Hans-Peter Marshall

NASA Cold Land Processes Experiment (CLPX 2002/03): Local Scale Observation Site

Abstract The local scale observation site (LSOS) is the smallest study site (0.8 ha) of the 2002/03 Cold Land Processes Experiment (CLPX) and is located within the Fraser mesocell study area. It was the most intensively measured site of the CLPX, and measurements here had the greatest temporal component of all CLPX sites. Measurements made at the LSOS were designed to produce a comprehensive assessment of the snow, soil, and vegetation characteristics viewed by the ground-based remote sensing instruments. The objective of the ground-based microwave remote sensing was to collect time series of active and passive microwave spectral signatures over snow, soil, and forest, which is coincident with the intensive physical characterization of these features. Ground-based remote sensing instruments included frequency modulated continuous wave (FMCW) radars operating over multiple microwave bandwidths; the Ground-Based Microwave Radiometer (GBMR-7) operating at channels 18.7, 23.8, 36.5, and 89 GHz; and in 2003, a...

Radar signature of disturbed soil for mine detection

A potential strategy for wide area airborne mine/minefield detection is to identify localized areas of soil that have been disturbed due to mine emplacement amidst the undisturbed soil. Disturbed and undisturbed soils are rough in varying degrees and this roughness affects the backscattering behavior at the microwave frequencies. We investigated the feasibility of using high-frequency radar (8-18 GHz) backscatter measurements to detect the residual surface disturbances caused by recent mine emplacement. Radar backscatter measurements from recently buried landmines were obtained at a government minefield data collection site. Case studies of radar backscatter from landmines buried in dirt and gravel for varying incident angles are presented. These results demonstrate that the surface roughness contrast between disturbed and undisturbed soils can be exploited to assist in mine detection operations. The maximum radar backscatter contrast between the disturbed and undisturbed soils was observed at normal incidence. The minimum contrast (radar backscatter crossover angle) occurred between 15 and 30 degree incident angles. These experimental results are shown to be consistent with rough surface scattering assumptions.