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Results for “ATMOSPHERIC ATTENUATION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Correcting infrared satellite estimates of sea surface temperature for atmospheric water vapor attenuation

A new satellite sea surface temperature (SST) algorithm is developed that uses nearly coincident measurements from the microwave special sensor microwave imager (SSM/I) to correct for atmospheric moisture attenuation of the infrared signal from the advanced very high resolution radiometer (AVHRR). This new SST algorithm is applied to AVHRR imagery from the South Pacific and Norwegian seas, which are then compared with simultaneous in situ (ship based) measurements of both skin and bulk SST. In addition, an SST algorithm using a quadratic product of the difference between the two AVHRR thermal infrared channels is compared with the in situ measurements. While the quadratic formulation provides a considerable improvement over the older cross product (CPSST) and multichannel (MCSST) algorithms, the SSM/I corrected SST (called the water vapor or WVSST) shows overall smaller errors when compared to both the skin and bulk in situ SST observations. Applied to individual AVHRR images, the WVSST reveals an SST difference pattern (CPSST-WVSST) similar in shape to the water vapor structure while the CPSST-quadratic SST difference appears unrelated in pattern to the nearly coincident water vapor pattern. An application of the WVSST to week-long composites of global area coverage (GAC) AVHRR data demonstrates again the manner in which the WVSST corrects the AVHRR for atmospheric moisture attenuation. By comparison the quadratic SST method underestimates the SST corrections in the lower latitudes and overestimates the SST in th e higher latitudes. Correlations between the AVHRR thermal channel differences and the SSM/I water vapor demonstrate the inability of the channel difference to represent water vapor in the midlatitude and high latitudes during summer. Compared against drifting buoy data the WVSST and the quadratic SST both exhibit the same general behavior with the relatively small differences with the buoy temperatures.

Emery, William J.↗
NASA NTRS1977

Terrestrial environment (Climatic) criteria guidelines for use in aerospace vehicle development, 1977 revision

Guidelines are provided on terrestrial environment data specifically applicable for NASA aerospace vehicles and associated equipment development. Information is included on the general distribution of natural environment extremes in the conterminous United States that may be needed to specify design criteria in the transportation of space vehicle subsystems and components. Atmospheric attenuation was investigated since certain earth orbital experiment missions are influenced by the earth's atmosphere. A summary of climatic extremes for worldwide operational needs is also included. The latest available information on probable climatic extremes is presented with information on atmospheric chemistry, seismic criteria, and on a mathematical model to predict atmospheric dispersion of aerospace engine exhaust cloud rise and growth. Cloud phenomena are also considered.

Kaufman, J. W.↗
NASA NTRS1982

Terrestrial environment (climatic) criteria guidelines for use in aerospace vehicle development

Guidelines on terrestrial environment data specifically applicable for NASA aerospace vehicles and associated equipment development are provided. The general distribution of natural environmental extremes in the conterminous United States that may be needed to specify design criteria in the transportation of space vehicle subsystems and components is considered. Atmospheric attenuation was included, since certain Earth orbital experiment missions are influenced by the Earth's atmosphere. Climatic extremes for worldwide operational needs is also included. Atmospheric chemistry, seismic criteria, and a mathematical model to predict atmospheric dispersion of aerospace engine exhaust cloud rise and growth are discussed. Atmospheric cloud phenomena are considered.

Turner, R. E.↗
NASA NTRS2021

Simulations and case study of X-59 low-booms propagated through measured atmospheric profiles

NASA's X-59 Quiet Supersonic Technology aircraft will soon be used to collect data to support the development of a dose-response relationship between low-boom level and human perception. The X-59's low-boom level will depend on aircraft conditions and trajectory, which can be controlled, and on atmospheric conditions, which cannot be controlled. To assess variability in low-boom levels produced by realistic atmospheres, NASA's PCBoom code was used to simulate propagation of an X-59 nearfield pressure condition through atmospheric profiles measured during NASA's Quiet Supersonic Flights 2018 (QSF18) test. Despite QSF18 lasting only 11 days, substantial weather variability occurred including snow and record high temperatures. A PL range of about 8.5 dB was predicted due to the QSF18 atmospheric variability. These results demonstrate the necessity for X-59's flight condition to be adjusted based on atmospheric conditions in order to achieve desired loudness levels during community surveys. Undertrack booms' Perceived Levels (PL) were predicted not to exceed 75 dB, X-59's target level in a standard atmosphere. Attenuation rate, ray tube area, path length, and other quantities are presented throughout propagation for the atmospheres that produce the loudest and quietest booms. Humidity differences below 15kft were a primary driver of the PL differences.

