bluuebunny/crossref_metadata_2025 huggingface dataset:
Radio interferometry
Authors: Robertson Douglas S.
Published: February 2008

The potential of Very Long Baseline Interferometry (VLBI) to provide important new geodetic, geophysical, and astrometric information has long been recognized, and the past four years have seen a realization of that potential. VLBI measurements have been used to determine the sizes, shapes, rotations, flexures and tectonic deformations of networks of observing stations and have attained a level of accuracy and stability that is unmatched by any other observing technique. The surge of new data taken during this period has improved our understanding of the interactions between the Earth's mantle and its fluid core and atmosphere, improved our knowledge of lithospheric deformation, improved the determination of the Earth tide Love numbers, set a new standard of accuracy for the determination of variations in the Earth's orientation, and improved our knowledge of the celestial reference coordinate frame which is of fundamental importance for determining the motions of the Earth.
The rotation of the Earth
Authors: King Robert W.
Published: February 2008

Studies of the earth's rotation provide one of the best means of probing the interactions of the atmosphere, oceans, and solid earth as well as the structure of the core and mantle. Since the last report of the U.S. National Report to the IUGG [Tapley, 1983], two developments have led to significant improvement in the measurement of the rotation: the upgrading of the laser network of the National Aeronautics and Space Administration (NASA), and the expansion of VLBI observations coordinated by the National Geodetic Survey (NGS), with the support of NASA and the U. S. Naval Observatory. Both of these developments have been complemented by strong contributions from other countries. The availability of more accurate measurements, together with healthy research support in this field by federal agencies, has also created a ripe environment for progress in theoretical studies of the rotation.
New instrumentation techniques in geodesy
Authors: Jekeli Christopher
Published: February 2008

A review of new instrumentation techniques in geodesy shows a steady strive towards rapid, automated data collection that reduces costs, but maintains accuracy. The geodetic application potential of the Global Positioning System is well on its way to being fully developed.
Historic and paleomagnetic secular variation and the Earth's core dynamo process
Authors: Lund Steve P. , Olson Peter
Published: February 2008

This paper attempts to summarize briefly the recent and ongoing efforts of the geomagnetism and paleomagnetism community to understand both the earth's magnetic‐field secular variation, and its implications for the core dynamo process. Secular variation is defined in this paper as the general spatio‐temporal variation of the field; secular change will refer to the first time derivative of the spatial field (strict geomagnetic definition of secular variation). We will emphasize here the long‐term (10¹ year or longer) behavior of the historic secular variation (HSV), for this is the variation that is comparable with the paleomagnetic secular variation (PSV). Two important related topics, the 1969/1970 geomagnetic ‘jerk’ in secular acceleration and the spatial geomagnetic field components due to crustal or mantle sources, are treated more fully in other reviews.
Magnetostratigraphy: In pursuit of missing links
Authors: Tauxe L. , Butler R. , Herguera J. C.
Published: February 2008

Since the last quadrennial report, magneto‐stratigraphy has continued to flourish. The primary issues have been (1) refinements to the geomagnetic reversal time scale (GRTS) including recalibrations, correlation of biostratigraphic data to the CRTS and revision of the terminology, (2) use of magnetostratigraphic data for estimating rates of such processes as sediment accumulation, evolution and faunal migration, and (3) magnetic mineralogy and the origin of remanence. For convenience, we have divided the publications into studies of continental and marine sediments and highlight the most exciting issues within each of these sub‐headings. In the first section of this review, we will concentrate on the development of the geomagnetic reversal time scale (GRTS), with particular emphasis on refinements from the last few years. We then turn our attention to applications of magnetostratigraphy in marine and continental sequences.
Application of paleomagnetism to accretionary tectonics and structural geology
Authors: Hillhouse John W. , McWilliams Michael O.
Published: February 2008

The use of paleomagnetism to determine translations and rotations of geologic terranes has contributed to a better understanding of deformation within accretionary complexes, shear zones, and rifts. In this report to the I.U.G.G., we review the progress resulting from paleomagnetic studies during the last four years in the Cordillera of North America, the Appalachian orogen, and the circum‐Pacific region.
Volcanology, geochemistry, and petrology 1983–1986
Authors: Longhi John
Published: February 2008

Reginald A. Daly was remarkably prescient when he chose the title Igneous Rocks And The Depths Of The Earth for his classic book, for this title could properly serve with minor qualification as an alternative title of the Volcanology, Geochemistry, and Petrology (VGP) section of the 1983–1986 IUGG Quadrennial Report. Igneous rocks, their minerals, and their associated volatiles continue to be the major focus of research aimed at describing and deciphering compositional variation at all scales within the earth from the mantle to magma chambers to lava flows. Even where igneous rocks and processes are not the primary focus of research, such as in studies of ore deposits and metamorphic terrains, igneous activity is frequently invoked to supply metals and/or heat. Not surprisingly, then, this section of the Quadrennial Report is weighted heavily towards igneous rocks and processes. As is the case with each of the reports of the subsections, this comprehensive overview regretably, but necessarily, falls short of completeness.
Thermodynamics of minerals and melts
Authors: Ghiorso Mark S.
Published: February 2008

