bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and fabrication considerations for construction of monolithic, hybrid optical components for optical computing applications
Authors: Wakelin Suzanne , Derstine Matthew W.
Published: February 2023

Development of robust and reliable optical systems is essential in order to utilize the connectivity and parallelism of optics in conjunction with electronics in smart pixel information processors. Bulk optical imaging systems utilizing custom and off-the-shelf optics and optomechanics can provide some solutions to optical interconnections in laboratory experiments and system demonstrations. However, there are optical and size limitations to classical imaging techniques that can be overcome with the use of hybrid bulk and micro optic imaging. Use of large arrays of microlenses is an effective method of interconnecting large dilute arrays of smart pixels. The micro channel technique for 4-f imaging of focal spot arrays and device planes establishes a single optical path for each channel in the array. This type of one-to-one imaging may be usefully implemented in various imaging systems. In addition to simple one to one imaging, arrays of focal spots originating from different sources must be combined together. For example, signal inputs incident a smart pixel array must be combined with the clock array that is used to read the state of the devices. We have investigated bulk and microoptic components and subsystems to be applied to optical computing applications. This has involved study of the practical and theoretical performances of the various components. The progression of our work in implementing free-space smart pixel imaging systems establishes the techniques that will utilize micro optical components in practical system subassemblies.
Cascadable thyristor optoelectronic switch operating at 50 Mbit/sec with 7.2 femtoJoule external optical input energy
Authors: Heremans Paul , Knüpfer Bernhard , Kuijk Maarten , Vounckx Roger , Borghs Gustaaf
Published: February 2023

Most optoelectronic switches are characterized by a trade-off between the optical input sensitivity, the operation frequency and the area on chip. Fast operation usually occurs at the expense of sensitivity, or else requires considerable chip area for fast amplification in several stages of the input signal. It has recently been shown that specially designed optical thyristors, called depleted thyristors, are not subject to this trade-off [1], The thyristor layer structure must be conceived such that the device can be depleted of carriers by a negative anode-to-cathode voltage pulse. Such structure has intrinsically high speed capabilities, which can be combined with extreme optical input sensitivity by using differential pairs of thyristors instead of single thyristors [2]. The differential pair (Fig. 1) consists of two thyristors A and B connected in parallel, which have a common series resistance Rc [3]. When thyristor A is on and thyristor B is off, the differential switch is in the "1" state; with A off and B on the switch is in the "0" state. The thyristor in the on-state emits light. This allows cascaded operation using the same type of optical thyristor pair both for the emitting and the receiving side of optical interconnects, or for optical computing.
Demonstration of a Laterally Inhibitive Optical Preprocessor Using Quantum Well Fabry-Perot Modulators
Authors: Kelly Brian , Hegarty John , Horan Paul , Tooley Frank , Taghizadeh Mohammad
Published: February 2023

Laterally inhibitive connections form a basic component of many neural network algorithms. This paper describes a self-linearised inhibitory test system (SLITS) to demonstrate basic image manipulation using arrays of quantum well (QW) modulators. Inhibition between neighbouring nodes is utilised to perform edge contrast enhancement [1]. System interconnections are both optical and electrical with non-local interconnections being made optically using diffractive elements and a one-to-one electronic connection providing the inhibitory response.
Limitations of optical lateral intraconnection of smart pixel arrays
Authors: Kakizaki Sunao , Horan Paul
Published: February 2023

Many early vision and image processing algorithms are characterised by relatively simple processing, dependent on a weighted sum of pixels within a specified surrounding neighbourhood. Many algorithms, as shown schematically in fig. 1a involve a summation over some neighbourhood of radius r where the output depends only on the inputs. Serial processing of such algorithms can be efficiently implemented using pipelined architectures.
Hybrid Electro-Optic Resonator for Image Classification
Authors: Weverka Robert T. , Wagner Kelvin
Published: February 2023

Optical resonators are a powerful tool for object classification. Using a volume hologram to store and simultaneously probe thousands of reference images, they can take an input image and find the best matched reference object from a vast stored library. Developments in this field are proceeding rapidly in numerous laboratories1-3. These research efforts are confined, however, to all-optical resonator systems which suffer from the speed and gain limitations of photorefractives, and from the lack of shift invariance of the inner-product function performed when the input image is used to read a volume hologram.
Detection- and Estimation-Theoretic Accuracy Enhancement in Discrete Analog Optical Processors
Authors: Timuçin Doğan A. , Walkup John F. , Krile Thomas F.
Published: February 2023

We recently presented a rigorous statistical analysis of a generic three-plane optical processor whose architecture is common to a number of information-processing systems including optical correlators, optical interconnects, and optical linear algebra processors [1, 2].
High Accurate Optical Analog Computing Implemented on Optical Fractal Synthesizer
Authors: Tanida Jun , Watanabe Wataru , Ichioka Yoshiki
Published: February 2023

In the course of exploring capabilities of optical computing, optical analog scheme is important field to be researched more actively. Optical analog computing has excellent advantages, i.e., large data capacity, large processing capability, flexibility in data representation, and so on. Various optical transforms such as conventional and fractional Fourier transforms and optical techniques including vector-matrix multiplier and matched filter are good examples of the field.
Volume Holographic Storage and Retrieval of Digital Information
Authors: Hesselink Lambertus , Heanue John F. , Bashaw Matt C.
Published: February 2023

