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Moore, R. K.

Publications and source records attributed to Moore, R. K..

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Simultaneous active and passive microwave response of the earth - The Skylab radscat experiment

The Skylab microwave radiometer-scatterometer experiment S-193 was designed to collect simultaneous information on the radiometric emission and the backscatter from the earth from orbital altitude for the first time. A primary driving force was ascertaining the response from the oceans of both active and passive systems to variations in wind, and the ability of the passive system to aid in calibrating the active system. Numerous overland applications were also explored. Preliminary results of backscatter and emission from sea and atmosphere are shown for hurricane Ava and for two flights across the Gulf of Mexico. The results tend to confirm the most recent theoretical prediction of an approximately square-law relation between scattering coefficient for horizontal polarization and windspeed, with a somewhat smaller dependence for vertical polarization. Overland measurements show that scatterometer signals at 30 deg increase and radiometer signals decrease for terrain that has recently experienced rainfall.

Moore, R. K.↗
NASA NTRS1974

Investigation of radar discrimination of sea ice

The ability of radar to discriminate sea ice types and their thickness was studied. Radar backscatter measurements at 400 MHz (multi-polarization) and 13.3 GHz (VV polarization) obtained from NASA Earth Resources Aircraft Program Mission 126 were analyzed in detail. The scatterometer data were separated into seven categories of sea ice according to age and thickness as interpreted from stereo aerial photographs. The variations of radar backscatter cross-section with sea ice thickness at various angles are presented at the two frequencies. There is a reversal of angular character of radar return from sea ice less than 18 cm thick at the two frequencies. Multi-year ice (sea ice greater than 180 cm thick) gives strongest return at 13.3 GHz. First-year ice (30 cm to 90 cm thick) gives strongest return at 400 MHz. Open water can be differentiated at both the frequencies. Four-polarization 16.5 GHz radar imagery was also obtained. Open water and three categories of sea ice can be identified on the images. The results of the imagery analysis are consistent with the radar scatterometer results.

Parashar, S. K.↗
NASA NTRS1974

Soil moisture detection by Skylab's microwave sensors

Terrain microwave backscatter and emission response to soil moisture variations are investigated using Skylab's 13.9 GHz RADSCAT (Radiometer-Scatterometer) system. Data acquired on June 5, 1973 over a test site in west-central Texas indicates a fair degree of correlation with composite rainfall. The scan mode was cross-track contiguous (CTC) with a pitch of 29.4 deg and no roll offset. Vertical polarization was employed with both radiometer and scatterometer. The composite rainfall was computed according to the flood prediction technique using rainfall data supplied by weather reporting stations.

Ulaby, F. T.↗
NASA NTRS1973

Detection of moisture and moisture related phenomena from Skylab

The author has identified the following significant results. Correlations between the S-194 antenna temperature and soil moisture have been obtained for three sets of data; one for Skylab 2 and two for Skylab 3. The best correlations were obtained for the surface to one inch depth in two cases and for the surface to two inches for the third case. Correlation coefficients for the surface to one inch depth were -0.98, -0.95, and -0.82. The lowest correlation coefficient was obtained with total soil moisture variations less than 4% across the test site.

Eagleman, J. R.↗
NASA NTRS1973

Preliminary report on Skylab S-193 Radscat measurements of Hurricane Ava

The author has identified the following significant results. The Skylab RADSCAT instrument S-193 was operated on 6 June 1973 while the spacecraft flew past Hurricane Ava in the eastern Pacific Ocean. Scatterometer returns at all polarizations and radiometer measurements were obtained from a section through the storm with winds up to 48 knots at 52 deg incident angle and 35 knots at 45.5 deg incident angle. These first hurricane scatterometer measurements indicate reasonable correlation between wind speed and backscatter, with horizontal response much stronger than the vertical response at 52 deg. Each of the sections through the hurricane contains an as yet unexplained dip in cross section at a point 200 to 300 km prior to passing the eye. The response at a point where the radiometer signal's dramatic increase indicates strong rain is also accompanied by a strong increase in the backscattered signal. No attempt has been made to make a thorough correlation of radiometric response with wind speed, but the atmospheric contribution to the radiometer signal is quite apparent.