This is a rather exciting time to be reviewing the topic of the thermodynamics of minerals and melts. The subject is in a state of flux. The reasons for this are both conceptual and technical and arise from the fact that the disciplines of geochemistry and petrology have now matured to recognize that equilibrium thermodynamics is inadequate for describing the mechanism of a geochemical process. To appreciate these details requires irreversible thermodynamics, or better still kinetics, and in most cases some consideration of the fluid dynamics of the system under study. These subjects build upon equilibrium thermodynamics in that adequate descriptions of the energetics of geochemical processes depend on knowing the extent to which the system deviates from the equilibrium state. In a sense this realization marks the dawning of the age of chemical affinity. To apply kinetics to geologic systems one needs excellent standard state thermodyanmic data, comprehensive solution models and large scale computational ability. Technically, research on the thermodynamics of minerals and melts has advanced (perhaps unwittingly) to meet this need in that we have seen over the last five years (1) an order‐of‐magnitude increase in the quantity and quality of thermodynamic data for silicate melts and glasses, (2) the use of spectroscopic methods to infer structural properties and thereby allow the construction of models for configurational entropies of melts and solids, and (3) the use of sophisticated computational algorithms to model multicomponent phase equilibria and extract sets of consistent thermodynamic data for geologic systems. The conceptual advances in this field have been just as revolutionary. Quantum and statistical mechanics now play their appropriate fundamental role in the description of the thermodynamic properties of geologic materials. Though we are far from the ability to predict the equation of state of a complex mineral or melt solution, it is now possible to say a great deal about the theoretical functional form of expressions describing the energetics of mixing. Let us hope this marks the close of the age of Margules parameters!
Seismology of the continental crust and upper mantle
Authors: Mooney Walter D.
Published: February 2008

More seismological studies of the continental crust and sub‐crustal lithosphere of the United States have been completed in the past four years than at any other similar period, and a continued growth in activity is likely to continue for years to come. Several trends account for this phenomenon. First, the interest in seismic reflection studies generated initially by COCORP results in this country [Brown and others, 1986], and later by the British BIRPS results [Matthews and Gheadie, 1986], has led to the development of several other seismic reflection programs. Among the most active of these research programs are those of the University of Wyoming [Smithson and others, 1986], Virginia Polytechnic Institute, CALCRUST [Henyey, 1986], and the U.S. Geological Survey (USGS) [Hamilton, 1986]. In Canada, the Lithoprobe program has achieved remarkable results in a variety of geographic locations [Green et al., 1986]. A second trend is the resurgence of interest in seismic‐refraction/wide‐angle reflection profiling. The year 1978 marked the beginning of this increased activity when several large projects were conducted in the western U.S., such as the Yellowstone‐Snake River Plain experiment organized by the University of Utah. Since 1979, a large amount of refraction/wide‐angle reflection data has been collected by the USGS and by university groups utilizing large numbers of state‐of‐the‐art industry seismographs in cooperative experiments. A third trend is the increased sophistication of other seismic methods such as teleseismic delay‐time methods, tomography, and receiver‐transfer functions. In these studies, permanent or temporary recording arrays have been used to determine local and regional crustal and upper‐mantle structure with impressive resolution.
IRIS—A university consortium for seismology
Authors: Smith Stewart W.
Published: February 2008

IRIS is a university consortium organized to provide modernized seismographic networks and data distribution facilities for the university research community and funded by the National Science Foundation (NSF). There are currently 50 member institutions, each of which is represented on the Board of Directors. Overall policy and scientific guidance is provided by this Board acting through a 7‐member Executive Committee and three 9‐member Standing Committees representing each of the program elements. Technical and management support is provided by the President, and a Program Manager or Director for the three operational programs which are 1) Global Seismographic Network (GSN), 2) Portable Array Studies (PASSCAL), and 3) Data Management Center (DMC). This paper presents the historical background of development of IRIS and a review of current operational programs.
Thermal state of the lithosphere
Authors: Furlong Kevin P. , Chapman David S.
Published: February 2008

Thermal aspects of geological processes play a central role in tectonophysics. The thermal state of the lithosphere also has a bearing on studies in other earth science disciplines such as seismology, petrology, geochemistry and volcanology. In this report we attempt to emphasize these interrelationships, within a framework of plate tectonic and other geodynamic processes. This review first addresses thermal processes at plate margins, including processes at spreading ridges and rifts, transform faults, and plate convergence zones. Thermal processes in plate interiors are discussed next; this encompasses largely epeirogenic vertical movements that result in basin formation arid plateau uplift, and in thermal rejuvenation by hot spots. Finally, the thermal state and evolution of both oceanic and continental lithosphere is followed for different periods in earth history. Heat flow observations are described in terms of the constraints they provide for the respective large scale thermal processes.
Mineral and melt physics
Authors: Bass Jay D.
Published: February 2008

