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At least 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Seasat-A opens new phase in earth observations

The data output of the Seasat-A, the first satellite designed specifically for oceanographic observation, is described. Wave height and direction, ice distribution, surface wind speed and direction, ocean-surface temperature, and atmospheric water content will be monitored by the satellite. Imaging radar, microwave scatterometer, microwave radiometer and visual and infrared radiometer experiments are included in the Seasat-A observing program. Two types of orbits have been developed: a near-repeat cycle of three days, and a near-repeat cycle of 25 days. Both orbit types offer fine coverage (18.5 km crossing separations) of the earth. Synthetic aperture radar data on computer-compatible tapes and geophysical data records available through the Seasat-A mission are described.

Cutting, E.↗
NASA NTRS1977

Infrared and millimeter wave techniques for the Cosmic Background Explorer Satellite

The Cosmic Background Explorer Satellite will employ infrared and microwave techniques to gain information about the very early universe. Three instruments will cover the spectral range from 8 microns to 13 mm, determining both the spectrum and angular distribution of the large scale background radiation fields. A cryogenic polarizing Michelson interferometric spectrometer will measure the spectrum of the 3 deg K relic radiation from the big bang with precision. Four differential microwave radiometers will map the sky from 23 to 90 GHz in a search for anisotropy of the universe. A broadband cryogenic IR photometer will map zodiacal dust emission, galactic dust, and an extragalactic residual component.

Mather, J. C.↗
NASA NTRS1978

Photovoltaic power-system options for the manned space construction base

The function of the proposed manned Space Construction Base (SCB) is to provide a permanent manned orbital facility for the construction and operation of a variety of space experiments, ranging from a space-processing development to on-orbit-constructed microwave radiometers and antennas. A typical SCB system might reach initial operational capability in low earth orbit in 1985, have a 10-year mission duration, and have an initial power requirement of 50 kWe. A summary of the requirements imposed by the SCB on the electrical power system (EPS) is presented in a table. Attention is given to EPS options, baseline power platform system operations, an energy storage system evaluation, advanced-technology NiCd batteries and lifetime, and orbital buildup operations.

Mckhann, G. G.↗
NASA NTRS1978

A statistical technique for determining rainfall over land employing Nimbus-6 ESMR measurements

At 37 GHz, the frequency at which the Nimbus 6 Electrically Scanning Microwave Radiometer (ESMR 6) measures upwelling radiance, it was shown theoretically that the atmospheric scattering and the relative independence on electromagnetic polarization of the radiances emerging from hydrometers make it possible to monitor remotely active rainfall over land. In order to verify experimentally these theoretical findings and to develop an algorithm to monitor rainfall over land, the digitized ESMR 6 measurements were examined statistically. Horizontally and vertically polarized brightness temperature pairs (TH, TV) from ESMR 6 were sampled for areas of rainfall over land as determined from the rain recording stations and the WSR 57 radar, and areas of wet and dry ground (whose thermodynamic temperatures were greater than 5 C) over the Southeastern United States. These three categories of brightness temperatures were found to be significantly different in the sense that the chances that the mean vectors of any two populations coincided were less than 1 in 100.

Rodgers, E.↗
NASA NTRS1977

Advanced technology requirements for large space structures. Part 5: Atlas program requirements

The results of a special study which identifies and assigns priorities to technology requirements needed to accomplish a particular scenario of future large area space systems are described. Proposed future systems analyzed for technology requirements included large Electronic Mail, Microwave Radiometer, and Radar Surveillance Satellites. Twenty technology areas were identified as requirements to develop the proposed space systems.

Katz, E.↗
NASA NTRS1977

Latent heat calculations and their relationship to tropical cyclone intensity

Data from the Nimbus-5 electrically scanning microwave radiometer (ESMR) were used to calculate total storm latent heat release (LHR) and other precipitation parameters for over 100 satellite observations of Pacific Ocean tropical cyclones. The data are useful in determining the rainfall characteristics of these storms and appear to be potentially useful in monitoring them.

Adler, R. F.↗
NASA NTRS1977

Microwave radiometric measurements of sea-surface parameters

A technique to remotely measure sea-surface temperature and salinity (for concentrations greater than 5 parts-per-thousand) with accuracies of 1 C and 1 part-per-thousand, respectively, was demonstrated with a two-frequency microwave radiometer system.