We discuss the experimental performance of a digital holographic data storage device and architectural and materials issues related to achieving large capacity and low bit error rates.
Sparse-Wavelength Angularly Multiplexed Volume Holographic Memory
Authors: Campbell Scott , Yi Xianmin , Yeh Pochi
Published: February 2023

Photorefractive-based optical memory systems have received considerable attention in recent years [1-6] In these systems, numerous volume holograms are stored within a single photorefractive crystal, with the writing and recall selectivity generally being performed via angle [1] wavelength [2,3], or phase [4] multiplexing. As well, non-photorefractive-based optical memory systems [7,8] have been proposed. In this paper, we present a hybrid system [6] that utilizes a combination of wavelength and angle multiplexing in a photorefractive medium. Such a hybridization is driven by photonic source generation and manipulation device limitations, as well as the desire to expand information throughput rates in optical memory systems via spectral parallelism [9]. Our design is essentially the summation over wavelength of many angularly multiplexed volume memory systems. We therefore compare our system’s parameters to those of purely wavelength or angle multiplexed ones.
All-Optical Parallel-to-Serial Conversion by Holographic Spatial-to-Temporal Frequency Encoding
Authors: Sun Pang-chen , Mazurenko Yuri T. , Fainman Yeshayahu
Published: February 2023

The bandwidth and the efficiency of fiber optic communication systems exceed these of electrical cable systems. However, presently, we are far from realizing the potential performance of optical networks. Electronic devices and systems connected to optical networks may reach bit-rates on the order of 1 Gb/s. In contrast, the maximum bit-rate of a photonic network may exceed 1 Tb/s, limited by the performance of the optical fiber. The three order-of-magnitude mismatch between fiber and device capacity can be used to increase the speed, security, and reliability in the data transmission. Several all-optical methods exploiting this bit-rate mismatch are being investigated for controlling data streams in communication channels to utilize this bandwidth more efficiently. These approaches may include mutual conversion of the space-to-time, space-to-frequency, spatial frequency-to-time and spatial frequency-to-temporal frequency. The possibility of converting optical image or image-like parallel data into the optical fiber has been demonstrated by using a pair of moving gratings to introduce spatial-to-temporal encoding1. In this manuscript we introduce a holographic method that allows parallel-to-serial (i.e., space-to- time) optical signal conversion by encoding spatial frequency spectrum of the parallel optical signals onto the temporal frequency spectrum of optical pulses. Moreover, by combining our technique with existing serial-to-parallel conversion methods2,3 we demonstrate the possibility of transmitting parallel optical signals over long distance optical fiber network.
Applications of Laser-Induced Breakdown Spectroscopy
Authors: Radziemski Leon J.
Published: February 2023

The focusing of a modestly energetic pulsed laser beam (E ≳ 10 mJ) can lead to a breakdown plasma which may be used for qualitative and quantitative spectrochemistry. Although the precision of the method is poorer than that of conventional spectrochemical techniques, the method has distinct advantage in certain circumstances. (1) The plasma can be generated without electrodes, hence non-invasive (but destructive) analysis is possible in hostile environments. (2) Being an emission technique, simultaneous multi-element analysis is possible. (3) The plasma can be made almost arbitrarily small, allowing microanalysis of samples. (4) In contrast to common laser microprobe techniques, auxiliary analysis is not required, simplifying the instrument package and reducing the cost. (5) A variety of sample forms can be interrogated, conducting or nonconducting solids, as well as liquids and gases. (6) Preparative chemistry of the sample is not required, allowing truly real-time analysis. The latter fact is a two-edged sword. Real samples are often inhomogeneous, and their sampling leads to reduced precision. The method is limited to elemental analysis, because the plasma dissociates molecules. In general the precision of the results is not high, although detection limits can be quite good, as indicated below. The applications for this technique will not be those amenable to conventional laboratory spectro-chemistry, they will be the ingenious ideas of the frustrated analyst. The review given here cannot be all-inclusive. I have chosen examples which indicate the breadth of applications, and obviously ones with which I am familiar. The early history of laser plasma spectrochemistry is reviewed by Laqua (1).
Remote Measurements of Methane in Underground Mines
Authors: Litton Charles D.
Published: February 2023

Methane is a natural by-product in the formation of coal and is present, in varying quantities, in all underground coal mines. The presence of methane presents an imminent hazard since it can mix with air to form explosive gas mixtures (5 to 15% methane in air mixtures are flammable) which can devastate an entire mine if ignited.
Atmosphere Temperature Profile Sounder
Authors: Mochang Wang
Published: February 2023

This paper describes narrow band filters, DLATGS infrared detector and electronic processing technique in the Atmosphere Temperature Profile Sounder (ATPS) and presents its main performance in the primary calibration.
Determination of Spectral Properties of the Earth Radiation Budget at Selected Sites
Authors: Whitlock C. H. , Suttles J. T. , Barkstrom B. R. , LeCroy S. R.
Published: February 2023