The previous four years have been a period of enormous discovery, growth and diversification in the mineral physics community. To underscore this point, several highlights of the U.S. research effort can be listed from a wide range of fields. Relatively young experimental methods have quickly matured and come to produce exceedingly important results; a prime example of this is the measurement of the elastic moduli of the β and γ high‐pressure phases of forsterite by Brillouin spectroscopy [Weidner et al., 1984; Sawamoto et al., 1984]. The technical capabilities of more established techniques have been considerably extended, with a spectacular example being provided by the attainment of a statically‐ maintained pressure of 550 GPa (5.5 Mbar) using a diamond anvil cell [Xu et. al, 1986]; this pressure far exceeds that in the center of the Earth! Moreover, existing static and dynamic high pressure technologies have been utilized in new and creative ways. A wide variety of spectroscopic methods are being used not only to measure the properties of materials, but also to precisely define the temperature and pressure conditions which are achieved within the small sample volume of a diamond anvil cell. The determinations of the melting points of Fe to 43 GPa [Boehler, 1986] and Mg.9Fe.1SiO3‐perovskite to 60 GPa [Jeanloz and Heinz, 1984] are but two examples of how the diamond cell is being used to perform quantitative phase equilibrium measurements at ultrahigh pressures. Additional constraints on the phase relations of high‐pressure silicates are being provided by calorimetric measurements of thermochemical properties [e.g., Akaogi et al., 1984]. Complementary to these efforts are dynamic measurements of the sound velocity [Brown and McQueen, 1986] and temperature [Lyzenga et al., 1983] during shock wave experiments. Both of these variables are sensitive to phase transitions and have been used to constrain the phase diagrams of Fe and SiO2, respectively, at pressures ranging to hundreds of GPa. Another new application of shock wave methods has been in the measurement of the pressure‐density equation‐of‐state of silicate melts [Rigden et al., 1984], which gives experimental support to the interesting possibility of melts sinking, rather than rising, at depth in the mantle. Parallel to these experimental advances have been a series of theoretical efforts to model the equation‐of‐ state and stability of high‐pressure phases. First‐principles calculations were recently performed to investigate the high‐pressure equation‐of‐state of oxides [Hemley et al., 1985; Bukowinski, 1985], as well as structurally complex high‐pressure silicates such as perovskites [Wolf and Bukowinski, 1986], and are in broad agreement with available experimental data on crystal structures and physical properties.
Plates and their motions
Authors: Jurdy Donna M.
Published: February 2008

The last reviews which covered research in plate motions were those of Herron and Pitman [1975] on marine magnetic anomalies and Dewey [1975] on plate tectonics, both reporting on research for the period 1971–1974. In the last 12 years there has been considerable refinement of relative motion models, as well as further development of global models. Also, major effort has gone into defining reference frames for the study of plate motions, and discriminating between them. More recently, the role of errors in individual plate rotations and the associated uncertainties in reconstructions have received attention. In this report I concentrate on work published in the last 4 years, 1983–1986, citing a minimum of publications from previous years; however, some papers in press for early 1987 have been included. This report first reviews work on relative plate motions for the present and past, and reconstructions, and then models for these motions, global ones for driving forces and local ones determining subduction history and back‐arc spreading. The problem of reference frames, both hotspot and paleomagnetic, is discussed next. I end with a review of work on the errors in plate motions.
Dissolved gases in seawater and sediments
Authors: Key R. M.
Published: February 2008

Certainly the most controversial results derived from the study of any dissolved gas concerned oxygen utilization rates in the North Atlantic. Jenkins (1982) estimated a net oxy‐gen utilization rate (OUR) for the Beta triangle region of the North Atlantic (apices 26.5°N x 38.5°W, 32.5°N x 30.0°W, and 22.5°N x 28.5°W) of 5.7 moles of oxygen consumed m−2 yr−1 for the zone below 100m. He assumed that the oxygen distribution below the euphotic zone was stationary and steady state and therfore that the in situ oxygen consumption must be balanced by physical transport of oxygen into the area. His estimates were based on measured distributions of dissolved oxygen and the tracers 3He and 3H and a simple model which assumed lateral advection was small. The derived value or OUR was several times higher that previous estimates based on 14C and 15N incubation techniques. The OUR requires a downward flux of carbon from the photic zone of approximately 50 gCm−2yr−1 , which is again much higher that previous results. Jenkins and Goldman (1985) amplified the arguments in a study of seasonal oxygen cycling and primary production based on a ten year time series of measurements from the Panulirus station near Bermuda. Considering insolation, heat budgets and 3He/3H data they estimated a vertically integrated oxygen production rate of 5 Mm−2yr−1 and a subsequent new production of 50 gCm−2yr−1. The results were supported by calculations based on a second order turbulence closure model (Klein and Coste, 1984). These results have been challenged primarily on the basis of the spatial variability of the phenomenon!. Whatever the final outcome Jenkins has clearly demonstrated that the time has come to take a fresh look at oxygen utilization rates and primary productivity given the tools and modelling capabilities now at hand. The TTO data set will go a long way toward providing the necessary data set for the North Atlantic when the analyses are complete. Other studies have dealt with the photooxidative daylight loss of oxygen from near‐surface tropical waters (Gieskes and Kraay, 1982), isotopic fractionation between fresh and seawater and the atmosphere (Benson and Krause, 1984) , edge effects on chemistry in the 02 minimum zone (Mullins et al., 1985), and the relationship between oxygen and other biogeochemical properties (Pak, 1984; Blizard and Pak, 1984; Lewitus and Broenkow, 1985).
Review of marine organic geochemistry
Authors: Farrington John W.
Published: February 2008

