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NASA NTRS1992

Satellite aerosols retrieval over land surfaces using the structure functions

Remote sensing of aerosol optical thickness from space is difficult over continental surfaces. There are two retrieval algorithms, one based on the use of dark targets and a second based on contrast reduction between selected pixels. Improvements in the contrast reduction method are reported. A procedure is developed for using the satellite image to evaluate whether conditions for applying the structure method are met. The theoretical background is discussed, and the usefulness of the structure functions is demonstrated. The method is applied to NOAA Advanced Very High Resolution Radiometer (AVHRR) imagery where simultaneous ground measurements are used for validation.

Tanre, D.↗
NASA NTRS1993

EUVE telemetry storage and retrieval

A system for archiving and retrieval of EUVE telemetry is described. The goals of the system design include archiving with no loss of information and providing flexibility of access that is based on criteria meaningful to the user and that is also independent of storage implementation. User access to the archival telemetry is provided in a stream-oriented fashion based on time. The mapping of time intervals to file locations on storage media is implemented with a relational database.

Girouard, Forrest R.↗
NASA NTRS1993

Third LDEF Post-Retrieval Symposium Abstracts

This volume is a compilation of abstracts submitted to the Third Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The abstracts represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science.

Levine, Arlene S.↗
NASA NTRS1992

A linear spectral matching technique for retrieving equivalent water thickness and biochemical constituents of green vegetation

Over the last decade, technological advances in airborne imaging spectrometers, having spectral resolution comparable with laboratory spectrometers, have made it possible to estimate biochemical constituents of vegetation canopies. Wessman estimated lignin concentration from data acquired with NASA's Airborne Imaging Spectrometer (AIS) over Blackhawk Island in Wisconsin. A stepwise linear regression technique was used to determine the single spectral channel or channels in the AIS data that best correlated with measured lignin contents using chemical methods. The regression technique does not take advantage of the spectral shape of the lignin reflectance feature as a diagnostic tool nor the increased discrimination among other leaf components with overlapping spectral features. A nonlinear least squares spectral matching technique was recently reported for deriving both the equivalent water thicknesses of surface vegetation and the amounts of water vapor in the atmosphere from contiguous spectra measured with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). The same technique was applied to a laboratory reflectance spectrum of fresh, green leaves. The result demonstrates that the fresh leaf spectrum in the 1.0-2.5 microns region consists of spectral components of dry leaves and the spectral component of liquid water. A linear least squares spectral matching technique for retrieving equivalent water thickness and biochemical components of green vegetation is described.

Gao, Bo-Cai↗
NASA NTRS1992

Retrieval of biophysical parameters with AVIRIS and ISM: The Landes Forest, south west France

The first steps of an experiment for investigating the capability of airborne spectrometer data for retrieval of biophysical parameters of vegetation, especially water conditions are presented. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and ISM data were acquired in the frame of the 1991 NASA/JPL and CNES campaigns on the Landes, South west France, a large and flat forest area with mainly maritime pines. In-situ measurements were completed at that time; i.e. reflectance spectra, atmospheric profiles, sampling for further laboratory analyses of elements concentrations (lignin, water, cellulose, nitrogen,...). All information was integrated in an already existing data base (age, LAI, DBH, understory cover,...). A methodology was designed for (1) obtaining geometrically and atmospherically corrected reflectance data, (2) registering all available information, and (3) analyzing these multi-source informations. Our objective is to conduct comparative studies with simulation reflectance models, and to improve these models, especially in the MIR.

Zagolski, F.↗
NASA NTRS1992

A snow wetness retrieval algorithm for SAR

The objectives of this study are: (1) to evaluate the backscattering signals response to snow wetness; and (2) to develop an algorithm for snow wetness measurement using C-band polarimetric synthetic aperture radar (SAR). In hydrological investigations, modeling and forecasting of snowmelt runoff requires information about snowpack properties and their spatial variability. In particular, timely measurement of snow parameters is needed for operational hydrology. The liquid water content of snowpack is one of the important parameters. Active microwave sensors are highly sensitive to liquid water in the snowpack because of the large dielectric contrast between ice and water in the microwave spectrum. They are not affected by weather and have a spatial resolution compatible with the topographic variation in alpine regions. However, a quantitative algorithm for retrieval snow wetness has not yet been developed.