Kendall, B. M.↗
NASA NTRS1979

An objective method for forecasting tropical cyclone intensity and motion using Nimbus-5 ESMR measurements and non-satellite derived descriptors

An empirical analysis program, based on finding an optimal representation of the data was applied to 120 observations of 29 1973 and 1974 North Pacific tropical cyclones. Each observation consists of a field of Nimbus-5 Electrically Scanning Microwave Radiometer radiation measurements at 267 grid points covering and surrounding the tropical cyclone plus nine other non-satellite derived discriptors. Forecast algorithms to estimate storm intensity and motion at 12, 24, 48, and 72 hours after each observation were developed using an independent eigen screening analysis. These algorithms were based on best track data. Independent testing of these algorithms showed that the performance of most of these algorithms were better than persistence and the algorithms forecasting 24, 48, and 72 hour maximum wind speed were better than those made operationally by the Joint Typhoon Warning Center for 1973 and 1974 that did not use best track data.

Hunter, H. E.↗
NASA NTRS1979

Periodic variations of precipitation in the tropical Atlantic Ocean

Statistical analysis of the satellite-borne Electrically Scanning Microwave Radiometer data in the tropical Atlantic region reveals that the rainfall near local noon is higher both in frequency of occurrence and intensity than the rainfall in the same area near local midnight. Another striking feature that stands out from the analysis is an oscillation with a period of 3.3. days in rainfall occurrence and intensity. This periodicty is consistent with easterly waves traveling from the African continent to the region under study.

Rao, M. S. V.↗
NASA NTRS1979

Passive microwave applications to snowpack monitoring using satellite data

Nimbus-5 Electrically Scanned Microwave Radiometer data were analyzed for the fall of 1975 and winter and summer of 1976 over the Arctic Coastal Plain of Alaska to determine the applicability of those data to snowpack monitoring. It was found that when the snow depth remained constant at 12.7 cm, the brightness temperatures T sub B varied with air temperature. During April and May the production of ice lenses and layers within the snow, and possibly wet ground beneath the snow contribute to the T sub B variations also. Comparison of March T sub B values of three areas with the same (12.7 cm) snow depth showed that air temperature is the predominant factor controlling the T sub B differences among the three areas, but underlying surface conditions and individual snowpack characteristics are also significant factors.

Hall, D. K.↗
NASA NTRS1977

Sea-surface temperature and salinity mapping from remote microwave radiometric measurements of brightness temperature

A technique to measure remotely sea surface temperature and salinity was demonstrated with a dual frequency microwave radiometer system. Accuracies in temperature of 1 C and in salinity of part thousand for salinity greater than 5 parts per thousand were attained after correcting for the influence of extraterrestrial background radiation, atmospheric radiation and attenuation, sea-surface roughness, and antenna beamwidth. The radiometers, operating at 1.43 and 2.65 GHz, comprise a third-generation system using null balancing and feedback noise injection. Flight measurements from an aircraft at an altitude of 1.4 km over the lower Chesapeake Bay and coastal areas of the Atlantic Ocean resulted in contour maps of sea-surface temperature and salinity with a spatial resolution of 0.5 km.

Hans-Juergen, C. B.↗
NASA NTRS1978

Structural development of the Nimbus-G/Seasat-A SMMR graphite epoxy antenna reflector

Specific details concerning the structural design, analysis, fabrication and testing of the Nimbus-G/Seasat-A Scanning Multichannel Microwave Radiometer (SMMR) are presented. Design requirements are illustrated and trade-off considerations discussed in terms of flight project requirements. It is shown that the application of graphite/epoxy material results in a lightweight, stiff, thermally stable antenna structure fully qualified for mission application.

Knoell, A.↗
NASA NTRS1978

International Symposium on Remote Sensing of Environment, 12th, Manila, Philippines, April 20-26, 1978, Proceedings. Volumes 1, 2 & 3

The papers outline the remote sensing activities being carried out in a number of countries throughout the world, and present details on a variety of individual projects. Topics studied include a worldwide approach to remote sensing and mineral exploration, a land use information system based on statistical inference, acoustic radar and remote sensing in the boundary layer, procedure for land-use analysis in developing countries, an airborne geochemical system, remote sensing of snowpack with microwave radiometers for hydrologic applications, wheat production forecasts based on Landsat data, airborne lidar aerosol measurements over the U.S. and Europe, Landsat inventory of agricultural and forest resources in Bangladesh, application of satellite imagery to flood plain mapping in Thailand, and vegetation mapping of Nigeria from radar.

