Forward and Backward Full-Pol Scattering Analysis using SMAP Datasets

Over the past two decades, there has been a growing trend in the utilization of bistatic radar configurations for remote sensing using Signals-of-Opportunity (SoOp), such as Global Navigation Satellite System - Reflectometry (GNSS-R). This GNSS-R forward configuration is dominated by scattering mechanisms different from the more standard monostatic backward radar configuration. The forward scattering measurement provides insights into regions where backscatter is minimal or dominated by the double bounce effect of vegetation. The Soil Moisture Active Passive (SMAP) consists of a L-band radiometer and radar. After commissioning, the SMAP radar malfunctioned, and it was reconfigured to measure GPS L2C signals instead. The radar repurposing offers a unique opportunity to compare both radar measurements (SMAP radar), and GNSS-R data (SMAP-R) obtained by the same platform, with the same antenna, incident angle, and at a very similar frequency. This study provides a qualitative and quantitative analysis of the relationship between measured full-polarization forward and 3-pol (HH, VV and HV) backward scattering, offering comparisons with ancillary geophysical measurements over 3 distinct areas, with varying environments including dense forests and deserts.