The Earth Radiation Budget Experiment (ERBE) satellite system is concerned with the measurement of total radiation both entering and leaving the Earth-atmosphere system. In order to improve scientific understanding of radiation phenomena, optical experiments are being conducted in support of the satellite measurements to better determine both stratospheric and tropospheric components for specific atmospheric and surface albedo conditions. Such data may also be used to validate various radiative transfer models which are used to analyze data from other satellite systems. This paper describes the combination of radiometric and lidar measurements as well as analytical procedures which are used for spectral characterization of both downwelling and upwelling radiation in stratified atmospheres. Results are given from the first in the series of experiments.
Errors in ground based water vapor Dial measurements due to Doppler broadened Rayleigh backscattering
Authors: Ansmann A.
Published: February 2023

The line shape of backscattered laser power is Doppler broadened by backscattering of air molecules. This paper presents a theoretical analysis of the influence of Doppler broadening of the Rayleigh backscattered laser line on the measurement of the water vapor density
N(R¯) in the atmospheric layer at
R¯=(R1+R2)/2 with thickness dR = R2– R1using the Dial approximation where
σ1(R¯) is the calculated on line absorption cross section and Pijwith i=1: on line, i=2: off line and j=1, 2 are the detected lidar signals for R1anti R2. In order to determine these effects quantitatively, results of simulation studies are presented.
Stratospheric Monitoring Using a Balloon-Borne Tunable Diode Laser Spectrometer
Authors: Webster C. R. , Menzies R. T.
Published: February 2023

The Balloon-borne Laser In-Situ Sensor (BLISS) instrument is a microprocessor controlled high-resolution absorption spectrometer operating in the mid-infrared wavelength region.1 Tunable lead-salt diode lasers provide infrared radiation in selected wavelength regions for sensitive derivative absorption spectroscopy over a 1-km round-trip path. The TDL radiation is directed to a retroreflector which is lowered up to 500 m below the instrument gondola. A HeNe laser and co-aligned TV camera with CID imaging are used for retroreflector tracking. The instrument operates with three TDLs, and the capability exits to measure five stratospheric species simultaneously: NO, NO2, HNO3, O3, and H2O. A selected TDL is frequency-modulated at 2 kHz and scanned in wavelength over a spectral feature of the species of interest. An onboard cell filled with a fraction of a torr of the gas to be monitored is used to obtain a reference spectrum, for line identification and wavelength calibration. The returned signal from the lowered retroreflector is demodulated so that the 4-kHz second-derivative signal may be compared with the total returned power which is simultaneously measured by a low-frequency chop/demodulation. From a knowledge of the linestrength, lineshape, stratospheric temperature and pressure, the modulation/ demodulation parameters, and the pathlength used, the mixing ratio of the species may be extracted from the measured absorptance.
Lidar Sensing of Air-Sea Exchange
Authors: Atlas David , Walter Bernard
Published: February 2023

This paper describes the structure and mechanisms of the convective roll vortices seen by airborne lidar scattering from sea salt aerosols and measured directly by instruments on another aircraft. The observations were taken off the east coast during a cold air outbreak. In addition, we discuss the ways in which the lidar may be used to estimate some of the key parameters related to the surface heat flux. Much of what follows is based upon the work of Chou and Atlas, 1982; Melfi et al, 1984; and Atlas, 1985.
Infrared Limb Scanning - Technique and Results
Authors: Gille John C.
Published: February 2023

The main features of limb scanning derive directly from the view geometry. The thermal radiation emitted by a gas along the tangential path through the atmosphere is seen against the cold background of space. These factors enhance the sensitivity to the emission of trace gases, and allow weak features to be seen up to altitudes limited only by the noise level of the instrument and the uncertainty of the background determination. Emission spectra of the atmosphere show features of the "major" (ppmv) trace species--CO2, O3, H2O, CH4 and N2O as well as species present only in ppbv amounts--HNOg and NOg, with interference from gases present in even smaller concentrations.
A Slant Path Method for Measurement of Atmospheric Transmittance and Backscatter by CO2 Lidar
Authors: Winker D.M.
Published: February 2023

A CO2 lidar system using a tunable CO2 TEA laser has been developed to measure aerosol backscatter and atmospheric transmittance in the 8-12μm window region. The system operates at 1 Hz with a pulse energy of several joules when operated in the line-tuned mode. The transmitter and receiver are coaxial and a large plane mirror placed in front of the receiver is used to scan the beams in elevation, allowing slant path returns to be acquired. A photoconductive HgCdTe detector is used in the direct detection mode restricting the operating range of the system to the mixing layer, where aerosol concentrations are high.
Visibility Related to Backscatter at 1.06 UM
Authors: Barber T. L. , Larson D. R.
Published: February 2023

At those locations, such as airports, where measurements of visibility are critical to operational safety and efficiency, an infrared lidar may be used to provide high spatial resolution along selectable paths. Lidar measurements of backscatter at these infrared wavelengths may be converted to visibility through those relationships such as those developed in this paper.
The Pressure Modulator Infrared Radiometer: A Remote Sounder for the Atmosphere of Mars
Authors: McCleese D. J. , Schofield J. T.
Published: February 2023

