Microwave Radiometer and Scatterometer Measurements of Vegetation (Maetningar av Vegetation med Mikrovags-Radiometer och Scatterometer)

摘要

The report describes microwave measurements of vegetation, performed in Switzerland in May-June 1986 and July 1987 with two instruments of the Institute of Applied Physics, University of Bern. These include radiometers between 1.5 and 94 GHz, and a noise scatterometer with channels between 1.5 and 11 GHz. The purpose was to test some less-established methods for microwave studies of vegetation. One approach was to use the sky as a background for transmission measurements with radiometers, another was to investigate simple vegetation constituents such as single plant leaves, tree twigs or trunks. The transmission and reflection of leaves of poplar, Alpine dock and mullein, and twigs of spruce and birch have been investigated with radiometers at 10.4, 21, 35 and 94 GHz. Measurements were repeated with time to study the effects of drying. Leaf modeling with a plane parallel dielectric sheet has been attempted and compared with dielectric mixing models. The transmission through forest type vegetation was determined with radiometer measurements between 2.5 and 11 GHz with sky background. The specific attenuation has been estimated using a plane parallel sheet model for the vegetation. Scatterometer measurements were made towards young fir bushes and a spruce trunk. The reflection in the trunk has been analyzed by geometrical optics and a dielectric model.