Evaluating the affect of seasonal soil moisture and vegetation change on C-Band SAR backscatter over corn fields in SW Ontario

Abstract

Soil moisture estimates using C-band SAR over agricultural fields have a backscatter signal that saturates early in the growing season, especially at high incidence angles. This research derives these saturation points using a statistical approach on corn fields just south of Elora, Ontario using RADARSAT-2 overpassess with incidence angles ≥45°. Vegetation water content (VWC) and backscatter are segmented before and after saturation, as well as overall to assess their relationship. These saturation points are used to segment in-situ soil moisture and backscatter. The saturation points of VWC are 0.14, 0.17, and 1.69 kg m-2 for HH, HV, and VV polarizations respectively. The results indicate that VWC dominates the backscatter until saturation but that soil moisture is always a contributing factor to the backscatter signal. VV exhibited the latest saturation point and the correlations it exhibited with VWC and soil moisture were unexpected and require further investigation.