Recent Progress on GeoXO Sounder (GXS) Tradeoff Studies

NOAA’s next generation geostationary weather satellite program, the Geostationary Extended Observations (GeoXO), is planning to include the first US hyperspectral infrared (IR) geostationary sounder (GXS). The GXS will provide information of temperature and moisture profiles with high vertical resolution, and it will also offer the realtime observations with high temporal (30 min or less) and high spatial (4 km at nadir) resolutions. This information is much needed to improve long-term, short-term and near-term weather forecasts. NASA selected Ball Aerospace & Technologies Corporation of Boulder (BAE), Colorado, to develop the GXS instrument on September 11 of 2023. The BAE will use a grating spectroscopy system for the GXS. With the release of preliminary spectral response functions from BAE, the Space Science and Engineering Center at University of Wisconsin-Madison in-house GXS fast radiative transfer model, called PFAAST (Pressure layered Fast Atmospheric Transmittance), was developed. In this study, the GXS information content is analyzed with the PFAAST model and the instrument noise from the latest GXS performance and operational requirements Document (PORD) and the BAE Phase A study report provided in December 2022. The results will be compared to previous analyses from the Fourier Transform Spectrometer (FTS) system, as well as the sounders in a low earth orbit (LEO) (e.g., CrIS). In addition to clear sky conditions, the impacts with cloud sky conditions are also investigated. Using a machine learning technique, temperature and moisture sounding capability (and derived parameters) from the GXS are further explored by using simulated radiances, with a focus on the low level profiles and the instability indices.