3km SMAP/CYGNSS Soil Moisture

3km SMAP/CYGNSS soil moisture is a downscaled Soil Moisture Active Passive (SMAP) soil moisture product. We downscaled 9km SMAP enhanced brightness temperatures by merging them with L-band Cyclone Global Navigation Satellite System (CYGNSS) reflectivity data, using a modified version of the SMAP active-passive brightness temperature algorithm. We then calculated 3km SMAP/CYGNSS soil moisture using the resulting 3km SMAP/CYGNSS brightness temperatures and the SMAP single channel vertically-polarized soil moisture algorithm (SCA-V). To remedy the sparse daily coverage of CYGNSS data at 3km spatial resolution, we used spatially interpolated CYGNSS data to downscale SMAP soil moisture. 3km interpolated SMAP/CYGNSS soil moisture has a repeat period of ~2-3 days.