Weather System Follow-on - Microwave (WSF-M) On-Orbit Calibration/Validation

The Weather System Follow-on – Microwave (WSF-M) is a Department of Defense (DoD) next- generation, operational, low earth orbit, environmental satellite system that provides space-based terrestrial environmental sensing capabilities. The WSF-M was successfully launched on 11 April,2024 to a polar sun-synchronous orbit at a nominal altitude of 833 km with Local Time Ascending Node (LTAN) of 1800 hours. The WSF-M primary payload, Microwave Imager (MWI), is a conically scanning microwave radiometer, operating at 10.85, 18.85, 23.8, 37 and 89 GHz. It has a total of 17 channels with fully polarimetric digital channels at 10.85, 18.85 and 36.75 GHz and analog channels at 23.8, 37.3 and 89 GHz, which enables to derive Ocean Surface Vector Winds (OSVW), Tropical Cyclone Intensity (TCI), snow depth, sea ice characterization, soil moisture and other environmental data products.

Led by WSF-M Program Office, an intensive Calibration and Validation (Cal/Val) has been conducted to ensure 1) accuracies of on-orbit MWI radiometric performance and geolocation; and 2) the performance of MWI algorithms and data products to meet mission requirements. The WSF-M Cal/Val team leverages Cal/Val experiences and approaches from successful heritage microwave sensors, such as Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager/Sounder (SSMIS), Coriolis/WindSat, and Global Precipitation Measurement (GPM) Microwave Imager (GMI). This paper presents Cal/Val results and discusses various WSF-M Cal/Val activities, including calibration maneuvers, assessment of radiometric and geolocation performance, evaluation of on-orbit MWI sensor characteristics, and updates to algorithms.