Publication of this review will occur within a few months of the tenth anniversary of the volume, Concepts in Marine Organic Chemistry (Anderson, 1977). That volume reviewed the topic up to that time and provided a prognosis and stimulus for a strong program of research in marine organic geochemistry for the past ten years. The previous United States report to IUGG on this topic (Gagosian, 1983) provided an excellent review of the literature of 1979–1982 and focused in an informative manner on several specific subtopics. This review adopts the same organization format, although some of the subtopics are new and some previous subtopics are not emphasized because of the marine organic geochemical research and the new divisions within the United States report on Chemical Oceanography and Paleooceanography.
Chemistry of seafloor hydrothermal systems
Authors: McDuff Russell E.
Published: February 2008

The past four years saw advances in a number of aspects of hydrothermal chemistry. High temperature venting was documented at a number of sites, in association with the spectrum of seafloor volcanic activity: slow to fast spreading normal ridges, seamounts, back arc settings; sediment‐hosted and sediment‐starved sites. Significant progress was made in the description, both theoretical and observational, of the geometry of circulation and the nature of water‐rock reaction. Hydrothermal plumes received extensive study, expanding the range of documented anomalies and demonstrating more clearly the links to hydrothermal sedimentation. Biological‐chemical interactions began to be explored in a quantitative way. Pore fluid advection on sedimented ridge flanks was characterized at a number of sites, though the general question of the importance of off‐axis basalt‐seawater interaction remains unresolved.
Introduction to Paleointensity Articles
Authors: Merrill Ronald T. , Heirtzler J. R.
Published: February 2008

After indicating the basis of the technique, its use with a cryogenic SQUID magnetometer is outlined, particular emphasis being given to the need for stringent reliability criteria. Comparison of results for some samples is made with results obtained using the Shaw alternating‐field technique, and the agreement is satisfactory. Determinations made on 14 samples fired during the last 150 years give results which on average are in close agreement (within 2%) with observatory‐based values, the standard deviation of a sample from the predicted value being ±6%.
Energetic particles and currents: Results from Dynamics Explorer
Authors: Burch J. L.
Published: February 2008

The suprathermal plasma instruments on DE 1 and DE 2 (high‐altitude plasma instrument, low‐altitude plasma instrument, and energetic ion composition spectrometer) have provided new data on the distribution functions and composition of plasmas at altitudes from a few hundred to ∼23,000 km. Of particular interest are the results that have been obtained on the injection and transport of plasma in the polar cusp, on the upward acceleration of ionospheric ions and electrons, and on the charge carriers of the various high‐latitude Birkeland current systems (using independent measurements of the currents by the magnetic field instruments MAG‐A and MAG‐B). These results and other contributions of the Dynamics Explorer hot plasma and magnetic field measurements to our understanding of magnetosphere‐ionosphere coupling are reviewed in this paper.
Closing remarks to “Magma genesis, plate tectonics, and chemical differentiation of the Earth” by Peter J. Wyllie
Authors: Lal D.
Published: February 2008

Among several things, Professor Wyllie has emphasized the influence of volatile components in many magmatic processes. This underscores the importance of understanding interrelationships among the solid and fluid layers of the Earth for at least two reasons. First, our understanding of the magmatic processes is a prerequisite to understanding the evolution of the Earth's atmosphere. Second, the flux of CO2 and other volatiles from volcanoes may have been significant in the geological past and may have led to geological discontinuities. The K‐T boundary has been assigned to this cause by some.
URSI: The International Scientific Radio Union
Authors: Silver Samuel
Published: February 2008

The International Scientific Radio Union,1 better known as URSI (an abbreviation derived from the French name, Union Radio Scientifique Internationale), is one of the oldest of the family of scientific unions comprising the International Council of Scientific Unions (ICSU). The Union was founded in 1913 under the title ‘International Commission of Scientific Wireless Telegraphy,’ and it celebrated its golden jubilee in 1963 in conjunction with a general assembly held in Tokyo. The history of the Union, and the development of its commissions, and programs, and worldwide services, was recorded in the URSI Golden Jubilee Memorial volume published by the URSI Secretariat in 1963. The aims of the Union as stated by the late J. H. Dellinger in his history of the URSI in the Jubilee Memorial are2:

1. To promote international cooperation in the scientific study of radio.

2. To encourage and aid in the organization of radio research requiring cooperation on a large scale.

3. To promote the establishment and use of common methods and standards of measurement.

4. To encourage and aid the discussion and dissemination of the results of these activities.
The United States National Committee of URSI
Authors: Morgan Millett G.
Published: February 2008