Source record↗
NASA NTRS1979

Applications of remote sensing for water quality and biological measurements in coastal waters

Potential applications of remote sensing technology to the study of coastal marine environments are reviewed, emphasizing water quality and biological measurements. Parameters measurable by airborne or spaceborne remote sensors include particulates, measured by visual or multispectral photography, chlorophyll a, measured by the Ocean Color Scanner or Coastal Zone Color Scanner, temperature distributions, by IR or microwave sensors, and salinity, by means of microwave radiometers. Research projects in which wide area synoptic or repetitive remote sensing can make a major contribution include the study of estuarine and continental shelf sediment transport dynamics, marine pollutant transport, marine phytoplankton dynamics and ocean fronts.

Johnson, R. W.↗
NASA NTRS1979

Seasat low-rate data system

The Seasat low-rate data system, an end-to-end data-processing and data-distribution system for the four low-rate sensors (radar altimeter, Seasat-A scatterometer system, scanning multichannel microwave radiometer, and visible and infrared radiometer) carried aboard the satellite, is discussed. The function of the distributed, nonreal-time, magnetic-tape system is to apply necessary calibrations, corrections, and conversions to yield geophysically meaningful products from raw telemetry data. The algorithms developed for processing data from the different sensors are described, together with the data catalogs compiled.

Brown, J. W.↗
NASA NTRS1979

The effect of wind on the microwave emission from the ocean's surface at 37 GHz

The microwave brightness temperature measurements from the electrically scanned microwave radiometer (frequency = 37 GHz) are compared with oceanic wind measurements from data buoys. It is shown that the brightness temperature can be manipulated to yield a measure of the surface roughening, which can be very well accounted for by a simple geometric optics model. The data of Hollinger (1971) at 1.4, 8, 36, and 19.34 GHz were similarly manipulated and shown to require a surface with less slope variance than that predicted by the Cox and Munk (1955) optical measurements. It is also shown that the surface may be treated as isotropic to an accuracy equivalent to the roughening produced by a 2-m/s wind speed increment.

Wilheit, T. T.↗
NASA NTRS1979

New space initiatives through large generic structures

New possibilities in satellite communications, surveillance, and orbital experimentation provided by the capability to construct and deploy Large Space Structures (LSS) are presented. The advent of the Shuttle will allow deployment of larger antennas with much larger gain sizes, noting new applications in communications, radiometry, and radar in frequencies from 0.24 to 14 GHz. Applications in multi-beam communication which can hold spot sizes on the ground down to 30 miles in diameter, new applications of the large aperture radar antenna, and estimates of soil moisture by the microwave radiometer are discussed. The Solar Power Satellite consisting of a large solar collector orbiting the earth at geosynchronous altitude over the equator which requires ability to construct LSS in space is described, noting the design of solar cells and materials of construction, including graphite composites and aluminum alloys. Space construction procedures and equipment are considered, noting that the most likely procedure would deliver the subsystems to orbit separately, and then construct the spacecraft on-orbit and assemble the satellite.

Johnson, R. W.↗
NASA NTRS1979

Theory and experiment for passive microwave remote sensing of snowpacks

Both the theory and experiment for the passive remote sensing of snow with microwave radiometers have been studied. The volume scattering effects of snow are accounted for by incorporating Mie scattering theory into a radiative transfer model. The theory is applied to the interpretation of experimental data obtained from various snow measurements. The spectral and angular dependences of the brightness temperatures are illustrated and show good agreement between the theory and experiment. Brightness temperatures as a function of snow depths are also interpreted and discussed. It is observed that as the snow depth increases, the brightness temperature increases when the subsurface is an aluminum plate due to the fact that the plate is cold and snow absorption induces a brightening effect and the brightness temperature decreases when the subsurface is soil due to the fact that snow scattering induces darkening effects.

Kong, J. A.↗