Spaceborne radar monitoring of soil freezing/thawing processes in the Arctic tundra

In this article, the possibility of measuring the average temperature in the active topsoil of the Arctic tundra from the temperature dependence of the radar backscattering coefficient is theoretically studied. The radar backscattering coefficient is simulated by the small perturbation method at a frequency of 1.26 GHz of radars placed onboard ALOS-2 and SMAP satellites. In simulation, the soil density, surface roughness, and temperature and moisture profiles measured in situ at the biosphere station Franklin Bluffs, Alaska (69A degrees 39' N, 148A degrees 43' W), from August 1, 2000 to July 1, 2001 were used. The soil permittivity was calculated for the generalized temperature-dependent refractive mixing dielectric model for organic rich soil whose sample was taken on the Alaska North Slope (68A degrees 38'N, 149A degrees 35'W). This model allows the complex dielectric constant of moist thawed and frozen soil to be calculated at temperatures in the range from -30A degrees D to +25A degrees D. It is demonstrated that the radar backscattering coefficient is correlated with the topsoil temperature with the error less than 5.7A degrees D during the entire period of freezing and thawing.