

stochastic forcing, 143 

storm damage, 63 

Storm Prediction Center (SPC), 126 

storms, upper atmosphere, 138

stratified media, 22

stratosphere 

 chlorofluorocarbons, see chlorofluorocarbons 

ice clouds, 102 

 ozone layer, see ozone 

wind profiling radar, 60

stress, superconducting wires, 66 

submarines, 26 

sunlight 

geomagnetic storms, 138 

smog production, 67, 106 

Sunset radar, 7, 60

186
superconducting 

 amplifier, 49

devices, small, 71

energy gap, 108 

 measurement standard, 90 

 wires, 66

Superconducting Quantum Interference Device 

 (SQUID), 47

superconductors 

alternating-field susceptometry, 124

critical current, 90 

 practical, 65 

 tunneling spectroscopy, 100

supercurrents, 110 

superposition theory, 144

surface 

 currents, ocean, 68 

 impedance, 82

surface-level ozone, 106, see also ozone 

susceptometry, 124 

switched telecommunication networks, 74

synchronization, time, 116 

synoptic time scale, 32

system loss, 15 

T 

Table of Allotments, 36 

Tech Note 101 (NBS), 15, 28, 36 

telecommunications 

 Allan variance, 29

atmospheric radio waves, 33

human-made radio noise, 57

performance measurement, 13 

teleconnections, 149

telephone networks, 74

television relay, 15

TEM, see transverse electromagnetic 

temperature measurements 

Arctic warming, 147 

Radio Acoustic Sounding System, 115 

Terminal Doppler Weather Radar, 63 

terrain, see irregular terrain 

thermal conductivity, 54, 107 

Thermal-energy associative-detachment reactions, 33 

thermistor detectors, 76

thermoacoustic refrigerators, 101

thermocline, 140

thermometers, 49, 146 

thermophysical properties, oxygen, 50 

thermosphere, 138 

Thévenin's equivalent circuit, 81 

thin films, 129 

Thru-reflect-line (TRL)

 calibration, 127

 method, 76

Thru-Short-Delay (TSD), 76

thunderstorms, 94, see also convection, severe 

 storms, mesoscale convective complexes 

time

 measurements, 29 

 synchronization, 116 

trace gases 

Arctic climate change, 147 

 methane, 128 

 smog, 106

Trans-Alaska pipeline, 62 

transhorizon communications, 11

transmission 

 lines 

 impedance standards, 76

 on-wafer, 127 

 permittivity, 122

 loss 

 concept development, 15 

 tropospheric communication circuits, 28 

 paths, 11 

Transmission/Reflection Method, 122

transmitted speech quality, 157

transmitters, ultrawideband, 165

transport critical-current, 110 

transverse electromagnetic (TEM) cells, 55 

trapped surface waves, 82 

traveling-wave antennas, 59

tropics 

convective systems, 94 

El Niño Southern Oscillation phases, 149

North Atlantic climate effects, 166 

role in droughts, 172 

sea surface temperature growth, 143 

troposcatter, 11, 15

troposphere 

acoustic remote sensing, 37

 communication circuits, 28 

radio propagation, 15 

radio transmission loss, 36

remote sensing, 42

stratified media models, 22

 winds, 60, 98

Tropospheric Propagation Section (CRPL), 11

tropospheric scatter, see troposcatter 

Truman, Harry S., 2 

tunnel junction measurements, 100

tunneling spectroscopy, 100, 108

turbulence, atmospheric, 11 

TvTime, 6 

U 

U.S. Capitol Dome, 8 

ultra high frequency fields, 11

ultrawideband (UWB), 8, 165

unintentional emitter, 170

Union Oil Company, 104

187
universal quantum logic gate, 142 wideband

Universal Time (UT), 138 model, 167 

University of Colorado (CU), 5, 6 noise, 16 

urban sprawl, 152 Wieman, Carl, 8 

USAF Air Weather Service, 6 wind 

user behavior, network congestion, 74 damage footprints, 63

geomagnetic storms, 138 

V monsoonal, 169 

 neutral, 53 

very high frequency (VHF) profilers 

Colorado wind-profiling network, 98 buoy-mounted, 8 

 ionospheric soundings, 5 Colorado wind-profiling network, 98

stratified media models, 22 high-energy pulsed Doppler lidar, 7 

 troposcatter, 11 Mesoscale Analysis and Prediction System, 126 

wind profiling radar, 60 Space Shuttle Columbia, 8 

very low frequency (VLF) Sunset VHF radar, 7, 60

 ionospheric soundings, 5 Wind Profiler Demonstration Network, 115 

long distance propagation, 26 shear, 63 radio wave propagation, 24 winter season stratified media models, 22 El Niño Southern Oscillation events, 149 Video Quality Metric (VQM), 8, 171 ice shapes in clouds, 163 virial coefficients, 107 North Atlantic climate variations, 135 visible radiance, 152

ocean mixed layer anomalies, 140 volcanic activity, 147 wireless systems, 165 voltage World Data Center (WDC), 5 deviation, 167 World Trade Center, 8 measurement, 99 World War II Interservice Radio Propagation 

 Laboratory (IRPL), 27 W WR10 thermal noise, 92

Wullenweber antenna, 59 W.R.G. Baker Award, 109 

warm core system (meteorology), 94 X 

wave hop theory, 26 

Wave Propagation Lab, 60 X.25/X.75 Protocols, 113 

waveform model, 167 X-band, 12 wavelength-division-multiplexed (WDM) optical x-ray communications systems, 161 detection, 146 

weak links, high-temperature superconductors, 110 diffraction, 145 Weather Bureau, 6, see also National Weather Service 

welding Y 

austenitic stainless steels, 84

 ferrite content, 114 Yagi-Uda antennas, 59 pipeline girth, 62 Yeager, James J., 3 repair, 104 

structures at cryogenic temperatures, 136 

White House, 6 

white-light interference microscope, 133 

188