X-59↗
NASA NTRS1981

Remote sensing of sea surface temperature in the 3.7 micron CO2 band

The main sources of error in remote sensing of sea surface temperature are discussed. The interfering effects of reflected solar radiation, reflected thermal flux, clouds and haze and atmospheric attenuation are examined. The components of measured sea surface radiances, such as clear column radiance, surface emission, atmospheric emission, reflected thermal downward flux, and reflection of solar flux, are analytically presented. The use of the 3.7 micron region window to obtain the radiance to four percent accuracy is discussed. The advantages to be obtained by the use of narrow bandpass channels are assessed.

Chahine, M. T.↗
NASA NTRS1983

NOAA satellite-derived operational sea surface temperature products

The National Oceanic and Atmospheric Administration (NOAA) began processing global measurements of emitted radiation in the 10.5 to 12.5 micron atmospheric window for purposes of deriving weekly composite and mean monthly sea surface temperature fields in the early 1970s. Atmospheric attenuation corrections, begun with empirical means, were accomplished chiefly with the aid of coarser resolution measurements from atmospheric sounders aboard the same polar orbiting spacecraft. Cloud filtering depended heavily upon the use of histogram techniques applied to 11 x 11 arrays of 8 km resolution Scanning Radiometer Infrared (SRIR) data. Details of the SRIR processing for SST are found in a NOAA Technical Memorandum.

Mcclain, E. P.↗
NASA NTRS1993

Terrestrial Environment (Climatic) Criteria Guidelines for Use in Aerospace Vehicle Development, 1993 Revision

Guidelines on terrestrial environment data specifically applicable in the development of design requirements/specifications for NASA aerospace vehicles and associated equipment development are provided. The primary geographic areas encompassed are the John F. Kennedy Space Center, FL; Vandenberg AFB, CA; Edwards AFB, CA; Michoud Assembly Facility, New Orleans, LA; John C. Stennis Space Center, MS; Lyndon B. Johnson Space Center, Houston, TX; and the White Sands Missile Range, NM. In addition, a section was included to provide information on the general distribution of natural environmental extremes in the conterminous United States that may be needed to specify design criteria in the transportation of space vehicle subsystems and components. A summary of climatic extremes for worldwide operational needs is also included. Although not considered as a specific vehicle design criterion, a section on atmospheric attenuation was added since sensors on certain Earth orbital experiment missions are influenced by the Earth's atmosphere. The latest available information on probable climatic extremes is presented and supersedes information presented in TM X-64589, TM X-64757, TM X-78118, and TM-82473. Information is included on atmospheric chemistry, seismic criteria, and on a mathematical model to predict atmospheric dispersion of aerospace engine exhaust cloud rise and growth. There is also a section on atmospheric cloud phenomena. The information is recommended for use in the development of aerospace vehicle and associated equipment design and operational criteria, unless otherwise stated in contract work specifications. The environmental data are primarily limited to information below 90 km.

Johnson, D. L.↗
NASA NTRS1987

Research in millimeter wave techniques

The areas of millimeter wave (MMW) research include atmospheric propagation and radiometry, advanced MMW component design with emphasis on quasi-optical techniques, and the development of MMW receivers, especially those using subharmonic mixers. Calculations of atmospheric attenuation and radiometric antenna temperature were made in the range 100 to 700 GHz, together with measurements of atmospheric antenna temperature near 95 and 183 GHz. Quasi-optical components designed include lenses, mirrors, and wire grid devices, as well as feedhorns for interference with waveguide components. Subharmonic mixers with state-of-the-art performance at 183 GHz were also developed. Each of these areas of research is summarized.

