Signatures of Sentinel-1 Radar and SMAP Radiometer Depending on the Temperature of Frozen Arctic Soil in the Cooling and Heating Process of the Active Layer

In this paper, the results of radiothermal and radar remote sensing of several Arctic tundra test sites were investigated to establish the dependences of the reflectivity and backscattering coefficient on soil temperature. The brightness temperature and backscattering coefficient were measured by a SMAP radiometer (1.4GHz) and Sentinel-1 radar (5.4GHz) over areas near to Franklin Bluffs weather station in the North Slope of Alaska and Isachsen weather station on Ellef Ringnes Island respectively. It has been experimentally and theoretically shown that between the surface soil temperature measured by weather stations in the period 2015-2016 and the reflectivity or backscattering coefficient there is a strong correlation relationship no worse than 0.68. In addition, in the range of soil surface temperature changes from -30°C to 0°C, the variations in the backscattering coefficient and reflectivity are about 4 dB for both test sites. This study contributes to further understanding the processes of microwave emission and scattering of frozen Arctic soils that is pertinent to developing new remote sensing algorithms for the permafrost region.