The community of radio scientists in the United States participates in URSI through a committee of the Division of Physical Sciences of the National Research Council. The Research Council was organized in 1916 by the National Academy of Sciences at the request of President Wilson to enable the broad community of scientists and engineers in the country to associate its efforts with those of the more limited membership of the Academy in service to science and the nation. Members of the Research Council and its committees, boards, and panels are drawn from governmental, academic, industrial, and other institutions and organizations throughout the country. The Research Council is supported by private and public contributions, grants, and contracts, and by voluntary contributions of time and effort by several thousand of the nation's leading scientists and engineers.
A Comparative Study of Several Models of the Magnetoplasma
Authors: Akkaya Inci
Published: February 2008

In this paper, an unbounded, collision‐free magnetoplasma of one species is analyzed by applying linearized theory. Modifications on the cold plasma dispersion surfaces due to the temperature effect are indicated by typical examples. To take into account the particle‐wave interactions, a microscopic model of the magnetoplasma is analyzed for very large refractive indices and for very high temperatures. Two directions of propagation (along and across the biasing magnetic field Bº) are considered, According to the results of the microscopic model, at gyroresonance for propagation along Bº the complex refractive index n cannot have arbitrarily large values if its phase angle is between −π/4, and π/4, whereas, for propagation across Bº, η becomes real and arbitrarily large. Both of these results contradict those of the compressible fluid model.
Shot Noise in Antennas
Authors: de Pazzis O.
Published: February 2008

The noise received by an antenna immersed in a hot plasma is directly related to the input resistance of the antenna as computed by Kuehl (1966), using a Maxwellian velocity distribution. The result is rederived for a plasma with any stable velocity distribution.
Effect of the Earth's Albedo on the Ionospheric D Layer
Authors: Gassmann G. J. , Wagner R. A.
Published: February 2008

An aircraft carrying an ionospheric sounder traversed the boundaries of extended cloud cover near Los Angeles five times on July 18, 1967. Amplitudes of ionospheric E‐layer echoes at 3 MHz were received and recorded on magnetic tape, and median values were determined in 1‐minute intervals. Although these values scattered over ±3 decibels, the average median was lower, by 2.1 decibels, when the aircraft was over cloud cover than when the aircraft was over a cloud‐free area. The results suggest that an enhancement of the flux of visible light due to the reflecting cloud cover (estimated albedo 40%) changed the D‐layer chemistry in such a way that the electron density increased, resulting in a (6±3)% increase of two‐way non‐deviative absorption.
Foreword
Authors: Waterman A. T.
Published: February 2008

The material in this document has been prepared by various members of Commissions to the U.S. National Committee of URSI. It represents a highly condensed account of progress within the general field of each Commission during the past three years.

Every three years URSI holds a General Assembly in which the member countries report to each other the advances that have been made. The material contained here represents the report of the United States to this international body. The subject matter is arranged in accordance with the commission structure of URSI. These Commissions, eight in number, are 1, Radio Standards and Measurements; 2, Radio and Non‐ionized Media; 3, On the Ionosphere; 4, On the Magnetosphere; 5, Radio Astronomy; 6, Radio Waves and Circuits; 7, Radio Electronics; and 8, Radio Noise of Terrestrial Origin.
Commission 6: Progress in Radio Waves and Transmission of Information: 2. Information Theory, Circuit Theory, and Computer‐Aided Design
Authors: Van Valkenburg M. E. , Thomas J. B. , Kuh E. S. , Calahan D. A.
Published: February 2008

As in previous summaries, the words ‘information theory’ are used in the wide sense to include such areas as (1) statistical communication theory, (2) detection theory, (3) pattern recognition and adaptive systems, (4) coding theory, and similar examples of the interaction of random processes and communication systems. For classification purposes, progress in information theory will be described under the four headings just listed.
The Near Field of the Loop Antenna
Authors: Fante R. L. , Otazo J. J. , Mayhan J. T.
Published: February 2008

The near fields of a circular loop antenna have been evaluated and discussed for various size loops. The results are obtained in a form that is useful in predicting the microwave breakdown characteristics of the antenna.
Irregularities in the Equatorial E Region Over Thumba
Authors: Prakash Satya , Gupta S. P. , Subbaraya B. H.
Published: February 2008

A rocket‐borne Langmuir probe and plasma‐noise probe have been used to study the ionization irregularities of scale sizes 20 meters to 0.4 meter in the lower equatorial ionosphere over Thumba during the evening twilight of February 2, 1968. lonization irregularities were observed mostly in the height range 97–106 km, 142–155 km and around 170 km. The spectral index n was calculated for a power law of the type E(k) = Akn. In the 100‐km region, irregularities with different spectral indices were found to coexist, indicating the superposition of at least two different spectra. The irregularities with spectral index of −3.0 to −3.5 are probably produced through neutral turbulence, whereas irregularities with spectral index of −1.6 to −2.0 are probably produced by electric fields. The irregularities observed near the rocket apogee are produced by the rocket itself and have a spectral index of +3.0. The actual values of these indices are likely to be more (including sign) than given by the present calculations since the detection efficiency of a Langmuir probe for the irregularities may be size‐dependent.
Faraday Rotation of the 136 MHz Transmission From the Geostationary Satellite ‘Canary Bird’ Observed at Nairobi
Authors: Hunter A. N.
Published: February 2008

