An approach to improvement temperature and moisture retrievals from the GOES Sounder measurements

The sounder instrument aboard the Geostationary Operational Environmental Satellite series (GOES-8, 9, 10, 11, and 12) currently provides information on the changes in the atmospheric state using a physically-based retrieval of temperature and moisture profiles. The GOES Sounder typically samples the continental U.S. and surrounding oceanic regions on an hourly basis. As a first step in the retrieval process, guess profiles of temperature and moisture are generated, usually from short-term numerical model forecasts. Thereupon, the first guess profiles are adjusted so that forward calculations match the Sounder measured radiances; this process results in the final retrievals. To date, GOES moisture retrievals have provided a noticeable improvement over the first guess, while temperature retrievals have remained very similar to the first guess. The lack of temperature profile improvement in the physical retrieval process might be caused by insufficient use of the GOES Sounder radiance information or the implementation of the radiative transfer calculation in the physical retrieval. This study demonstrates that both guess temperature and moisture profiles can be improved (by up to ~ 0.5 K for temperature and ~5% for Total Precipitable Water) when the GOES Sounder radiance measurements are used in a simple statistical retrieval approach. This improvement is significant for the better utilization of the current GOES Sounder data and important for the preparations for the next generation of the GOES Sounder – Hyperspectral Environmental Suite (HES), scheduled for launch in 2012.