bluuebunny/crossref_metadata_2025 huggingface dataset:
An Optical Data Filter for Selection and Projection
Authors: Mitkas P. A. , Feld S. A. , Irakliotis L. J. , Wilmsen C. W.
Published: February 2023

The management of today’s very large databases requires high storage capacity and parallel searching to ensure real-time operation. The two main characteristics of database processing are: a) most of the transactions are based on comparisons of the data fields with a search argument, and b) a large amount of data have to be retrieved and processed in order to generate the query result, which is usually a small fraction of the database. Therefore, a common solution to the problem is a special purpose processor operating as a data filter. This unit receives records from the database and screens them on the fly accordingto user defined criteria. If a record satisfies the query, it is transferred to the end user, otherwise, it is rejected.
Concepts for Fully Integrated FET SEED Circuits and their Applications for Optical Computing
Authors: Wachlowski A.J. , Tooley F.A.P. , Rhein D.
Published: February 2023

One approach to massively parallel and highly efficient information processing is to use systems containing multiple quantum well (MQW) modulators.
Massive Optical Interconnections (MOI): Interconnections for Massively Parallel Processing Systems
Authors: Araki S. , Kajita M. , Kasahara K. , Kubota K. , Kurihara K. , Redmond I. , Schenfeld E. , Suzaki T.
Published: February 2023

For many years, optics has been cited as the technology of choice for communication. In applications such as telephones, cable TV, and local area networks, it seems that optical communication has proved to have technological and economical advantages. However, in the area of parallel processing, optics has not yet made an impact, despite a number of efforts to demonstrate various concepts and principles with extensive experiments and prototyping. It seems that, so far, a conclusive opinion has not been reached. Parallel processing systems still use electronic networks for inter-processor communication.
Routing Algorithm for a Circuit-switched Optical Extended Generalized Shuffle Network
Authors: Waterson Clare , Jenkins B. Keith
Published: February 2023

Two key difficulties in the implementation and use of multistage interconnection networks have been the complexity of the network hardware and the complexity of the routing algorithm. This has been particularly evident in MIMD computing environments, when the network needs to support arbitrary interconnection pattern requests, and when no requests are to be buffered or postponed. Under the premise that the use of optics can at least partially alleviate the network hardware complexity issue, we consider in this paper the routing algorithm complexity needed to control such an optical network. We present a routing algorithm designed with the goal of minimal time complexity.
Visual Area Coding Technique (VACT) : Optical parallel implementation of fuzzy logic and visualization of its results with digital halftoning
Authors: Konishi Tsuyoshi , Tanida Jun , Ichioka Yoshiki
Published: February 2023

Optical implementation of logical operation is an important subject in digital optical computing. For example, optical array logic (OAL),1 symbolic substitution (SS),2 binary image algebra (BIA),3 and image logic algebra (ILA) 4 are typical methods for implementing optical parallel logic. Recently, optical implementation of fuzzy logic based on area-coding technique (ACT) has been proposed. 3 These methods treat image data as an information medium for parallel processing. Image has inherent features which are not only parallelism for processing but also visual interface for human. In short, the availability of visual techniques leads to the development of new approaches that are inherently visual.
A Comparison of GRIN Rod Lenses and Planar Ion-exchange Microlenses for the Interconnection of Optoelectronic Device Arrays
Authors: McArdle N. , Brenner K.-H. , Moisei J. , Kirk A. , Thienpont H.
Published: February 2023

The benefits of optical interconnections to overcome the limitations of conventional metallic connections in electronic computers are widely recognised. To demonstrate the potential of optics several systems have been constructed to interconnect optoelectronic arrays of devices. So-called "smart-pixel" devices are seen as a promising technology in future optoelectonic parallel processing systems.
Analysis of a 3-D Computer Optical Scheme with Bi-Directional Interconnects
Authors: Morozov V. , Neff J. , Fedor A. , Zhou H.J.
Published: February 2023

Computer interconnections based on optics have an advantage over electronic connections due to the ability of light to travel through space without interference with other light beams. Highly parallel computers will require highly parallel communications, and such communications cannot be supported with conventional electronic implementations because of the technological limitations of electrical interconnection in terms of area, latency, and power dissipation [1]. In Fig. 1 the conceptual design of a 3-D computer system with bi-directional interconnects is presented. This interconnection system allows for feedback of the signals within the computer system, which is an essential part of a Von Neumann machine as well as an important aspect of many algorithms, from the Fast Fourier transform to polynomial evaluation. This optoelectronic 3-D system is being pursued by the Optoelectronic Computing Systems Center (OCSC) at the University of Colorado to prove the utility and viability of 3-D computers [2].
Demonstration of a high-speed, multichannel, optical sampling oscilloscope
Authors: Morrison R. L. , Johnson S. G. , Lentine A. L. , Knox W. H.
Published: February 2023