The 136 MHz transmissions from 'Canary Bird' were recorded at Nairobi, 1.32°S, 36.8°E, 26°(dip) from June 1967 through February 1968. The receiving system used a Yagi aerial rotating 1 rev in 6 sec. Plots of diurnal variation of Faraday rotation are given for the months of July, October, November, and December 1967 and January and February 1968. These plots show general agreement with the mean diurnal variation of total electron content as determined from the traveling satellite BE‐B. One important feature which is much more marked in the geostationary satellite records is a large increase in total electron content at about 2300 hours; at this time there is commonly a marked lowering of ionosphere height. This peak, which is also apparent in foF2, is thought to be associated with movement of the equatorial anomaly maxima.
Heating of the Ionosphere and Attenuation of the Equatorial Hydromagnetic Waves
Authors: Dubs C. W. , Prasad B. , Sen H. K.
Published: February 2008

Effects of the velocity dependence of collision cross sections (momentum and energy transfer in a 3‐component ionospheric gas) on the transversely propagated hydromagnetic waves at the equator are studied. The ordinary mode is found to be profoundly affected, but the extraordinary mode is not. These effects should be important in estimating joule heat including mode‐mode coupling and reflections in a vertically stratified ionosphere. It is also shown that the space‐charge electric field due to neutral wind drag in the dynamo region of the ionosphere provides adequate energy to the electrons to compensate for their cooling by inelastic collisions with neutral molecules.
Response of the 1000‐Kilometer Ionosphere to Magnetic Storms
Authors: Reddy B. M. , Lakshmi D. R. , Brace L. H.
Published: February 2008

Measurements of electron concentration and electron temperatures by the Langmuir probe experiment of the Explorer 22 satellite during 1966 are employed to study the response of the topside ionosphere, at 1000 km, to magnetic storms. The analysis was limited to the American longitudes (50° to 130°W) over a latitude range from 50°S to 70°N geomagnetic. The daytime response is characterized by various degrees of electron‐density enhancements over the entire latitude range, with the winter high latitudes undergoing highest enhancement. The electron‐temperature changes are not so unique. An attempt is made to explain some of these features qualitatively, based on thermal expansion of the upper atmosphere during storms and the ‘viscous drag’ of the solar plasma on the magnetosphere.
Long and Short Period Changes in Magnetic Activity at Huancayo During the Solar Cycle
Authors: Chernosky Edwin J.
Published: February 2008

Forty years of geomagnetic activity data at Huancayo are evaluated in two periodicities: the hourly and the daily changes of the horizontal magnetic field intensity. Monthly means of both periodicities are affected similarly by solar activity in that they both show the characteristic semiannual variation. Although the amplitudes of the hourly changes follow solar activity changes closely, the daily changes show a ‘bite out’ near sunspot maximum when annual means of each are compared. The ‘bite out’ may be due to the occurrence of magnetic storm depressions of a different duration at that time. The results suggest that the slower magnetic variations at the dip equator should not be studied as a single manifestation but in periodicity bands, as micropulsations are studied.
Atmosphere of Venus as Studied with the Mariner 5 Dual Radio‐Frequency Occultation Experiment
Authors: Fjeldbo G. , Eshleman V. R.
Published: February 2008

The amplitudes and differential Doppler of two radio signals transmitted to Mariner 5 as it was occulted by Venus are utilized to derive the dayside and nightside ionization distributions in the upper atmosphere, and the temperature and pressure profiles of the lower atmosphere. Both sides of Venus have ionization peaks near the 140‐km altitude level; the daytime peak is 30 times greater in electron number density. The nightside ionosphere extended up to an altitude of at least 1000 km, and the dayside ionization terminated in a plasmapause near an altitude of 500 km. There may be a wake of planetary ionization extending a great distance in the antisolar direction. The neutral atmosphere was probed down to within 35 km of the planetary surface. Differences in the temperature and pressure profiles for the nightside and dayside, and apparent kilometer‐size structure in the atmosphere, are discussed.
Refractivity of Carbon Dioxide Under Simulated Martian Conditions
Authors: Tyler G. Leonard , Howard H. Taylor
Published: February 2008

The refractivity of carbon dioxide has been measured at 2.26 GHz under simulated Martian conditions and at standard temperature and pressure. In the temperature range of 150° to 190°K, at pressures from 2 to 25 millibars, the refractivity per molecule per cm2 is 1.78 × 10−17 ± 0.06 when scaled by the ideal gas law. The measurements include pressures and temperatures which are within 30°C of the sublimation curve. This result is slightly lower than the best measurements previously obtained near standard temperature and pressure at other frequencies (1.8345 × 10−17 ± 0.0003) and at 2.26 GHz under standard conditions by the authors (1.8413 × 10−17 ± 0.005). It is concluded that the scaled refractivity of CO2 in the range of temperatures and pressures stated above may be a few percent lower than under standard conditions. These results do not significantly alter the conclusions regarding the atmosphere of Mars as measured by the radio occultation method.
Microstructure of Temperature Fields in the Free Atmosphere
Authors: Tsvang L. R.
Published: February 2008

