Support to Global Navigation Satellite System Radio Occultation Research and Development to STAR, OPPA and OSAAP

(NOAA Collaborators:Shu-peng Ho)

Radio Occultation (RO) complements microwave and infrared sounders by providing information on the temperature, water vapor and pressure with high accuracy and precision and high vertical resolution. RO-retrieved bending angle and atmosphere profiles can be directly assimilated into the weather forecasting model without bias correction. RO observations have shown a significant positive impact on global numerical weather prediction (NWP) through data assimilation since the launch of COSMIC. COSMIC-2, was successfully launched on June 24, 2019 as the COSMIC follow-on constellation. In the era of Global Navigation Satellite System (GNSS) consisting of GPS, GLONASS and Galileo satellites, new generation of RO satellite, e.g. COSMIC-2, receive navigation signal from multiple GNSS satellites in multiple bands. Such design enhances RO signal quality and increases the number of successful RO retrieval, and also poses new challenges in the RO data processing/retrieval and validation. The evaluation of impacts of commercial Small Satellite-based RO data in data assimilation of NWP under NOAA’s Commercial Weather Data for RO (CWD RO) also calls for quick calibration/validation and processing of Small Satellite-based multi-RO mission data. The RO data were not used in an optimal way in the current operational NWP systems due to inadequately resolution of the bending angle variation over small-scale refractivity irregularities. 

This project provides GNSS RO R&D support to NOAA Center for Satellite Applications and Research (STAR), NOAA Office of Projects, Planning and Analysis (OPPA), and NOAA’s Office of Systems Architecture and Advanced Planning (OSSAP). The RO data sources include COSMIC-2 and CWD RO sensors such as GeoOptics and Spire, and other government and partner RO missions selected by NOAA STAR, OPPA and OSAAP. The work covers enterprise L1a to L1b (excess phase) and L1b to L2 (bending angle and refractivity) RO data processing/retrieval algorithm and software development, testing and validation for multi-RO missions. The data products generated from this project will be disseminated to NOAA/STAR for data quality monitoring and further distribution. The work also provide critical support for optimizing the exploitation of multi-mission RO data in NWP and improving impacts of satellite-based RO derived atmospheric profiles for assimilation into operational National Weather Service (NWS) numerical forecasts and models.