Mcmillan, R. W.↗
NASA NTRS1991

Comparison of OLYMPUS beacon and radiometric attenuation measurements at Blacksburg, Virginia

Measurements of attenuation of the 20 and 30 GHz beacons onboard the OLYMPUS satellite are compared to simultaneous observations of atmospheric attenuation by a multichannel microwave radiometer along the same path. Departures from high correlation between the two measurements are believed to be related to differences in antenna beamwidths. Mean equivalent zenith attenuations derived from the slant path data are compared to zenith observations made at previous locations.

Snider, J. B.↗
NASA NTRS1973

Task 7: Image Enhancement and Advanced Information Extraction Techniques, 1385

The author has identified the following significant results. Atmospheric effects in satellite multispectral scanner data can influence results obtained with either manual image interpretation or computer information extraction techniques. The atmosphere attenuates radiation arriving from the surface and adds an extraneous path radiance component. Initial results of an investigation of atmospheric effects in ERTS-1 data are presented. Empirical analyses of ERTS-1 MSS data and simultaneous airborne MSS underflight data for one frame, along with theoretical calculations of atmospheric effects, are discussed. The effect of limited spatial resolution on the accuracy of information extracted from ERTS-1 data also is important. Problems occur when individual resolution elements contain two or more materials. Results from an initial application of Environmental Research Institute of Michigan techniques for estimating proportions of materials within individual elements are presented and discussed. Very accurate determination of surface areas of small lakes is achieved.

Malila, W. A.↗
NASA NTRS1973

Atmospheric effects in ERTS-1 data, and advanced information extraction techniques

Atmospheric effects in satellite multispectral scanner data can influence results obtained with either manual image interpretation or computer information extraction techniques. The atmosphere attenuates radiation arriving from the surface and adds an extraneous path radiance component. Initial results of an investigation of atmospheric effects in ERTS data are presented. Empirical analyses of ERTS MSS data and simultaneous airborne MSS underflight data for one frame, along with theoretical calculations of atmospheric effects, are discussed. The effect of limited spatial resolution on the accuracy of information extracted from ERTS data also is important. Problems occur when individual resolution elements contain two or more materials. Results from an initial application of ERIM techniques for estimating proportions of materials within individual elements are presented and discussed. Very accurate determination of surface areas of small lakes is achieved.

Malila, W. A.↗
NASA NTRS2020

Validation of a Digital Noise Power Integration Technique for Radiometric Clear Sky Attenuation Estimation at Q-band

This paper presents the validation of a digital signal processing technique that can be used to estimate radiometric sky noise, and hence, atmospheric absorption, within existing digital receivers at little/no additional cost. To demonstrate this, a receiver was constructed that simultaneously records the beacon signal power from the ALPHASAT Aldo Paraboni technology demonstration payload, as well as the integrated noise power in the adjacent band. Calibration from the digital radiometer is performed using tip-curve calibration procedures. Atmospheric fading is then obtained by observing the beacon as well as the radiometric signals. This enables the comparison of fading obtained by the two techniques and provides a means to calibrate the received beacon power level to obtain total atmospheric attenuation. It is shown that for low levels of fading, up to a few dB, the two techniques provide good agreement. This approach can therefore provide a low-cost option for geostationary mmwave satellite channel measurements in the low fading regime, which can be useful in the design and operation of the feeder links in emerging satcom systems.

radiometer↗
NASA NTRS1976

Laser Doppler systems in atmospheric turbulence

The loss of heterodyne signal power for the Marshall Space Flight Center laser Doppler system due to the random changes in the atmospheric index of refraction is investigated. The current status in the physics of low energy laser propagation through turbulent atmosphere is presented. The analysis and approximate evaluation of the loss of the heterodyne signal power due to the atmospheric absorption, scattering, and turbulence are estimated for the conditions of the January 1973 flight tests. Theoretical and experimental signal to noise values are compared. Maximum and minimum values of the atmospheric attenuation over a two way path of 20 km range are calculated as a function of altitude using models of atmosphere, aerosol concentration, and turbulence.