The principle of transmitting information using free-space optics poses a serious challenge to collecting diagnostic signals within large-scale digital photonic systems1. High concentrations of parallel optical channels and localized electronic signals bring about great difficulties in monitoring high speed operations using conventional contact techniques. Up to now, the typical diagnostic procedure was to sample a portion of the light reflected from the output modulators with a system viewport and form a remote magnified image. A high-sensitivity photodetector was then sequentially aligned with each spot to transform the signal to an electronic format that could be monitored using an electronic oscilloscope. This sampling procedure and other electro-optic sampling techniques2,3 developed for high speed systems are too time consuming when many signals must be actively monitored.
Demonstration of 2-dimensional data transcription between 8x8 arrays of completely-depleted optical thyristors
Authors: Thienpont Hugo , Kirk Andrew , Veretennicoff Irina , Heremans Paul , Knupfer Bernhard , Borghs Gustaaf , Kuijk Maarten , Vounckx Roger
Published: February 2023

Differential pairs of PnpN optical thyristors are among the most promising devices for digital parallel optical information processing systems. Very recently it has been shown that these AlGaAs based detector-emitter type of devices can be cascaded at 50 MHz with only 7.2 fJ external optical input energy [1], and that this optical input energy scales with device area resulting in a record sensitivity of 15 aJ/μm2 [2]. The layer structure of these optical thyristors has been designed such that all free carriers can be extracted from the center p- and n-type layers by applying a small negative anode-to-cathode voltage pulse (complete depletion for a turn-off voltage of - 4V), while switching on the device requires a break-over voltage of 2.7 V. To be of use in practical systems the device has also been engineered to be cascadable. In this way, an optical thyristor operating as a detector is sensitive to the light that an identical element, working as an emitter, generates. Moreover, a differential pair configuration has been adopted to increase the optical input sensitivity [3]. Finally, correct operation of 8*8 monolithic arrays (see Fig la) of these completely depleted, cascadable differential pairs has been demonstrated [4].
Analysis of Parasitic Front-end Capacitance and Thermal Resistance in Hybrid Flip-chip-bonded GaAs SEED/Si CMOS Receivers
Authors: Novotny R.A. , Lentine A.L. , Buchholz D.B. , Krishnamoorthy A.V.
Published: February 2023

Smart pixels[1] consisting of photodetectors, electronic circuitry, and E/O converters utilizing free-space optical interconnections show promise to relieve the interconnection bottleneck in computing and switching systems.[2] To reduce the propagation delay through a smart pixel, the receiver requires a fast response, hence it is essential to reduce the front end capacitance (Cin). Cin has three main components: the photodiode active area, the amplifier input, and the stray interconnect capacitance (Cs). The FET-SEED technology minimizes Cs through the monolithic integration of photodetectors, modulators and electronic circuitry.[3][4]] However, current system demonstrations using FET-SEEDs have been limited to using medium scale integration (MSI) smart pixel arrays. Hybrid integration of VLSI Si CMOS electronic circuitry with photodetectors, modulators, or emitters is an attractive approach in obtaining VLSI smart pixels in the near term.
Optical information processing by synthesis of the coherence function -Real-time processing by using real-time holography-
Authors: Okugawa T. , Hotate K.
Published: February 2023

We have proposed and studied the synthesis of the optical coherence function by utilizing direct frequency modulation of a laser diode[1-4]. We applied this manner to 2-dimensional (2-D) or 3-D optical information processing systems[3,4]. It has the optical processing functions, such as a slice extraction of an arbitrary depth from a 3-D semitransparent object. In this information processing system, holography is used to choose the interference component selectively from other components. Use of a silver-halide hologram has prevented real-time processing in our previous study[3,4]. In this presentation, we demonstrate real-time processing by using a liquid crystal spatial light modulator as a real-time hologram.
Adaptive Beam-Steering and Jammer-Nulling Photorefractive Phased-Array Radar Processor
Authors: Sarto Anthony W. , Weverka Robert T. , Wagner Kelvin
Published: February 2023

We are developing a class of optical phased-array-radar processors which use the large number of degrees-of-freedom (DOF) available in three-dimensional photorefractive volume holograms to time integrate the adaptive weights in order to perform beam-steering and jammer-cancellation signal-processing tasks for very large phased-array antennas[1,2]. For a large broadband phased-array antenna containing 1000s of array elements, beam steering and jammer cancellation in a dynamic signal environment represents an extremely demanding signal processing task well beyond the capabilities of microelectronic digital signal processing because of the large number of DOF required for adaptation. The three-dimensional nature of the signal environment (2 angle-of-arrival and frequency) represents a signal processing problem which maps well into a highly parallel optical processing architecture utilizing photorefractive volume holograms. The beam-steering and jammer-nulling processor we present uses relatively simple components; two photorefractive crystals, two single-channel high-speed detectors, and two single channel acousto-optic Bragg cells. The bandwidth capabilities of these components approach a GHz allowing the processing of wide-band signals. The required number of processor components used for implementing the adaptive algorithm is independent of the number of elements in the phased-array in contrast to traditional electronic or acousto-optic approaches[4,5], in which the hardware complexity of the processor scales in proportion to array size. We describe the two main subsystems of the processor, the beam-forming and the jammer-nulling subsystems, and present results demonstrating simultaneous main beam formation and jammer suppression in the combined processor.
Optical diffractometry by rough phase steps
Authors: Moradi Ali-Reza , Siavashani M. Jafari , nasimdoust elyas , Elahi Parviz , Tavassoly Mohammad
Published: February 2023