Pierson, W. J., Jr.↗
NASA NTRS1973

Detection of moisture and moisture related phenomena from Skylab

The author has identified the following significant results. This is a preliminary report on the ability to detect soil moisture variation from the two different sensors on board Skylab. Initial investigations of S190A and Sl94 Skylab data and ground truth has indicated the following significant results. (1) There was a decrease in Sl94 antenna temperature from NW to SE across the Texas test site. (2) Soil moisture increases were measured from NW to SE across the test site. (3) There was a general increase in precipitation distribution and radar echoes from NW to SE across the site for the few days prior to measurements. This was consistent with the soil moisture measurements and gives more complete coverage of the site. (4) There are distinct variations in soil textures over the test site. This affects the moisture holding capacity of soils and must be considered. (5) Strong correlation coefficients were obtained between S194 antenna temperature and soil moisutre content. As the antenna temperature decreases soil moisture increases. (6) The Sl94 antenna temperature correlated best with soil mositure content in the upper two inches of the soil. A correlation coefficient of .988 was obtained. (7) Sl90A photographs in the red-infrared region were shown to be useful for identification of Abilene clay loam and for determining the distribution of this soil type.

Eagleman, J. R.↗
NASA NTRS1973

Radar spectral measurements of vegetation

Spectral data of 4-8 GHz radar backscatter were gathered during the 1972 growing season at look angles between 0 and 70 deg and for all four possible polarization linear combinations. The data covers four crop types (corn, milo, alfalfa, and soybeans) and a wide range of soil moisture content. To insure statistical representation of the results, measurements were conducted over 128 fields corresponding to a total of about 40,000 data points. The use of spectral response signatures to separate different crop types and to separate healthy corn from blighted corn was investigated.

Ulaby, F. T.↗
NASA NTRS1972

Radar signature and systems studies at Kansas University

The radar signature and systems studies described have concentrated in two areas: octave bandwidths radar spectrometry using a truck-mounted system, and scatterometry using primarily the 13.3 GHz system on aircraft. In addition, the results of the experiments to date have been synthesized into a pair of representative designs for spacecraft radar systems: one for small spacecraft and one for large spacecraft.

Moore, R. K.↗
NASA NTRS1972

The extrapolation of laboratory and aircraft radar sea return data to spacecraft altitudes

Laboratory measurements show that the spectra of capillary waves grow with wind speed over six orders of magnitude. The scatter in the data can be partially understood and predicted from a combination of turbulence theory, radar theory, and the small sample theory of statistical inference. When these results are applied to a prediction of the sea return values to be obtained by S193 on Skylab, it can be shown that the size of the illuminated patch effectively averages out the horizontal scales of gustiness, so that the measurement will correspond to the synoptic scale wind.

Pierson, W. J.↗
NASA NTRS1972

Global oceanic microwave anemometry - A planned space verification experiment.

Recent observations of the wind sensitivity of oceanic backscatter and temperature measurements are shown to have made it possible to design an experiment for verifying the potential use of an operational global satellite anemometer. The experiment is to be conducted with the Skylab in 1973, and its success may lead to the design and flight of an operational microwave scatterometer-radiometer instrument on a small satellite flying in a polar orbit sometime in the late 1970's.

Moore, R. K.↗
NASA NTRS1971

Imaging radars for geoscience use

Side-looking airborne radars and image recording scanners design for geoscience applications, discussing gray scale improvement, multispectral sensing, target discrimination, etc

Moore, R. K.↗
NASA NTRS1971

Scattering from rough surfaces

Electromagnetic wave scattering from rough surfaces, discussing radar return differences for different polarizations

Moore, R. K.↗