In this paper we describe the Pressure Modulator Infrared Radiometer (PMIRR); a candidate atmospheric sounder for the forthcoming Mars Geoscience/Climatology Observer mission (MGCO). The PMIRR employs pressure modulation gas correlation spectroscopy and narrow band filter radiometry in the 7-50 μm spectral range in both limb-scanning and nadir sounding modes to obtain simultaneous vertical profiles of temperature, water vapor, dust and condensates in the atmosphere of Mars. The PMIRR instrument concept builds upon a substantial heritage of flight-proven hardware used on Earth and Venus orbiting spacecraft.
SCIDAR/Lidar Description of a Gravity Wave and Associated Turbulence - Preliminary Results
Authors: Vernin J. , Pelon J.
Published: February 2023

SCIDAR is an acronym for SCIintillation Detection And Ranging. This new optical sounder allows remote sensing of the atmospheric turbulence from an altitude of 1km up to 20-30km. The basic principle of this turbulence profiler is the statistical analysis of the speckle pattern produced by the light coming from a double star [1].
GASCOFIL: A Gas Correlation Filter Spectrometer for Remote Sensing of Trace Atmospheric Constituents
Authors: Morrow W.H. , Nicholls R.W.
Published: February 2023

A new gas filter correlation spectrometer, GASCOFIL, that can be used to sense scattered UV or visible sky light or thermal infrared emission has been developed and field tested. The instrument includes a microprocessor based data acquisition and signal processing system. GASCOFIL is a rugged portable field application instrument for measurment of column densities of specific molecular atmospheric pollutants. It simultaneously measures the irradiance in a narrow spectral bypass and the cross correlation of the irradiance spectrum with gas cell spectra for features in the bandpass of the system. The bandpass is adjustable from 0.14 to 9.5 microns by the selection of appropriate interference filters and detectors.
LIDAR Atmospheric Measurements at AFGL
Authors: Sipler D.P. , Philbrick C.R. , Dix B.E. , Gardner M.E.
Published: February 2023

A two color Lidar is used at AFGL to make temperature, density and aerosol measurements in the 20-45 km range. Highly variable aerosol concentrations have been found around 25 km.
Reliability of airborne CO2 DIAL measurements: Schemes for testing technical performance and reducing interference from differential reflectance
Authors: Wiesemann Wolf , Lehmann Frank
Published: February 2023

Airborne remote sensing systems using the earth's surface as a reflector are suffering from the differential reflectance properties of the topographic targets. For example, the errors associated with ozone monitoring in the thermal infrared can reach up to 70 ppb.km 1). This paper proposes a scheme which can reduce this margin remarkably, however, on the penalty of increased technical complexity.
Airborne Lidar Tracking of Fluorescent Tracers for Atmospheric Transport and Diffusion Studies
Authors: Uthe Edward E. , Viezee William , Ching Jason K.S.
Published: February 2023

Development and validation of transport models for the study of regional acid deposition require improved observations of pollutant transport and dispersion processes for various atmospheric conditions. No suitable method for air-parcel tracking along non-constant density surfaces is available. Following a technique described by Rowland and Konrad (1979), SRI International has demonstrated the feasibility of using an airborne lidar system to observe atmospheric transport and dispersion of fluorescent dye particle (FDP) tracers. The Airborne Lidar Plume and Haze Analyzer (ALPHA-1) constructed and operated for the Electric Power Research Institute (EPRI) was used for this purpose.
Ground Based 0.53 μm Wind Sensor
Authors: Sroga J. , Rosenberg A. , O’Hara L. , Hays P. , Kennedy B.
Published: February 2023

Laser based sensors have recently received increasing attention as systems to remotely measure basic state parameters of the atmosphere such as temperature, moisture, pressure and winds. Ground based lidar systems are currently in various stages of development to demonstrate these measurement capabilities and spaceborne lidar systems have been proposed for obtaining global coverage of data required to improve numerical weather forecasts. Measurements of the wind field have been shown to be particularly important in improving numerical forecasts (Halem, 1983).
Precipitation Identification Using Optical Scintillation of a Partially Coherent Source
Authors: Wang Ting-i , Williams D. A. , Reynolds R.R.
Published: February 2023

Techniques for identifying weather have traditionally relied on human judgement. In recent years, devices have been introduced to make automatic weather observations, but their ability to identify weather is quite limited. For example, most automatic devices can only measure the total water content of the precipitation and are unable to identify the type of precipitation such as rain, snow, or hail without the help of human observers. Recent efforts devoted to the effects of precipitation [1] on visible and infrared wave transmissions through the atmosphere suggest that optical identification of weather may provide an inexpensive and reliable method for monitoring weather conditions, making possible more complete weather sensing at automated weather stations.
The High Resolution Doppler Imager
Authors: Hays Paul B. , Skinner Wilbert R. , Abreu Vincent J. , Yee Jeng-Hwa
Published: February 2023