Optical diffractometry (OD) using a phase step is an elegant alternative for interferometry, further, has least sensitivity to environmental vibrations. Therefore, OD has found numerous interesting metrological and technological applications. OD utilizes a phase step to detect the influence of objects under measurement by the changes in the Fresnel diffraction pattern. Recently, we showed that such measurements do not require infinitively sharp phase steps, although fabrication of such sharp elements is also impossible [1]. Here, we address the issue of smoothness of the phase step surfaces. So far, in all of the OD applications the surfaces of the incorporated phase steps are considered to be optically smooth and flat. However, practically, some amount of roughness and unflatness is unavoidable even in precise and careful fabrication process. We show that preserving the OD-diffraction-pattern characteristics of a phase step depends on the level of roughness in the surfaces of the phase step. We define number of detectable fringes and autocorrelation functions of the diffraction patterns as the measures for evaluating the similarity of the rough phase step diffractions to the ideal case. We derive the theoretical description and confirm the results with simulations and experiments.
Coherent Laser Wind Sensing Review
Authors: Huffaker R. Milton
Published: February 2023

Coherent CO2 lidar systems are proven sensors for the accurate measurement of atmospheric wind velocity. Since 1966, many comparisons have been made between coherent CO2 lidars, cup anemometers, hot wire anemometers, rawinsonde and microwave Doppler radar that demonstrate this accuracy.
NOAA Doppler Lidar Performance Evaluation and Measurement Applications
Authors: Lawrence T. Rhidian
Published: February 2023

Results of investigations undertaken to determine the backscattered power sensitivity and tropospheric wind profiling accuracy of the NOAA pulsed Doppler CO2 lidar will be reported.
Depth-Resolved DIAL Measurements of SO2, NO2, and HCl
Authors: Weitkamp Claus
Published: February 2023

Sulfur dioxide, nitrogen oxides and hydrogen chloride are among the most abundant gaseous air pollutants. They contribute to acid precipitation and, along with ozone and olfactory agents, account almost entirely for the degradation of air quality both near urban centers with intense industrial activity and in more remote areas where vegetation, rather than man, is believed to suffer most from their presence. It is therefore desirable to have a means of detection of these gases that combines sensitivity, space resolution, accuracy, and the capability for both immission and emission type measurements. The present paper describes two differential absorption and scattering lidars (or DIALs), one for SO2 and NO2 and one for HCl, gives a brief account of their performance, and shows examples of practical applications of the systems.
Air Force Program in Visibility Studies
Authors: Fenn Robert W.
Published: February 2023

The Air Force has a continuing program on research into the optical/infrared propagation properties of the atmosphere. The goal of this research is to develop tools that can be used directly in the development and operation of Air Force systems. These tools include data bases, models and computer codes, as well as new measurement techniques.
Separation and analysis of forward scattered power in transmittance measurements of light beams in dense fogs and in laboratory
Authors: Battistelli E. , Bruscaglioni P. , Ismaelli A. , Lo Porto L. , Zaccanti G.
Published: February 2023

The influence of aerosols scattering on the transmittance of light beams through a turbid atmosphere has been the object of many theoretical studies. On the other hand, in comparison with the large variety of the practical conditions, few experimental results are found in the literature.
Infrared Absorption by Water Vapor in the Troposphere
Authors: Thomas Michael E. , Nordstrom Robert J.
Published: February 2023

The most important contributor to infrared absorption in the troposphere is water vapor. This is particularly true for the infrared window regions. Therefore, the understanding and accurate modelling of absorption by this molecule are important to atmospheric remote sensing.
Atmospheric Pressure Profiles Measured Using an Alexandrite Laser Differential Absorption Lidar
Authors: Schwemmer G. K. , Korb C. L. , Dombrowski M. , Kagann R. H.
Published: February 2023

In this paper we describe a high resolution tunable Alexandrite laser system which we have used to make differential absorption lidar measurements of the atmospheric pressure profile. We also report on measurements of the spectral purity and line shape of the laser emission.
The Use of Lidar in Japan for Studies of Atmospheric Environment
Authors: Takeuchi Nobuo
Published: February 2023

The data size of lidar measurement is huge just like radar. Before the introduction of computer with analog-to-digital conversion technique, the lidar data processing was an enormous task and a high accuracy data could not be expected. The recent development of computer technology has made lidar technique matured and the lidar has become a practical instrument for atmospheric research and monitoring. In Japan this occasion coincided with the time of change of air pollution aspects. After the tight regulation against the severe air pollution brought by the rapid economic growth, air pollution was reduced to the lower level. With this change, the role of lidar in Japan shifted from the high-level air pollution monitoring to the measurement of phenomena relating to air pollution, such as features of atmospheric boundary layer and dispersion of plumes in various scales. For that purpose, a large number of groups over Japan are engaging in developping the lidar technique. The groups and their locations are shown in Fig. 1, including other fields such as geodesy and millitary.
Validation measurements of the inherent calibration of differential absorption lidar
Authors: Lahmann W. , Staehr W. , Baumgart R. , Breinig A. , Weitkamp C. , Michaelis W.
Published: February 2023

Differential absorption and scattering lidar measurements exhibit inherent calibration. This is due to the structure of the lidar equation and to the fact that its inversion results in an expression for the concentration n(x) of the absorbing gas that is independent of lidar system parameters such as receiver area, optical system transmittance and detector quantum efficiency: Apart from laboratory measurements of the absorption cross sections σ at the on-resonance wavelength λ1 and the off-resonance wavelength λ0 only the power p(x,λ0) and P(x,λ1) of the backscattered radiation must be measured.
The Sensitivity of the SAGE II .94 μm Band Water Vapor Retrievals to Uncertainties in Absorption Line Parameters
Authors: Larsen Jack C. , Chu William P.
Published: February 2023

The Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument is a multi-channel sun photometer designed to measure aerosol and molecular scattering, and absorption due to ozone, nitrogen dioxide and water vapor from space. SAGE II is mounted on the Earth Radiation Budget Satellite (ERBS) which is scheduled to be deployed by the space shuttle in the early part of October, 1984. Ozone and nitrogen dioxide have been measured previously with the SAGE1 satellite system. The radiative transfer calculations for these two gases are relatively simple because of the lack of line structure in these bands and the insensitivity of the absorption cross sections to pressure and temperature. The .94 μm water vapor band covered by SAGE II, however, requires time consuming line-by-line radiative transfer calculations to model. Line by line calculations are impractical for the reduction of large amounts of limb occultation satellite data and tradeoffs between accuracy and speed must be considered2. This paper discusses the radiative transfer code selected for use in the water vapor retrieval algorithm and presents several sensitivity studies conducted with this code.
Compact Shuttle Lidar for Global Observations of Atmospheric Waves in the Mesospheric Sodium Layer
Authors: Gardner Chester S. , Bufton Jack L. , Philbrick C. Russel
Published: February 2023

A compact lidar system is being developed to measure the mesospheric sodium layer from the space shuttle. The lasers, telescope, batteries and data acquisition system are mounted in three Get-a-Way Special (GAS) canisters. By mixing the 1064 nm and 1319 nm outputs from two YAG lasers in a LiIO3 crystal, the sum frequency is generated at the sodium D2 resonance wavelength (589 nm).
The Earth Observing System: Atmospheric Science in the 1990s and Beyond
Authors: Wilson Stanley , Eckman Richard
Published: February 2023

An overview of the Earth Observing System, a long-term mission to measure and interpret global change, is presented. Its configuration and instrument complement for atmospheric observations are examined.
Improvements in Remote Sensing of Volcanic Sulfur Dioxide
Authors: Krueger Arlin J. , Morin Luce
Published: February 2023

Sulfur dioxide in volcanic eruption clouds was detected from space using data from the Total Ozone Mapping Spectrometer (TOMS) instrument on the Nimbus 7 satellite (Krueger, 1983) and confirmed in data from the SBUV instrument on the same satellite (McPeters and Heath, 1984). The detection was possible because sulfur dioxide has strong absorption bands in the same wavelength region of the near ultraviolet that was selected for measuring total ozone with these satellite instruments. The background levels of sulfur dioxide are so low that the measurement of ozone can normally be made without accounting for any interference from this gas. However, volcanic eruptions can produce millions of tons of sulfur dioxide in compact clouds which locally dwarf the absorption by ozone. Even as the eruption cloud is dispersing the absorption by sulfur dioxide can be comparable to that of ozone.
"Heterodyne Mixing Efficiency Modeling: Applications to LAWS Type Instruments"
Authors: Kenyon D. , Prutzer S. , Shanley J.
Published: February 2023

A numerical model for calculating the receiver mixing efficiency for heterodyne Lidar systems which includes the effects of optical aberrations is presented.
Limb Emission Measurements with the Balloon Version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)
Authors: Fischer H. , Oelhaf H. , Fergg F. , Fritzsche Chr. , Piesch Chr. , Rabus D. , Seefeldner M. , Friedl-Vallon F. , Völker W.
Published: February 2023

Spatial distributions of simultaneously measured concentrations of atmospheric trace constituents are needed in order to improve our knowledge of middle atmospheric chemistry, dynamics and energy budget. Fourier Transform Spectrometers are especially appropriate for providing such a data base. For studying nighttime and polar winter conditions it is necessary to perform emission measurements. A high spectral resolution, rapid scanning FTS with a novel optical design has been developed for the mid IR region. An uncooled laboratory model (MIPAS-LM) providing an apodized spectral resolution of 0.03 cm-1 has been completed in 1987. This instrument version is being used for operation as a ground based device for measuring column amounts of trace gases at midlatitude mountain and polar stations. A cooled version of MIPAS has been designed in order to serve the great need for data on diurnal variations of trace constituents and on the compositon and structure of the polar stratosphere. This instrument version is capable for observing the thermal emission of the atmosphere from platforms operating within the stratosphere and outside of the atmosphere.
Spectral Calibration of the Cryogenic Limb Array Etalon Spectromerer (CLAES)
Authors: James T.C. , Roche A. E. , Steakley B.C. , Thatcher J. B. , Kumer J. B. , Steritt L.W. , Potter J.F. , Dawson J. C.
Published: February 2023

The Cryogenic Limb Array Etalon Spectrmeter (CLAES) will derive Stratospheric temperatures and constituent number densities from the measurement of infrared spectral emissions during its 18 month mission on board the NASA Upper Atmosphere Research Satellite (UARS). Overviews of the CLAES experiment and hardware are given by Roche et. al. (Ref 1) and Burriesci et. al. (Ref 2).
Compensation for Tangent Altitude Smear in CLAES Spectral Measurements
Authors: Uplinger W. G. , Kumer J. B. , Ely G. A. , Mergenthaler J. L.
Published: February 2023

