Configuration Testing of GSI within an Operational Environment

The Gridpoint Statistical Interpolation (GSI) 3D-Var system is part of NOAA/NCEPs operational North American Mesoscale (NAM) model, as well as the WRF Rapid Refresh (RR) system. The Air Force Weather Agency (AFWA) is in the processes of implementing the GSI into operations. Extensive testing and evaluation is being conducted by the Developmental Testbed Center (DTC) on the GSI system as applicable to AFWA in order to determine the best operational configuration. The DTC currently maintains a community GSI code that incorporates the latest developments from the research community and is regularly synced with the NCEP/EMC GSI trunk, aiding in the research to operations (R2O) process. The most recent GSI community code release (v3.1), coupled with the latest WRF ARW (v3.4), is being configured and evaluated to provide the best operational configuration.

The testing and evaluation efforts include establishing a functionally similar testing environment in order to determine the best namelist options, QC procedures, and cycling techniques while running applications of interest to AFWA. Additionally, observation impacts and analysis sensitivity will be assessed. This will include discussion of the inherent issues when running limited-area models over data poor regions and when using observations processed outside the GDAS system. Also, ARW specific regional background error (BE) generation is being performed. The impact of the generated and tuned BE will be shown. Finally, verification of deterministic ARW forecasts against the ERA-interim analysis will be examined to determine the impact of the various data assimilation configurations.