NISAR Soil Moisture retrievals using the Time-Series Ratio Algorithm

The NISAR mission will provide global data sets of Earth land surface dynamics that are critical to multiple Earth Science disciplines including observations of ecosystem carbon and water cycles. Soil moisture is a surface hydrosphere state variable and plays a key role in global terrestrial hydrology.  It controls the partitioning of water and energy fluxes at the land surface.  NISAR's L-band SAR backscatter measurements are similar to those planned for the L-band radar of the Soil Moisture Active/Passive (SMAP) mission, although at much finer spatial resolution.

NISAR soil moisture using a time-series ratio algotrithm is currently being developed. The final NISAR soil moisture product will have 200m spatial resolution with 12-day exact revisit time. A time-series ratio algorithm was implemented using UAVSAR (SMAPVEX12 field experiment) and SMAP radar observations. In this paper, the performance of the time series ratio algorithm was assessed using in situ observations. Performance of the soil moisture retrieval algorithm was also assessed for dual polarization and quad-polarization observations modes.