The Cryogenic Limb Array Etalon Spectrometer (CLAES) will derive Stratospheric temperatures and constituent number densities from the measurement of infrared spectral emissions, during its 18 month mission on board the NASA Upper Atmosphere Research Satellite (UARS). Overviews of the CLAES experiment and hardware are given by Roche et al (Ref 1) and Burriesci et al. (Ref 2). CLAES earthlimb spectral measurements consist of discrete narrow band spectral measurements within a spectral micro-window defined by a some what broader band blocker filter. The narrow spectral channels are of the order 0.2 to 0.6 cm-1, depending on spectral region. The blocker filter bands are of the order 3 to 12 cm-1. There are 9 blocker regions spaced across the range 3.5 to 12 micrometers wavelength. The blocker regions are selected for retrieval of HCI (~ 2843 cm-1), NO (~ 1897 cm-1), H2O and NO2 (~ 1605 cm-1), CH4, N2O, and N2O5 (~ 1257 cm-1), F12 (~925 cm-1), HNO3 (879 cm-1), F11 (843 cm-1), temperature (CO2) and 03 (~792 cm-1) and ClONO2 (780 cm-1).
Photoacoustic Correlation Spectroscopy
Authors: Shakkottai P. , Margolis J. S.
Published: February 2023

Photoacoustic (PA) correlation spectroscopy offers some advantages over conventional correlation spectroscopy in that the PA detector requires no cooling. The method has been proposed earlier (Perlmutter, *et al) , but was not considered sensitive enough to warrant further work. In this study we consider Perlmutter's formulation and show how the sensitivity may be improved by including an electro optic phase modulator (EOPM) for modulation of the radiation.
A Far Infrared Fabry-Perot Spectrometer
Authors: Pickett H. M. , Peterson D. B.
Published: February 2023

A balloon-borne Far Infrared Limb Observing Spectrometer (FILOS) has been developed for remote sensing of the stratosphere. Measurements of OH, H2O, O3, and HDO have been made near 101 cm−1 (99 µm). The instrument uses a triple Fabry-Perot design with a resolution of 0.002 cm−1, and is small and light-weight. A schematic diagram of the instrument is shown below. The instrument package is 24” × 48” × 19” and weighs 63 kg. The data rate is 110 bits/sec and the power consumption is 30 W. These specifications allow the instrument to be installed on the service floor of the JPL gondola, where it can participate in joint balloon flights with larger payloads.
Intercomparison of Lidar and In-Situ Tropospheric Measurements
Authors: Cunningham A.G. , Carswell A.I. , Pal S.R. , Leaitch W.R.
Published: February 2023

Lidar as a technique for stand-alone optical remote sensing of atmospheric extinction seems ideally suited. Its ability to provide highly range-resolved data with excellent temporal resolution on small atmospheric volumes from a single source point suggests that it may be useful for three-dimensional investigation of atmospheric properties.
Noise Reduction in a Sequence of Limb Emission Spectra by Fourier Filtering of Spectral Radiance Profiles
Authors: Clarmann Thomas V. , Oelhaf Hermann , Fischer Herbert
Published: February 2023

A sequence of atmospheric spectra measured in limb sounding mode is often evaluated by using the onion peeling method. A major disadvantage of onion peeling is that instabilities are caused by error propagation. Resulting profiles of minor constituents of the atmosphere show typical zigzag features. By appropriate preprocessing of measured noisy data, the applicability of the onion-peeling-method can be improved.
Wideband Filter Spectrophotometer for Mesospheric and Thermospheric Studies
Authors: Skinner Wilbert R. , Yee Jeng-Hwa
Published: February 2023

The effect of small scale features, such as gravity waves, on the mesosphere and lower thermosphere is a subject of much current interest. One way to study these phenomenon is to monitor their effects on the airglow emissions originating in the region. Band emissions, such as the OH Meinel and O2 Atmospheric bands are particularly useful. Instrumentally these are difficult to study because of their wide spectral nature and low intensity. Often, it is necessary to infer the properties of an entire band from the observations of a few lines with either a filter photometer or a Fabry-Perot interferometer (Meriwether, 1975). Another approach has been to scan a band with a grating spectrometer, a process that is often slow compared to many of the temporal features of interest (Myrabo and Deehr, 1984).
Comparison of Sage II and Umkehr Ozone Profiles as Functions of Stratospheric Optical Depth, Total Ozone, Season, and Tropopause Height
Authors: Newchurch M.J. , Cunnold D.M.
Published: February 2023

Comparison of SAGE II and Umkehr ozone at 9 northern stations indicates significant differences in various layers as functions of station, stratospheric aerosol optical depth, total ozone, season, and tropopause height.
Lidar Measurements of Ozone, Water Vapor, and Aerosols
Authors: Browell Edward V.
Published: February 2023

