Measurement and Modeling of Multi-Frequency Microwave Emission of Soil Freezing and Thawing Processes

A ground-based microwave remote sensing experiment was carried out in 2016 using a multi-frequency microwave radiometer at L, C and X bands (1.4, 6.925 and 10.65 GHz). The aim of the experiment was to explore multi-frequency microwave emission characteristics of the soil freeze-thaw process for model and algorithm development for the future Water Cycle Observation Mission (WCOM). Measurements were carried out on pastureland in Chengde, Hebei Province, which belongs to seasonally frozen ground of China. Together with brightness temperature, soil temperature and soil moisture profiles, the frost depth, and meteorological observations were synchronously collected. Measurement and modelling results show that microwave brightness temperature has different responses to soil freezing and thawing process at different frequencies.