The High Resolution Doppler Imager (HRDI) is a triple etalon Fabry-Perot Interferometer designed to measure Doppler shifts of absorption and emission lines in the Earth's atmosphere. The instrument will be flown on board the Upper Atmosphere Research Satellite (UARS) in the early 1990's. The goal is to measure the vector winds in the stratosphere (10 to 40 km) and mesosphere and lower thermosphere (80-120 km) during the day, and the mesosphere at night to an accuracy of 5m/s. In addition to winds, the instrument will also determine temperatures, cloud top heights, and some aerosol properties. This paper briefly describes the HRDI instrument, the wind measurement concept, and the operation scenario.
The Halogen Occultation Experiment (HALOE)
Authors: Russell James M.
Published: February 2023

The catalytic destruction of ozone by components of the odd nitrogen (NOy), odd chlorine (CℓOy), and odd hydrogen (HOy) chemical families of the middle atmosphere has been a concern for many years. Key components of NOy were observed by experiments on the Nimbus 7, SAGE, and SME satellites. These data provided answers to a number of important scientific questions, but they also raised other issues which remain unanswered today. Middle atmosphere research has been further sharpened by the discovery of the springtime Antarctic ozone hole. This phenomenon 1s believed to occur because of chlorine catalyzed ozone destruction aided by heterogenous chemistry processes which are enhanced in the polar regions by the presence of polar stratospheric clouds (Solomon, 1988). Much higher levels of active chlorine are observed 1n the Antarctic winter - spring period (Solomon et al., 1987) than at lower latitudes, and consistent with this, the HCℓ to HF ratio is smaller. The Upper Atmosphere Research Satellite (UARS) complement of measurements has been designed to provide further and more comprehensive NOy and CℓOy observations over a long time period in order to address the outstanding scientific issues.
Cryogenic Limb Array Etalon Spectrometer (CLAES) Overview and System Spatial Response Calibration
Authors: Steakley Bruce C. , Roche Aidan E. , Kumer John B. , Sterritt Lanny W. , Dawson Juan C. , Reilly Charles M.
Published: February 2023

Significant attention is focused on the study of the upper atmosphere and the potential effects of changes in the climate, weather, and protection provided by the ozone layer. The NASA Upper Atmospheric Research Satellite (UARS) (figure 1) , will provide a global, continuous, and comprehensive look at the upper atmosphere over an 18 month period with scheduled launch in the fall of 1991. The Cryogenic Limb Array Etalon Spectrometer (CLAES) will derive Stratospheric temperatures and constituent number densities from the measurement of infrared spectral emissions. Overviews of the CLAES experiment and hardware are given by Roche et al (Ref 1) and Burriesci et al. (Ref 2).
Pressure and Temperature Retrievals From the SAGE III/Eos Measurements
Authors: Chu W. P. , Larsen J. C. , McCormick M. P.
Published: February 2023

The Stratospheric Aerosol and Gas Experiment III (SAGE III) instrument will be an updated version of the SAGE series of flight instruments which have successfully operated on various spacecraft platforms for remote sensing of the atmosphere utilizing the solar occultation technique. SAGE III has been selected for the definition phase study (phase A/B) for the National Polar Platform One (NPOP1) and the Space Station Attached Pay load (SSAP) of the Environmental Observatory System (Eos) Mission in the late 1990’s. The SAGE III instrument follows a long heritage of successful flight missions such as the SAM II, SAGE I, and SAGE II missions in producing global data sets of stratospheric aerosol, ozone, nitrogen dioxide, and water vapor. One of the unique characteristics of the SAGE III instrument is the ability to provide measurements of oxygen A-band absorption at the 760 nm spectral region. Oxygen A-band absorption measurements will provide independent pressure and temperature data for the retrieval of other constituents as measured by the SAGE III instrument.
A Multi-Level Tropospheric Carbon Monoxide Correlation Radiometer for Eos
Authors: Reichle Henry G.
Published: February 2023

Carbon monoxide (CO) is a key player in the chemistry of the troposphere. It is, by far, the largest sink for the hydroxyl (OH) radical, which is the oxidizer of all reduced species in the atmosphere. In addition, chemical processes involving CO produce tropospheric ozone (O3). The sources of CO are about equally divided between anthropogenic sources (combustion of fossil fuels and biomass) and natural sources (oxidation of isoprene, methane, and other hydrocarbons). Recently, increases in the mixing ratio of CO have been observed. The increasing level of CO will have direct effects on the OH level with resulting long term effects both on tropospheric ozone production and on climate through the reduced destruction of greenhouse gases like methane.
The Spectroscopy of the Atmosphere Using Far Infrared Emission Experiment (SAFIRE)
Authors: Russell James M.
Published: February 2023

It has been known for many years that the middle atmosphere (10 to 100 km) ozone distribution is controlled in part by catalytic cycles of the kind: X + O3 → X + O2 concurrent with XO + O → X + O2, giving the net result O + O3 → 2O2; i.e., a net ozone destruction. The catalyst, X, in these reactions is usually NO, OH, or Cℓ. The reactive N−, H−, and Cℓ− containing gases can be conveniently grouped into chemical families, often referred to as HOy, NOy, and CℓOy, where the main elements are H, OH, HO2, and H2O2 for HOy; N, NO, NO2, HNO3, N2O5, and HNO4 for NOy; and Cℓ, CℓO, HCℓ, HOCℓ, and CℓONO2 for CℓOy. Figure 1 is a simplified chemistry diagram showing catalytic cycles. The time scale for chemical steady state to be established within these families is generally quite short and much less than transport time scales. Thus, theoretical steady-state arguments allow the distribution within a family to be calculated. The odd hydrogen family is important throughout the atmosphere. It dominates the photochemical destruction of ozone above about 45 km, and it is also very important in the lower stratosphere (where the photochemical time scale is long). Furthermore, OH and HO2 are involved in the production and destruction of the important reservoirs HNO3, HNO4, HCℓ, and HOCℓ, which are formed by interactions between chemical families.
SAGE III
Authors: McCormick M. P.
Published: February 2023