During the last 2 years, major advances have taken place in the development and application of airborne lidar systems in the study of large-scale atmospheric processes. The first simultaneous measurements of ozone (O3) and aerosol distributions above and below an aircraft were made in tropospheric investigations in the Arctic during the summer of 1988 as part of the NASA Global Tropospheric Experiment. During the 1989 Airborne Arctic Stratospheric Experiment, the first large-scale distributions of O3 and polar stratospheric clouds (at multiple laser wavelengths) were obtained with an airborne lidar system on long-range flights into the wintertime polar vortex. In addition, the first water vapor (H2O) profile measurements were obtained using an Alexandrite laser in an airborne differential absorption lidar (DIAL) system over the Atlantic during the summer of 1989.
Balloon-borne Laser In-situ Measurements of NO, NO2, HNO3, HCl, O3, N2O, and the Nighttime Decay of NO2; a Comparison with Remote Sensing Measurements.
Authors: Webster C. R. , May R. D. , Toumi R. , Pyle J. A.
Published: February 2023

This paper describes the results of two recent stratospheric balloon flights of the Balloon-borne Laser In-Situ Sensor (BLISS) instrument1,2,3, and compares them with measurements made using remote sensing techniques, and with photochemical model predictions. This comparison is used to illustrate the complementarity of in-situ and remote sensing methods, and to further define the role of in-situ measurements for satellite ground-truth and correlative measurements.
Non-LTE Considerations for Remote Sensing of the Atmosphere
Authors: Taylor FW
Published: February 2023

The interpretation of infrared observations of the upper atmosphere is often complicated by the effects of non-LTE (where LTE stands for local thermodynamic equilibrium). This arises whenever collisions between molecules are infrequent enough that the radiative lifetimes of the important vibrational energy states of a molecule become comparable to the mean time between collisions. Although it depends on the state being considered, NLTE typically becomes important at pressures of the order of one mb, or heights above the surface of around 50 km. Then the populations of the internal energy states are no longer related to the kinetic temperature of the gas by simple Boltzmann statistics, but rather by a more complex dependence on radiative exchange of quanta as well as collisional reactions. Under non-LTE conditions, the latter can involve both vibrational - thermal and vibrational-vibrational exchanges, often with a multiplicity of levels and of exchange partners. As a result it becomes quite difficult to perform reliable calculations of the source function, as required to interpret radiance measurements in terms of upper atmospheric temperature structure, or to incorporate the non-LTE energy exchange into dynamical models of the region.
The Effect of Non-LTE Emission by CO2 on the Total Limb Radiance in the 9 μm - 11 μm Spectral Interval
Authors: Mlynczak Martin G. , Drayson S. Roland , Lee Kwang-Mog
Published: February 2023

Passive remote sensing experiments that monitor the spectrally integrated limb infrared emission from various constituents in the middle atmosphere are successful only if it is possible to accurately characterize the emission from both the target species and from all other species that emit within the bandwidth of each particular radiometric channel. Accurate characterization of the measured radiances is necessary if the equation of transfer is to be inverted to yield profiles of kinetic temperature and minor constituent concentration as a function of altitude. It is, therefore, essential to have an excellent understanding of the processes that give rise to the radiative emission from each species.
CO2 Non-LTE Effects in a Line-by-Line Radiative Excitation Model
Authors: Wintersteiner P.P. , Picard R.H. , Sharma R.D. , Nebel H. , Paboojian A.J. , Winick J.R. , Joseph R.A.
Published: February 2023

We have developed a radiative-transfer algorithm for infrared bands in the terrestrial atmosphere and used it to calculate non-LTE vibrational populations of CO2 (described here) and CO (described in a companion paper1). A unique feature of our model is that it incorporates a complete line-by-line transport algorithm. All the effects of the variations in the emission and absorption lineshapes with altitude (for example, due to temperature and pressure dependence) are accounted for. The absorption is calculated on a monochromatic basis for points within each line and then integrated, and this is done for all lines in all ro-vibrational bands in which radiative transport is significant.
Stratospheric Monitoring Stations in Europe
Authors: Simon P.C. , de Maziere M. , Delbouille L. , Roland G. , GODIN S. , Kunzi K. , de La Noe J. , Woods P.T.
Published: February 2023

Measurements of the trends in ozone and other stratospheric trace species require a coordinated scientific effort in establishing ground based observations coupled with satellite measurements in order to quantitatively detect early changes in stratospheric composition and structure and to improve the understanding of short term processes needed to validate either long term observations or model simulations.
New Lidar Atmospheric Observatory
Authors: Carswell A.I. , Kitaura E. , Pal S.R. , Steinbrecht W. , Ulitsky A. , Whiteway J.A. , Zhao X.
Published: February 2023

A new atmospheric lidar observatory has been established during the last year as part of the research program of the Institute for Space and Terrestrial Science. The observatory is located on the campus of York University in the northwestern part of Toronto. (43.8 N, 79.5 W) and is intended to provide a comprehensive capability for lidar measurements of the atmosphere.
Remote Sensing Using Solid-State Lasers, Progress and Projections
Authors: Barnes Norman P.
Published: February 2023

Performance of two tunable lidar transmitters, one in the near-infrared and one in the mid-infrared, being developed by NASA Langley are reviewed. Current status and projections for performance parameters such as wavelength tuning range, energy per pulse, and efficiency will be given.
First operation of the ENEA CO2 LIDAR/DIAL station
Authors: Barbini R. , Colao F. , Palucci A. , Ribezzo S. , Orlando S.
Published: February 2023

