Accession Number : ADP006381

Title :   Modeling and Measuring Millimeter-Wave Scattering from Snow-Covered Terrain,

Corporate Author : MICHIGAN UNIV ANN ARBOR DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE

Personal Author(s) : Ulaby, Fawwaz T. ; Kuga, Yasuo ; Austin, Richard

Report Date : SEP 1991

Pagination or Media Count : 11

Abstract : A radiative transfer model was developed for characterizing radar backscatter from snow- covered ground at millimeter wave-lengths. The model was used to evaluate the radar response to incidence angle, snow depth, snow surface roughness, and snow liquid water content, for both like- and cross-polarization configurations. The model behavior was compared with experimental observations made at 35, 95, and 140 GHz, including observations over diurnal cycles. The experimental data were acquired during the 1989 and 1990 winter seasons in Michigan using a truck-mounted millimeter-wave scatterometer system capable of observing the ground surface over a wide range of incidence angles for all linear combinations of transmit and receive antenna polarizations. Comparison of the measured data with model calculations revealed excellent agreement for dry snow as well as when the surface layer of the snowpack was wet. However, when the surface layer was dry and lower layers were wet, the model results were inconsistent with the radar observations. To deal with tile general case wherein the liquid water content exhibits a nonlinear profile with depth, a hybrid numerical-first order solution of the radiative transfer model was developed. This hybrid model provided excellent agreement with the diurnal observations of radar backscatter.

Descriptors :   *RADAR, *RADIATIVE TRANSFER, *SNOW, *ANGLE OF INCIDENCE, AGREEMENTS, ANGLES, ANTENNAS, BEHAVIOR, COMPARISON, CONFIGURATIONS, CROSS POLARIZATION, CYCLES, DEPTH, EXPERIMENTAL DATA, LAYERS, LIQUIDS, MICHIGAN, MILLIMETER WAVES, MODELS, POLARIZATION, PROFILES, RESPONSE, ROUGHNESS, SCATTEROMETERS, SEASONS, SURFACE ROUGHNESS, TILES, TRANSFER, TRUCKS, WATER, WINTER, BACKSCATTERING, DIELECTRIC PROPERTIES, SNOW COVER, ICE, TARGET DETECTION, MILITARY EQUIPMENT.

Subject Categories : Active & Passive Radar Detection & Equipment
      Snow, Ice and Permafrost

Distribution Statement : APPROVED FOR PUBLIC RELEASE