The data on the variation of the structure characteristics of the temperature field CT2 in the free atmosphere have been obtained at heights from 50 to 4000 meters. The aircraft instrument measurements were made in summer during the day and night and under different synoptic conditions above the steppe and the sea. It has been shown that under the condition of a developed convection, CT2 decreases with the height as Z−4/3. For other conditions an averaged dependence of CT2 on height was obtained. For the case of a stable stratification, the dependence of CT2 on the gradient of the potential temperature is shown. Cumulus cloudiness exerts a strong influence on the height variation of CT2. Above the sea CT2 changes little either day or night. At night above the steppe, however, CT2 increases with height.
Homogeneity of the Tropospheric Refractive‐Index Structure
Authors: Børresen Jan A. , Gjessing Dag T.
Published: February 2008

By the aid of beam‐swinging experiments, information regarding the spatial homogeneity of the refractive‐index field in the height interval from 1.0 to 8.0 km was obtained.The troposphere was found to be highly homogeneous in the horizontal direction, whereas in the vertical direction the rate at which the spectral density Φ decreased with height z was considerable (mean value of 7db/km). Correlating the received power with all the pertinent meteorological parameters that can be deduced from radiosonde measurements, we found a correlation coefficient of 0.91 with the refractive index N. By correlating dΦ/dz with the spatial mean values of the meteorological parameters, a significant relationship was found with a composite expression that includes the refractive index, the static stability, and the wind shear.
Spectra of Internal Waves and Turbulence in Stratified Fluids: 1. General Discussion and Indications from Measurements in Stably Stratified Atmosphere and Ocean
Authors: Pao Yih‐Ho
Published: February 2008

A unified spectral description of internal waves and turbulence in a stably stratified atmosphere or ocean is proposed. We envisage that the fluctuating motions in a free atmosphere with scales smaller than the synoptic scale consist of internal waves and turbulence. At low wavenumbers, internal waves predominate; this range of wavenumbers may be called the internal wave subrange. The internal waves can be identified from the characteristics of velocity‐scalar cospectra and quadrature spectra, as shown recently by Pao [1969b] in a laboratory experiment. When the internal waves are sufficiently strong and distinct, the different harmonics of internal waves may appear in the autospectra of velocity and temperature where the peaks and valleys are clearly identifiable. This, we believe, explains the presence of peaks and valleys in some velocity autospectra of clear air turbulence measured in strongly stratified regions of the atmosphere. At intermediate wavenumbers (buoyant subrange) the buoyancy effect is still strong but the turbulent scrambling process also becomes important; the higher‐order harmonics of internal waves are no longer distinct and cannot be detected in the autospectra; the velocity autospectra are steeper than k−5/3. At high wavenumbers (inertial and viscous subranges) turbulence predominates. The characteristics of fluctuating motion in this range of wavenumbers can be described well with Kolmogorov's concept of local isotropy and are not affected by the stratification. The proposed spectral behavior for the free atmosphere is described in detail and supported with existing measurements in stably stratified regions of the atmosphere and ocean in part 1. It will be further supported by our laboratory experiments on the breaking of internal waves in a two‐fluid system [Hall and Pao, 1969] in part 2.
Spectra of Internal Waves and Turbulence in Stratified Fluids: 2. Experiments on the Breaking of Internal Waves in a Two‐Fluid System
Authors: Hall J. Michael , Pao Yih‐Ho
Published: February 2008

The breaking of internal waves on a sloping surface in a two‐fluid system is studied experimentally in a wave tank. The characteristics of breaking internal waves are examined through their frequency spectra for cases of different frequency, amplitude, and wavelength. Waveheight measurements are made with capacitance probes in conjunction with a recently developed capacitance bridge and are processed by computer utilizing the Cooley‐Tukey fast Fourier transform algorithm. By using a direct, on‐line computer system spectra can be computed with a high degree of accuracy and a very narrow bandwidth. Spectra measured in the breaking region of the tank reveal a series of sharp peaks in the low frequency range representing the different harmonics of the internal waves. These higher modes, which possess little or no energy in the incident wave, gain energy at the expense of the lowest mode as the wave train propagates over the sloping surface. The result is a transfer of energy to higher frequencies through growth of the harmonics, each mode gaining energy at the expense of lower modes and transferring it to higher modes. At higher frequencies the spectra no longer possess these distinct harmonics. The high frequency end of the spectrum in the breaking region has a slope of approximately −3 for all cases considered.
Electric Dipole Radiation in the Presence of a Moving, Dispersive Dielectric Half‐Space
Authors: Holmes J. Fred , Ishimaru Akira
Published: February 2008

