Sensitivity Analysis of CYGNSS derived Radar Reflectivity for Soil Moisture Retrieval over India: Initial Results

This paper demonstrates the relationship of surface radar reflectivity derived from Cyclone Global Navigation Satellite System (CYGNSS) measurements with the Soil Moisture (SM) derived from Soil Moisture Active Passive (SMAP) over India. CYGNSS is an operational eight-satellite constellation, each with a Delay Doppler Mapping Instrument (DDMI) for deriving wind speed in tropical cyclones over oceans. However, these reflections from the land surface, acquired by the DDMI instrument, can also be used to retrieve Soil Moisture (SM). Surface radar reflectivity was derived from Delay Doppler Map (DDM) at specular points generated by CYGNSS measurements as coherent specular reflections over land using radar range equations. From the analysis carried out for selected data sets, a strong linear relationship between CYGNSS derived radar reflectivity and SMAP derived SM has been demonstrated.