The Stratospheric Aerosol and Gas Experiment III (SAGE III) has been selected for definition study for NASA's Polar Orbiting Platform (NPOP) and NASA's Space Station Attached Payload (SSAP). These are both part of the Agency’s Earth Observing System (Eos) for making long-term observations to understand the complex processes that affect global change. SAGE III is the latest generation of SAGE flight instruments, all of which use solar occultation to make vertical profiles of aerosols, ozone, and NO2, and to detect mid- to upper tropospheric clouds. SAGE II added, as will SAGE III, the capability to measure H2O. A description of the evolution of these experiments which began with the Stratospheric Aerosol Measurement I and II (SAM I and II) missions is given in Table 1.
The High Resolution Research Limb Sounder (HIRRLS) Instrument for Eos
Authors: Gille John C. , Bailey Paul L. , Coffey Michael T. , Mankin William G.
Published: February 2023

HIRRLS is an infrared limb-scanner for determining middle atmospheric temperature and composition with improved horizontal and vertical resolution, and enhanced capability for observing the lower stratosphere.
Deriving Upper Stratospheric Temperature from Sage II Solar Occultation Measurements
Authors: Wang Pi-Huan , McCormick M. P. , Chu W. P.
Published: February 2023

This paper highlights an experiment conducted recently at NASA Langley Research Center. The objective of this experiment is to determine the upper stratospheric temperature from the multiwavelength solar occultation measurements made by the satellite instrument of the Stratospheric Aerosol and Gas Experiment (SAGE II). To take advantage of the SAGE II solar occultation measurement, the approach of the temperature experiment involves two essential steps. The first step is to retrieve the air density information from the SAGE II measurements. The second step is the calculation of the temperature profile from the retrieved air density data. Through molecular scattering processes, the air density is one of the key components which contribute to the attenuation of the solar radiation determined by the SAGE II satellite instrument. As to the relationship between the air density and temperature distributions, they are related by the hydrostatic equation and the ideal gas law.
Inverting Lidar Data Using Realistic Atmospheric Data
Authors: Hummel John R.
Published: February 2023

Laser radars, or lidars, are powerful tools for probing the atmosphere. Inverting the lidar equation, however, suffers, from the problem of having more unknowns than equations. Numerous studies have focused on how to reduce the problem to a complete set of equations. Many of the solution schemes have major limitations as a result of the unrealistic assumptions required to complete the set of equations.
Measurements of Stratospheric Water Vapor and Ozone with the FIRS-2
Authors: Johnson D. G. , Chance K. V. , Traub W. A.
Published: February 2023

Far infrared spectra of the stratosphere contain numerous thermal emission lines which can be used to measure the abundance of a number of important molecules. We report here measurements of stratospheric H216O, H217O, H218O, HDO, and the ozone species 16O16O16O, 16O18O16O, and 18O16O16O. The data were taken during the second flight of our far infrared spectrometer (FIRS-2), May 12-13 1988, and cover the altitude range 20-50 kilometers. The largest single source of error in these measurements is the uncertainty in the line broadening parameters, which emphasizes the need for more accurate determinations of spectral line parameters.
A Tunable IR Laser Source for Remote Sensing
Authors: Cheo P. K.
Published: February 2023

Frequency tuned IR laser sources can be achieved by generating the upper and the lower sidebands from a CO2 laser using an electrooptic phase modulator. The phase modulator, which is driven by a microwave TWT amplifier in the X and Ku bands (8 to 18 GHz) can be made of either a GaAs IR waveguide with a traveling-wave microstrip transmission line (Ref. 1) or a bulk CdTe crystal filled microwave cavity operating in a resonant mode (Ref. 2). The difference between the two approaches is primarily in the achievable frequency tuning range. With a microstrip IR waveguide modulator, the frequency tuning range of 20 GHz, which is at least 20 times wider than that obtainable with a bulk crystal filled microwave cavity can be achieved. The sideband powers of comparable magnitudes (~ 2mW) can be generated by using either of the above two techniques.
Optimal performance of monostatic coherent laser radar
Authors: Frehlich R.G.
Published: February 2023

The conditions for optimal performance of monostatic coherent laser radar are discussed for various optical geometries.
Gas Filter Correlation Radiometer Concept Utilizing a Photo-Elastic Modulator
Authors: Sachse Glen W. , Wang Liang-guo
Published: February 2023