The problem of a point electric dipole moving over a dispersive dielectric half‐space is studied. The dipole is located in the free space above the dielectric and is assumed to be time harmonic in its rest frame, oriented perpendicular to the interface, and moving parallel to it. Solutions for this problem are obtained by using integral transform techniques. Expressions for the electric and magnetic fields in the free space region are formulated for the reflected radiation field for the case of an arbitrary, dispersive dielectric and for the lateral wave and surface wave fields for the case of a lossless plasma dielectric. In the rest frame of the source, it is found that all three waves exhibit the frequency of the source and that the field patterns are distorted by the relative motion. In the rest frame of the dielectric, it is found that each of the waves exhibits some form of Doppler shift (different from the primary wave) and that their field patterns are also distorted. It is also found that the criterion for existence of the lateral wave is not modified by the relative motion of the source and dielectric but that the criterion for existence of the surface waves is greatly modified by the relative motion. In addition, for velocities greater than some critical velocity, it is found that a new type of surface wave comes into existence.
Transient Wave Reflection From Inhomogeneous Plasmas
Authors: Sodha M. S. , Chakravarti A. K.
Published: February 2008

Distortion of an electromagnetic pulse undergoing total internal reflection in inhomogeneous isotropic plasmas with special reference to the lower ionosphere has been investigated. The initial transient response and buildup of the reflected signal for different angles of incidence has been numerically investigated. It is seen that the signal builds up more rapidly for larger angles of incidence, and the dispersion is maximum for normal incidence of the pulse. This observation is in qualitative agreement with the experimental observations of Schmitt (1965) for uniform plasmas.
Photometry and Polarimetry of the Lunar Regolith as Measured by Surveyor
Authors: Holt Henry E.
Published: February 2008

Photometric and polarimetric properties of lunar soil and rock fragments were determined from Surveyor pictures. High resolution measurements (centimeter scale) revealed differences in the photometric functions of various materials concomitant with probable different fine‐scale surface textures. The photometric function of the light, undisturbed fine‐grained lunar soil is similar to the function measured through an earth‐based telescope (kilometer resolution), whereas the darker, disturbed soil has a more peaked backscatter function, and smooth compressed soil has more Lambertian‐like reflectivity. Most rock fragments seem to have essentially dust‐free surfaces and a Lambertian‐like photometric function; their normal albedos are estimated to range from 9 to 22%.

The polarimetric function of lunar soil is similar to that of basalt and gabbro powdered to a grain size of 30 to 75 μ. Lunar rocks reflecting strongly polarized light (up to 34% polarized) have the highest albedos. The observed polarimetric function of lunar rocks is more similar to that of basalt and gabbro than any other common rock type.
Composition of the Moon From Balloon‐Borne Mid‐Infrared Observations
Authors: Salisbury John W.
Published: February 2008

Mid‐infrared spectra (7.0 to 13.5 μ) of six different areas on the lunar surface have been obtained from an altitude of 31 km by using a 24‐inch balloon‐borne telescope. All spectra show significant departures from blackbody or graybody emission, in particular displaying a peak in emissivity that varies in wavelength from 8.11 to 8.37 μ. The position of this peak varies regularly with type of surface feature in the field of view. Laboratory studies show that the wavelength of peak emissivity in surface emission can be interpreted in terms of rock composition, and that the differences in peak emissivity from place to place result from differences in rock type. Barring some unanticipated systematic error, the data obtained so far indicate that the two circular maria, Imbrium and Serenitatis, are ultrabasic in composition, whereas the lunar crust appears to be basic in composition. This compositional heterogeneity may explain location of major mascons in the circular maria.
Estimation of Local Lunar Gravity Features
Authors: Gottlieb Peter
Published: February 2008

A quantitative estimate of the gravity features on the near surface of the moon has been obtained by iteratively constructing a mass density model to improve the agreement between actual Doppler tracking data from Lunar‐Orbiter spacecraft and theoretical trajectory predictions. Thirty three typical orbits (24 nearly polar and 9 nearly equatorial) were selected at 3 to 4 degree separations to cover most of the front side of the moon. Each iterative stage consisted of placing masses near the lunar surface at locations indicated by the peak residual accelerations observed after fitting the data with the model constructed at the previous iteration.
A Synchrotron Model for the Decimetric Rradiation of Jupiter
Authors: Clarke J. N.
Published: February 2008

The two‐dimensional distribution of intensity and polarization has been calculated for the synchrotron radiation from electrons trapped in a dipolar magnetic field around a planet. From formulas recently published by Legg and Westfold, the circular polarization is included. The integrated data from these maps are used to suggest models with two thick belts of electrons to account for the decimetric radiation from Jupiter.
A Radiometer Employing Frequency‐Domain Coding
Authors: Aitken G. J. M. , Mills R. J.
Published: February 2008

A radiometer has been developed in which the spectrum of the noise‐like signal is shaped (spectral coding) so that it can be distinguished from the receiver noise by a simple correlation process. This radiometer has a small‐signal sensitivity comparable to that of the Dicke (temporally coded) system and an output insensitive to variations in the system gain or front‐end temperature. An advantage of the system is the simplicity of the required hardware, leading to the possibility of high reliability. A practical radiometer was constructed to demonstrate the technique.