Analysis of COSMIC-2 radio occultation observations and atmospheric profiles

Objectives  COSMIC-2 constellation, as the follow-on mission of COSMIC (Constellation Observing System for Meteorology Ionosphere and Climate), has refined the radio occultation (RO) payloads with multi-GNSS signals support and high-gain beam-forming RO antennas, which will improve both the quantity and quality of the RO observations.   Methods  In this research, we focused on the input observations and output profiles of the RO retrieval, evaluating the raw observations from both precise orbit determination (POD) and RO antennas, and accessing the atmospheric profiles using ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis products as reference.   Results  The results show that the L1 signal-to-noise ratio (SNR) on COSMIC-2 POD antennas were mostly above 45dB, and the corresponding pseudo-range multipath standard deviation errors were between 0.2m and 0.4m. The SNR values on RO antenna were significantly improved from less than 700v/v on COSMIC to 1200v/v on COSMIC-2, and both the GLONASS and GPS RO profiles show good consistency with ECMWF re-analysis products.   Conclusions  It can be concluded that the updated COSMIC-2 RO payloads not only increasing the profile number, and also the quality of RO profiles had been significantly improved with high-gain antennas, which will provide important observations for atmospheric scientific research.