Shi, Jian-Cheng↗
NASA NTRS1993

The Test Analysis Retrieval System (TARS): Meeting the challenges of the network's test processes

The Networks Systems Test Section (GSFC 531.4) is responsible for managing a variety of engineering and operational tests used to assess the status of the Network elements relative to readiness certification for new and ongoing mission support and for performance trending. To conduct analysis of data collected during these tests, to disseminate and share the information, and to catalog and create reports based on the analysis is currently a cumbersome and inefficient task due primarily to the manual handling of paper products and the inability to easily exchange information between the various Networks elements. The Test Analysis and Retrieval System (TARS) is being implemented to promote concise data analysis, intelligible reporting of test results, to minimize test duplication by fostering a broad sharing of test data, and perhaps most importantly, to provide significantly improved response to the Network's internal and external customers. This paper outlines the intended application, architecture, and benefits of the TARS.

Stelmaszek, Robert L.↗
NASA NTRS1993

Measured space environmental effects to LDEF during retrieval

Data gathered by the Interim Operational Contamination Monitor (IOCM) with regard to the effect of the space environment on the STS-32 Shuttle mission and on the Long Duration Exposure Facility (LDEF) are reported. IOCM measures the deposition of molecular and particulate contamination during all flight phases. It also measures the thermophysical properties of thermal control surfaces by calorimetry, the flux of the ambient atomic oxygen environment, the incident solar flux, and the absolute ambient pressure in the payload bay. The IOCM also provides a structure and sample holders for the exposure of passive material samples to the space environment. One of the more salient results from the STS-32 flight suggests that the LDEF emitted a large number of particulates after berthing into the Shuttle. The mission atomic oxygen fluence was also calculated. Although the fluence was low by normal standards, the Kapton (trademark) passive samples exhibited the onset of erosion. Orbital debris and micrometeoroid impacts also occurred during the retrieval mission. The average perforation diameter was approximately 1.25 micrometers. The largest perforation diameter was measured at 65 micrometers.

Maag, Carl R.↗
NASA NTRS1993

Microphysical properties of the November 26 cirrus cloud retrieved by Doppler radar/IR radiometer technique

Gaining information about cirrus cloud microphysics requires development of remote sensing techniques. In an earlier paper. Matrosov et al. (1992) proposed a method to estimate ice water path (IWP) (i.e., vertically integrated ice mass content IMC) and characteristic particle size averaged through the cloud from combined groundbased measurements of radar reflectivities and IR brightness temperatures of the downwelling thermal radiation in the transparency region of 10-12 mu m. For some applications, the vertically averaged characteristic particle sizes and IWP could be the appropriate information to use. However, vertical profiles of cloud microphysical parameters can provide a better understanding of cloud structure and development. Here we describe a further development of the previous method by Matrosov et al. (1992) for retrieving vertical profiles of cirrus particle sizes and IMC rather than their vertically averaged values. In addition to measurements of radar reflectivities, the measurements of Doppler velocities are used in the new method. This provides us with two vertical profiles of measurements to infer two vertical profiles of unknowns, i.e., particle characteristic sizes and IMC. Simultaneous measurements of the IR brightness temperatures are still needed to resolve an ambiguity in particle size-fall velocity relationships.

Matrosov, Sergey Y.↗
NASA NTRS1993

Studies in remotely sensed geophysical parameter retrieval and analysis

This report describes Universities Space Research Association (USRA) activities in support of the Geophysical Parameter Retrieval and Analysis studies. Specifically it addresses personnel assigned to the effort, travel, consultant participants, technical progress, and contract spending.