Gas filter correlation radiometers (GFCR's) have made important contributions to our knowledge of the atmosphere by providing remote atmospheric measurements from a variety of platforms including aircraft1, and spacecraft2. Though GFCR's have many attractive features including high spectral resolution, large etendu and the capability to detect many gas species, these instruments are generally mechanically complex requiring rapidly rotating gas cells or light choppers. A new GFCR concept is being investigated that uses a polarization modulator in conjunction with polarization sensitive beamsplitters as a solid-state "optical switch" to rapidly alternate the path of incoming radiation between the two GFCR optical paths (i.e., the paths containing the gas correlation and vacuum cells). Compared to more conventional GFCR's, this new approach has potential advantages including: (1) long operational life since rapidly moving mechanical parts are not required (an important consideration for spaceborne applications), and (2) a high detection frequency (≈ 100 kHz) which, for a NADIR viewing GFCR, freezes the radiometer's view of the Earth and minimizes other 1/f noise sources.
Preparing for Eos-A Demonstration of Real-Time Data Processing During the MAPS Flight, June 1992
Authors: Connors V. S. , Cahoon D. R. , Reichle H. G. , Wallio H. A. , Gormsen B. B. , Casas J. C. , Koziana J.
Published: February 2023

A real-time data assimilation and verification system will be implemented by the Measurement of Air Pollution from Satellites (MAPS) tropospheric carbon monoxide experiment during the SRL-1 space shuttle mission that is scheduled for June 1992. This complex system includes a dedicated data communication network, near real-time data processing, and a correlative measurement program.
Spectral Line Shape Considerations When Modelling Low Altitude UARS Temperature Sounding Channels
Authors: Edwards D.P.
Published: February 2023

The ability to remotely sense atmospheric quantities such as pressure, temperature and constituent gas abundance is dependent on the retrieval algorithmn used. The accuracy of this is determined in part by the way in which the ‘forward model’ calculates the atmospheric radiative transfer.
Intercomparison of Ozone Measured from the NOAA-9 and the Nimbus-7 Satellites on Short and Long Time Scales
Authors: Chandra S. , MCPeters R. D. , Hudson R. D. , Planet W.
Published: February 2023

The SBUV2 (Solar Back Scatter Ultraviolet) spectrometer on NOAA-9 has been providing global measurements of ozone in the stratosphere on a continuous basis since March 14, 1985. The SBUV2 ozone data set consisting of total ozone and ozone mixing ratio at a number of pressure levels from 30 to .3 mb, in conjunction with similar data sets obtained from the SBUV and TOMS spectrometers on NIMBUS-7 and the BUV spectrometer on NIMBUS-4, comprise one of the most comprehensive data sets on stratospheric ozone extending over two decades. These data sets are valuable resource for monitoring long term changes in the stratosphere and studying the natural and man made perturbations on time scales varying from a solar rotation to a solar cycle.
Stratospheric HO2 and OH Measurements with the FIRS-2
Authors: Traub Wesley A. , Johnson David G. , Chance Kelly V.
Published: February 2023

The FIRS-2 spectrometer system is used to make accurate measurements of many stratospheric molecular species. The experimental method is to measure mid-infrared and far-infrared thermal emission spectra of the stratosphere, from a balloon-borne platform, at a discrete number of limb elevation angles. The analysis technique is to do a least-squares fit of a theoretical spectrum (calculated from a model mixing-ratio profile) to each measured emission line spectrum.
Atmospheric Aerosol and Humidity Profiling Using an Airborne DIAL System in the Near IR
Authors: Ehret G. , Renger W.
Published: February 2023

Differential absorption Lidar (DIAL) is a powerful technique for active remote sensing of a number of atmospheric parameters and trace gases. Particularly, DIAL-systems operating in the near IR are suitable instruments for humidity profiling in the Troposphere, either from a fixed station on ground (Cahen et al., 1982) or mounted in an aircraft (Browell et al., 1984). However, airborne DIAL'S offer the possibilities to determine vertical and horizontal distributions of aerosol and water vapor in different regions and to monitor the seasonal variability and concentration. Tropospheric water vapor plays a significant role in cloud physics and climate research. The meteorological data derived from airborne DIAL measurements in the lower troposphere can be used to study growing up and stratification of the PBL. In addition, the measurements provide the opportunity to investigate aerosol and humidity interaction or to study latent heat exchange between the PBL and the free troposphere.
Spectroscopic Inferences from His Measurements of Atmospheric Thermal Emission
Authors: Revercomb H. E. , Knuteson R. O. , Smith W. L. , Woolf H. M. , Howell H. B.
Published: February 2023

Radiometrically accurate observations of the earth's emission spectrum from 3.8 to 16.6 microns have been made using the High-resolution Interferometer Sounder (HIS) to look downward from the NASA U2/ER2 aircraft or upward from the ground. These observations have been used to demonstrate the substantially improved vertical resolution of temperature and water vapor soundings derived from high resolution spectra (resolving power from 1800 to 3800), as compared to soundings from the low resolution filter radiometer observations used in current satellite sounders.
Theory and Modeling of Non-LTE Processes as Applied to Atmospheric Remote Sensing
Authors: López-Puertas M.
Published: February 2023

