Performance Assessment and Verification of FORMOSAT-7/COSMIC-2 GNSS Neutral Atmospheric Radio Occultation Data

The launch of the FORMOSAT-7/COSMIC-2 (F7/C2) GNSS radio occultation (RO) mission in June 2019 has advanced RO remote sensing technology and promises to improve weather and space weather prediction and our understanding of their underlying atmospheric processes. The satellites and science payloads were jointly developed by the US National Oceanic and Atmospheric Administration (NOAA), US Air Force, and Taiwan’s National Space Organization (NSPO). F7/C2 follows the highly successful FORMOSAT-3/COSMIC mission that was launched in 2006 and produced approximately 7 million atmospheric soundings improving global weather forecasts and supporting hundreds of weather, climate and space weather scientific studies (Anthes, 2011). F7/C2 consists of six small satellites with GNSS RO payloads that will eventually deploy into operational low Earth orbits (LEO) of 520 km altitude and 24 degree inclination equally spaced in local time. The GNSS RO payloads, called the Tri GNSS Radio occultation System (TGRS), were developed at NASA/JPL and make use of a high-gain beam-forming antenna and advanced RO receiver to track the highly fluctuating GNSS RO signals through the ionosphere and from the stratosphere down to the Earth’s surface. Each TGRS payload is expected to produce almost 1,000 high-quality atmospheric soundings per day from both GPS and GLONASS signals. The NOAA COSMIC-2 Program has developed a Calibration and Validation (Cal/Val) campaign plan to evaluate the quantity and quality of the profile da­ta. This presentation will provide a performance assessment of the current COSMIC-2 neutral atmospheric RO data for each satellite, rising and setting geometries, GPS and GLONASS, and L2P and L2C tracking. Level-1 threshold requirements for profile count, and bending angle, refractivity, and temperature uncertainties for different altitude ranges, will be verified through various instrument-level diagnostics and comparison of COSMIC-2 profiles to other closely located RO profiles (measured by different COSMIC-2 satellites and other RO missions), to nearby radiosondes, and to numerical weather models. A level-1 objective requirement for tropospheric duct height detection will also be evaluated.