Soil Moisture Determination: Experiments with Passive Microwave Radiometers

Long term observational programs have been followed in 1977 and 1978, on the determination of the relationship between emissivity and soil moisture on 3 test sites, representing 3 soil types. Five radiometers, whose frequencies are centered at 36, 21, 10.5, 4.9 and 1.8 GHz, were used. Interpretation of measurment follows 3 ways: • analysis of the radiometers response versus scan angle • factorial analysis of correspondances and clustering analysis • analysis of emissivity variation versus soil moisture content: in this latest case a non-linear function was fitted on the datas and could be partially explained. Besides, an experiment was conducted to determine the real penetration depth in a heavy soil.