The ENEA ground-based LIDAR/DIAL apparatus has been designed for remote measurements of pollutant and minor atmospheric gaseous species and more generally to investigate the physical parameters of the atmosphere.
Remote Sensing of Airborne Hydrocarbons and Toxic Pollutants - Present Status And Future Projections
Authors: Hall Freeman F.
Published: February 2023

Remote sensing technology is now ready and able to play a significant role in monitoring Clean Air Act compliance.
Development of a 1.54 μm Eyesafe Raman-Shifted Lidar
Authors: Patterson Edward M. , Roberts David W. , Gimmestad Gary G.
Published: February 2023

Eyesafe operation is desirable when lidar systems are used in programs in which personnel can be in the path of the laser beam. This is of particular importance in scanning systems, or in systems that are designed for automated, unattended operation. In practice, in order to be eyesafe at short ranges from the transmitter and still maintain a reasonable pulse energy output, the source wavelength must be shorter than 400 nm or longer than 1.4 μm [1]. With the exception of long wavelength CO2 systems, commonly used lidar systems are not eyesafe and require stringent precautions for safe operation. Since these CO2 systems have several disadvantages, including reduced detector/preamp performance at 10 μm and the need for cryogenically cooled detectors, there is a need for a short wavelength lidar that is capable of eyesafe operation. Interest in the properties of the atmosphere at near infrared wavelengths and recent developments in detectors have made the concept of an eyesafe system in the range of 1.4 to 1.8 μm an attractive option.
Frequency Stabilization of an Alexandrite Laser for Pressure - Temperature Lidar Measurements
Authors: Prasad C. R. , Korb C. L. , Schwemmer G. K.
Published: February 2023

The pressure - temperature differential absorption lidar1-3 utilizes two narrow band tunable pulsed alexandrite lasers. For tuning and narrow band operation, the on-line high resolution laser has three intracavity elements which are a birefringent filter, a tilt tuned thin etalon and a piezoelectrically tuned etalon. To obtain accurate temperature measurements, a line center frequency stability and accuracy of ±0.002 cm-1 is required over an extended period of time, typically ~ 30 min, which corresponds to a set of measurements and in addition the spectral bandwidth of the on-line laser should be less than 0.02 cm-1. A wavemeter consisting of a 5 cm coated Fizeau wedge and a Reticon detector array (with 1024 detector elements spaced at 25 μm) has been developed4 to measure the frequency and spectral line shape of the laser. Typically the output spectrum of the on-line alexandrite laser consists of three longitudinal modes which are spaced about 0.007 cm-1 apart.
Ground Based Dial Ozone Measurements at Mcmurdo Station, Antarctica During The 1987 Austral Spring
Authors: Burris J. , Heaps W. , Cavanaugh J.
Published: February 2023

Ozone profiles were measured above McMurdo Station, Antarctica, using a ground-based differential absorption lidar (DIAL) instrument during the 1987 austral spring. The instrument generated radiation at 292 and 297 nm using the frequency doubled output of a dye laser dumped by 532 nm light. Profiles were obtained on nine days from 21 Sept, through 07 Oct. 87. Profiles displayed typical tropospheric ozone values between altitudes of five and ten kilometers. Between ten and fifteen kilometers structure was observed on several nights with peaks in ozone concentration near 11-13 km and minimums at 15-16 km. PSCs were observed on several nights at altitudes ranging from 12 to 15 km. Unusual extinction in the laser signal returns was noted on several nights at altitudes from 12-16 kilometers and was usually correlated with PSC activity. Signal cutoff generally occurred within a range cell of 300 meters and when seen always appeared on the 292 nm channel although it was sometimes also observed at the 297 nm wavelength. Its duration was from minutes to many hours. No evidence for enhanced backscattering near the extinction region was observed.
Lidar and radiometry (LIRAD) Sensing of Cloud Properties
Authors: Platt C.M.R.
Published: February 2023

Clouds are now recognized as one of the major stumbling blocks to the proper understanding of predicted global wanning resulting from the increase of anthropogenic gases in the atmosphere.
Optimal Heterodyne Detector Array Size for 1μm Coherent LIDAR
Authors: Sugimoto Nobuo , Chan Kinpui , Killinger Dennis K.
Published: February 2023

We have investigated the optimal detector size for a coherent Dopplar LIDAR which takes into account the telescope/receiver geometry, heterodyne detector array, and atmospheric turbulence. Our analysis (computer simulation) indicates that atmospheric turbulence severely limits the optimal size of a heterodyne detector and that significant improvements in the overall detection efficiency can be obtained by the use of a detector array. These numerical studies are important because they help to explain our recent experimental results using a 1.06μm Nd:YAG coherent Doppler LIDAR
Remote Sensing Measurements of Fluorescence Lifetimes
Authors: Yee Young P. , Gonzalez Raul , Loveland Radon B.
Published: February 2023

The Army has a continuing need for remote sensing methods in the area of target identification. One promising lidar technique for this purpose is use of ultraviolet - induced fluorescence (Measures, 1984). To enhance the identification capability of an ultraviolet lidar fluorescence system, we conducted measurements to demonstrate the feasibility of using fluorescence lifetimes to discriminate reference substances.
Polar Ozone Research with an Airborne Fourier Transform Spectrometer
Authors: Mankin William G. , Coffey M. T.
Published: February 2023

