COSMIC-2 soundings impacts on a RO-based NOAA microwave satellite data quality monitoring system

The Constellation Observing System for Meteorology, Ionosphere and Climate-2/Formosa Satellite Mission 7 (COSMIC-2) Global Navigation Satellite System (GNSS) Radio Occultation (RO) constellation is the follow-on to the highly successful COSMIC-1 program. The GNSS RO atmospheric soundings have historically been used to generate Community Radiative Transfer Model simulated background (B) microwave (MW) brightness temperature data needed to monitor NOAA operational MW sounding instrument observed (O) antenna temperature (Ta) product quality. This study is motivated by the need to determine the impact of COSMIC-2 RO soundings on this critical long-term monitoring capability. This study is based on individual MW sensor O-B Ta bias (∆ T a ) statistics and "double-difference" inter-sensor Ta bias (δ T a ) statistics for two time periods. Time Period 1 (TP1—May 1, 2017, to September 30, 2019) exclusively uses COSMIC-1 and Korea Multi-Purpose Satellite-5 soundings, while Time Period 2 (TP2—October 1, 2019, to December 31, 2020) expands the analysis with COSMIC-2 soundings. The TP1 and TP2 ∆T a statistics comparisons indicate COSMIC-2 data population augmentation and latitudinal distribution impact the MW sounder performance monitoring tool transition from TP1 to TP2. COSMIC-2 competently supports long-term MW individual sensor and inter-sensor product monitoring for MW radiometer channels with weighting functions that peak between 8 and 30 km. Individual sensor ∆T a monitoring for other microwave channels that depend on COSMIC-2 data below 8 km and from 30 km to 60 has limitations, but these limitations are shown not to inhibit critical δT a monitoring.