GEOS FP - Version 5.22 Details
The GEOS Forward Processing (GEOS FP) system upgrade from GEOS-5.21.2 to GEOS-5.22.0 was completed successfully on March 13, 2019. This upgrade does not result in any changes to the file specification, formats, or access methods for GEOS FP data.
The new release of the GEOS atmospheric data assimilation system includes changes to both the forecast model and the analysis scheme, which are described below.
GCM
The model includes a single scientific update which increases the effectiveness of the ‘sponge’ in the top nine model layers, used to control the vertical propagation of gravity waves. This change produces no discernible qualitative change in the analysis or forecast fields. There are several zero-difference structural changes including an updated capability for re-gridding to and from the Cubed-Sphere and Lat-Lon grids, and support for new grid naming conventions for HISTORY and re-gridding.
Analysis
The analysis was updated to include assimilation of radiances from CrIS and ATMS on the NOAA-20 polar orbiting satellite. The ATMS observations follow the same configuration as those on Suomi-NPP, but the CrIS observations are from the full spectral resolution (FSR) stream. Only longwave channels consistent with Suomi-NPP are implemented; water vapor channels are not utilized. Total column ozone measurements from the OMPS nadir mapper instrument on Suomi NPP have also been added, while NEXRAD velocity-azimuth display (VAD) winds have been disabled in the system. Observation errors for all polar atmospheric motion vectors from MODIS and AVHRR have been re-tuned. Finally, the analysis scheme was updated to allow for inter-channel correlations in the specification of the observation error matrix for AIRS and IASI hyper-spectral infra-red radiances. Overall, these changes result in more accurate short-range forecasts (reduced bias) of tropical middle-tropospheric temperature with respect to radiosonde observations, a similar improved fit to observed winds at high latitudes, and improved medium-range forecasts of middle-tropospheric wind and temperature in the Souther Hemisphere extratropics. There also appears to be an increased bias in tropical upper-tropospheric temperature in some locations, but this is not considered a serious deficiency at the present time.