Perkey, Donald J.↗
NASA NTRS1992

Intelligent text retrieval in the NASA astrophysics data system

In collaboration with the NASA Scientific and Technical Information System, the NASA Astrophysics Data System (ADS) is establishing a service to provide access to the literature abstracts relevant to astronomy in the NASA Scientific and Technical Aerospace Reports and the International Aerospace Abstracts (together also known as NASA RECON). The service will include several sophisticated retrieval methods, which may be combined. Included will be methods to perform relevancy ranking from natural language queries, synonym and misspelling recognition, author name translation (e.g. for multiple transliteration possibilities), and other features. The capabilities of the current release will be shown, and the plans for the near future will be discussed.

Kurtz, M. J.↗
NASA NTRS1993

Spacehab debut: Eureca retrieval - STS-57 launch

A review is presented of the STS-57 mission. The events leading up to launch are reviewed in some detail, with emphasis on the handling of the payload. A day-by-day recounting of the mission is given, including the activities in the Spacehab module and the retrieval of the Eureca satellite.

Schuiling, Roelof L.↗
NASA NTRS1994

Profile shape dependence in backscattered ultraviolet satellite retrievals of total ozone

Total ozone operational algorithms use climatological mean ozone profiles. When the actual ozone profiles have significantly different shapes versus the climatology and the solar zenith angles are large, retrieved total ozone will have an error. Recalibrated SBUV profiles are used to estimate this error. Preliminary results suggest that, on the average, the change and variation in significant profiles shapes can to a large degree be estimated by the SBUV derived profiles. Preliminary results suggest the average error in the report algorithm ozone trend (trend in reported ozone) from profile shape is relatively small during the north hemisphere winter (less than 2 percent) for solar zenith angles less than 82 degrees (for 60 degrees North Latitude).

Taylor, S. L.↗
NASA NTRS1993

Retrieval of cirrus cloud parameters from satellite observations: Evaluation from field experiments

Knowledge on cirrus clouds gained from experiments involving in situ observations in close coordination with ground and aircraft based remote sensing, as well as satellite observations and other conventional observations such as rawinsondes, is presented. The methodologies used to retrieve cirrus cloud parameters from satellite observations are reviewed, results from field campaigns are discussed in terms of these methods, and prospects for satellite remote sensing of cirrus are discussed.

Starr, David OC.↗
NASA NTRS1994

Post-flight investigation programmes of recently retrieved solar generators

In 1993 two ESA solar power generators were successfully retrieved from space: EURECA with its 10 panel rigid array in August, after 11 months in a 500 km orbit, and one of the two flexible Hubble Space Telescope (HST) arrays in December, after almost 4 years in a 600 km orbit. Both solar generators are undergoing separate post-flight investigation programs (PFIP). These programs cover investigations of all solar array (SA) components and mechanisms. Since both programs have much in common, most of the component and material investigations are the same. Extremely valuable information on numerous essential subjects, such as atomic oxygen, radiation, meteoroid and space debris environment resulting damage, low cycle fatigue, material degradation, etc. are expected to be obtained for both types of arrays. We will also be able to explain and understand the anomalies experienced on both solar arrays in orbit. The paper will outline both post-flight investigation programs and will concentrate on reporting the first results and findings.

Grelach, Lothar↗
NASA NTRS1995

LDEF: 69 Months in Space. Third Post-Retrieval Symposium, part 1

This volume (Part 1 of 3) is a compilation of papers presented at the Third Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science. In addition, papers on preliminary data analysis of EURECA, EOIM-3, and other spacecraft are included.

Levine, Arlene S.↗
NASA NTRS1995

LDEF: 69 Months in Space. Third Post-Retrieval Symposium, part 2

This volume is a compilation of papers presented at the Third Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science. In addition, papers on preliminary data analysis of EURECA, EOIM-3, and other spacecraft are included. This second of three parts covers spacecraft construction materials.

Levine, Arlene S.↗