The discovery by Farman et al. (1985) of a large springtime depletion of ozone over Halley Bay, Antarctica and its subsequent confirmation by satellite observations as a large scale progressive phenomenon led to intensive theoretical and experimental investigation to determine the cause of this potentially dangerous effect. Many of the theoretical approaches centered on modifications of stratospheric chemistry by polar stratospheric clouds. Several experimental expeditions were mounted to Antarctica to make observations to verify or disprove the theories.
Comparison of Aerosol and Ozone Climatologies from SAGE II and Groundbased Measurements
Authors: DeLuisi J. , DeFoor T. , Komhyr W. , Longenecker D. , McNice T. , Chu W.
Published: February 2023

Ozonesonde, Umkehr, and lidar aerosol data obtained at Mauna Loa and Boulder from 1984-1988 are compared with SAGE II data and the results are discussed.
Operational Processing of Infrared Limb Radiance Using Line-by-Line Calculations
Authors: Gordley Larry L. , Marshall Benjamin T. , Mlynczak Pamela E.
Published: February 2023

The retrieval of information from measured limb radiance is usually done by iteration of the unknown independent parameters in a forward model until measurement matches calculation. The extremely non-linear nature of the atmospheric infrared radiative transfer equation requires a very accurate model, particularly for emission. Ideally, a rigorous line-by-line calculation should be done for each atmospheric state addressed. Past limitations in algorithms, hardware, and dollars (or a combination of the same) confined such calculations to small data sets or research simulations. However, improvements in algorithms and computer hardware have made the ideal possible, for many applications, on relatively inexpensive systems. This paper will give an overview of algorithms, methodology, and hardware now being prepared for use in the reduction of future data sets from HALOE (The Halogen Occultation Experiment) to fly on UARS and SAFIRE (Spectroscopy of the Atmosphere using Far Infra-Red Emission) scheduled to fly on the second EOS polar platform. Several high resolution multipath examples with timing benchmarks on different machines are presented.
Measurements of Infrared Line Parameters of Atmospheric Trace Gases at Relevant Temperatures using a Tunable Diode Laser†
Authors: Varanasi P.
Published: February 2023

It has long been recognized that atmospheric transmittance through columns of trace gases cannot be determined based upon laboratory measurements at room temperature alone. For example, through an inhomogeneously and non-isothermally distributed column of chlorofluorocarbons (CFCs) in the real atmosphere the spectral transmittance would show a shifting of the spectral peaks from their positions observed at room temperature in the laboratory. The extent to which the transmittance profiles would be different from the room temperature observations can only be determined by laboratory measurements of absorption coefficients at lower temperatures. Examples of such measurements, which are currently in progress in our laboratory, are illustrated in Figs. 1 and 2. At lower temperatures, the contributions from the “hot bands”, which represent absorption of photons that results in transitions from an excited state with nearly the same energy as involved in the ground state bands, are smaller. If hot bands were not present, the band strength per atmosphere of the absorbing gas would be inversely proportional to the temperature making S
V
T a constant. Such is not the case with the CFC bands as can be seen clearly in Table 1.
Polarization and Possible Differences in Backscatter Measurements
Authors: Anderson Richard
Published: February 2023

In the fall of 1989 a series of flights were made to compare backscatter measurements performed by different lidars and a second flight may be made in the spring of 1990. The lidars to be compared may be monostatic and bistatic systems and will transmit light of one state of polarization and analyze received light in a different state of polarization. In this paper the nature of the signals will be analyzed by a vector-matrix theory where the light is represented by (4x1) Stokes vectors and the interaction with the atmosphere is represented by a (4x4) Mueller matrix. In each apparatus a value for β, the volume backscatter coefficient, is measured and it will be sums of differences of certain components of the
β^ matrix which will depend upon the polarization properties of the laser. Pritchard and Elliott1 have performed a similar analysis for an atmospheric polarimeter but they studied a fixed target of magnesium oxide. This discussion will assume a pulsed lidar (rectangular pulse of width τ) so a thin slab of the atmosphere of thickness cτ/2 centered about Rs=c(t/2−τ/2) is examined.
Retrieval of Tropospheric Ozone from Simulations of Spectral Radiances as Observed from Space
Authors: Clough Shepard A. , Rinsland Curtis P. , Rodgers Clive D. , Goldman Aaron
Published: February 2023

A critical measurement to be performed by future high resolution spectral radiometers such as the Tropospheric Emission Sounder (TES; Beer and Glavitch, 1989), is the global profiling of ozone. In order to assess the capability of retrieving tropospheric ozone profiles using a space based Fourier Transform Spectrometer (FTS) observing in the nadir, retrieval studies have been performed using simulated spectral radiances. The approach we have used in studying tropospheric ozone profile retrievals is the maximum likelihood method (Rodgers, 1987). This method is attractive for two principal reasons: (1) null space is systematically treated and (2) a consistent error analysis of the retrieved parameters is provided. The effect on the retrievals of supplementing the spectral thermal emission radiances in the 10 micron ozone band with scattered solar spectral radiances from the three micron ozone region has been studied. These studies have been performed with an unapodized resolution of 0.071 cm-1 and with measurement noise consistent with the specifications for TES. The entire spectral ozone region at 10 microns has been utilized in these studies taking advantage of the TES capability to provide a simultaneous measurement over a broad spectral range.