Murty, S. S. R.↗
NASA NTRS1980

A clear-sky spectral solar radiation model for snow-covered mountainous terrain

A clear-sky spectral solar radiation model for direct and diffuse fluxes, combined with topographic calculations from digital terrain data, computes either incident, net, or reflected solar radiation at any point on a snow surface in mountainous terrain. The radiation may be integrated over any wavelength range from 250 to 5000 nm, or over any time step. Atmospheric attenuation parameters are ozone, water vapor, the Angstrom turbidity coefficient and exponent, and the absorptance to reflectance ratio of the atmospheric aerosols. The model derives these, from measurements which may contain both systematic and random errors, by finding the least squares solution to an overdetermined set of nonlinear equations. For calculations over a specified area, it employs table look-up procedures, so that computation speed for the spectral model approaches that for a lumped model. Thus it may be useful as part of a snow surface energy budget calculation over a drainage basin.

Dozier, J.↗
NASA NTRS2008

Terrestrial Environment (Climatic) Criteria Guidelines for use in Aerospace Vehicle Development

This document provides guidelines for the terrestrial environment that are specifically applicable in the development of design requirements/specifications for NASA aerospace vehicles, payloads, and associated ground support equipment. The primary geographic areas encompassed are the John F. Kennedy Space Center, FL; Vandenberg AFB, CA; Edwards AFB, CA; Michoud Assembly Facility, New Orleans, LA; John C. Stennis Space Center, MS; Lyndon B. Johnson Space Center, Houston, TX; George C. Marshall Space Flight Center, Huntsville, AL; and the White Sands Missile Range, NM. This document presents the latest available information on the terrestrial environment applicable to the design and operations of aerospace vehicles and supersedes information presented in NASA-HDBK-1001 and TM X-64589, TM X-64757, TM-78118, TM-82473, and TM-4511. Information is included on winds, atmospheric thermodynamic models, radiation, humidity, precipitation, severe weather, sea state, lightning, atmospheric chemistry, seismic criteria, and a model to predict atmospheric dispersion of aerospace engine exhaust cloud rise and growth. In addition, a section has been included to provide information on the general distribution of natural environmental extremes in the conterminous United States, and world-wide, that may be needed to specify design criteria in the transportation of space vehicle subsystems and components. A section on atmospheric attenuation has been added since measurements by sensors on certain Earth orbital experiment missions are influenced by the Earth s atmosphere. There is also a section on mission analysis, prelaunch monitoring, and flight evaluation as related to the terrestrial environment inputs. The information in these guidelines is recommended for use in the development of aerospace vehicle and related equipment design and associated operational criteria, unless otherwise stated in contract work specifications. The terrestrial environmental data in these guidelines are primarily limited to information below 90 km altitude.

D L Johnson↗
NASA NTRS1969

Millimeter-wave atmospheric loss prediction method

Relationship between atmospheric attenuation and the ground temperature and humidity provides a reference from which changes in temperature and humidity will produce a corresponding atmospheric loss figure. Computer program computes atmospheric loss due to water content, given the measured loss and ground temperature and humidity.

Stelzried, C. T.↗
NASA NTRS1989

Evaluating atmospheric correction models for retrieving surface temperatures from the AVHRR over a tallgrass prairie

The effects of atmospheric attenuation on surface radiative temperatures obtained by the AVHRR over a tallgrass prairie area in the Flint Hills of Kansas are examined. Six atmospheric correction models developed primarily for sea-surface temperature studies are used to test their utility for retrieval of radiative temperatures over the land surface. An uncertainty of + or - 3.0 C was found for the AVHRR data, and used to evaluate the performance of a given model. When the difference between in situ and AVHRR surface temperatures was smaller than the uncertainty, the model was judged to be adequate. Among the six models evaluated, only the NOAA split-window model consistently adjusted the AVHRR surface temperatures within + or - 3.0 C of the in situ measurements.

Cooper, D. I.↗