With the advent of higher resolution and sensitivity instruments and high precision technology, the remote sensing of the middle and upper atmosphere, especially from satellite hmb sounding, has become a reality, and nowadays it is a powerful technique to derive the temperature structure and the minor constituents abundances. It is precisely in the remote sensing of these upper regions where Non-LTE effects play a more important role because at these heights the excited states, which originate the infrared emission to be measured, start depasturing from their Boltzmann’s populations. Thus, Non-LTE effects usually impose the upper limit of the retrieval of these atmospheric parameters by remote sensing and, in other cases, the concourse of Non-LTE studies is required to correctly retrieve the atmospheric temperature and species abundances.
The Diurnal Variation of the O3(ν3) Source Functions and Limb Radiances in the Mesosphere and Lower Thermosphere
Authors: Mlynczak Martin G. , Drayson S. Roland
Published: February 2023

In order to determine ozone concentration profiles from the measurement of infrared limb emission in the 900 cm-1 to 1200 cm-1 spectral interval, an accurate knowledge of the terms composing the radiative transfer equation is required.
Climatology of Polar Stratospheric Clouds Determined From SAM II Observations
Authors: Pitts Michael C. , Poole Lamont R. , McCormick M. Patrick
Published: February 2023

The Stratospheric Aerosol Measurement (SAM) II sensor (McCormick et al., 1979), launched aboard the Nimbus 7 satellite in October 1978, is a single channel (1.0 micron) sun photometer which measures 1-km vertical resolution profiles of aerosol extinction by the solar occulation technique. Approximately 14 profiles (separated by ≈ 26° in longitude) are measured daily in each hemisphere. Due to the orbital characteristics of the Nimbus 7 satellite, the latitude of SAM II measurements varies from approximately 64° (N or S) at the solstices to approximately 80° (N or S) at the equinoxes.
Optical Properties of High Clouds [1]
Authors: Notari A. , Singh U. N. , Wilkerson T. D. , Braun W. C.
Published: February 2023

We report initial results of lidar studies of high clouds, including optically thin cirrus. This work is part of a program of middle atmosphere measurements, using the fixed site lidar at College Park and a transportable lidar built for field campaigns. This paper describes results of observations of backscatter and extinction of light at 532 nm wavelength (Nd:YAG(SHG)) by high clouds.
Recent Progress in Retrieval Methods For Remote Sounding
Authors: Rodgers Clive D.
Published: February 2023

The basic principles and concepts of retrieval theory are straightforward. The problem is to find a profile (or to characterise a class of profiles) that is consistent with remote measurements of the atmosphere, within our present understanding of the physics of the measurement. The general approach is to construct a forward model of the measurement process, and then to design a numerical method (usually iterative) which finds a profile to more or less reproduce the measurements when it is inserted in the forward model.
Comparison of Lidar and Radiosonde Measurements of Atmospheric Moisture Profiles
Authors: Melfi S. H. , Whiteman David , Ferrare Richard , Schmidlin Francis
Published: February 2023

Atmospheric water vapor represents, arguably, the most important source of heat driving atmospheric circulation. In the tropics, it is responsible for the strong convection associated with the intertropical convergence zone thus establishing the Hadley circulation and the persistent trade winds. At mid-latitudes, moisture variation with altitude can destabilize the troposphere, setting up the potential for deep convection with boundary layer moisture fueling the resultant cyclone development and intensification. Moisture also plays an important role in global warming. Its anticipated increase as a result of the doubling of carbon dioxide is expected to produce a positive feedback leading to more than 50% of the temperature increase anticipated over the next 50 years. The impact of clouds on global warming is still being studied. In addition, radio waves can be adversely affected by sharp moisture gradients in the atmosphere leading to anomalous propagation.
Lidar Sounding of Atmospheric Temperature and Density Variability with a 2.5 Meter Telescope
Authors: Dao P.D. , Meriwether J.W. , McNutt R. , Klemetti W. , Servaites J. , Moskowitz W. , Davidson G.
Published: February 2023

In May 1989 the Geophysics Laboratory (GL) mobile lidar facility was moved to Wright Patterson AFB and combined with the WRDC 2.5 meter telescope. The objective was to merge Air Force resources in a campaign to obtain atmospheric density data in the altitude range from 20 to 100 km. GL has been performing high altitude density measurements since 1984. For density measurements, the lidar system typically consists of a pulsed laser and a medium quality optical telescope to collect backscattered radiation. For UV and visible lasers, the optical signal is detected with photomultiplier tubes and the electrical signal is recorded either with a transient recorder or a multichannel scaler. The latter is used with photon counting and considerably increases the detection sensitivity.
An Interim Reference Model for the Clear-Sky Relative Humidity Between 6km and 16km Determined from SAGE II Observations
Authors: Chiou E W , McCormick M P , McMaster L R , Chu W P
Published: February 2023

Water vapor is the most important variable component of the atmosphere. It is one of the key factors shaping the weather and climate. Several major compilations of climatological water vapor distributions have now appeared in the literature (Oort , 1983; Crutcher, 1969; Newell et al., 1973). These analysis have been based largely on radiosonde measurements. Since standard radiosonde instruments do not provide reliable water vapor values above 10km, there is still very limited information on the water vapor behavior above mid troposphere.