Analysis of Permafrost Active Layer Soil Heterogeneity in Support of Radar Retrievals

In this paper, we characterize vertical dielectric profile of permafrost soils to account for different soil horizons (or-ganic/mineral/permafrost) and seasonal variations of soil moisture and freeze/thaw state. The in-situ soil profile measurements from SoilSCAPE sites in Alaska and field observations are analyzed. We proposed three profile functions (i.e., constant, second-order polynomial, and exponential) to be used for modeling permafrost soils in radar retrievals. Constant profile has the lowest errors between in-situ and fitted profiles as well as between measured and simulated radar backscatter values. However, constant profile can only represent sharp transitions across different soil boundaries, whereas the exponential function can describe more realistic transitions at both ends of the active layer while having similar errors as constant profile. Second-order polynomial is only suitable for root-zone soil moisture (RZSM) in non-permafrost regions as permafrost soils have multiple abrupt changes throughout the soil column.