Satellite Radiance Data Impact in RAP Version 4

Version 3 of the Rapid Refresh (RAP) has run operationally at the National Centers for Environmental Prediction (NCEP) since August 2016 and the RAP version 4 was frozen in Spring of 2017 with a planned operationally implementation at NCEP early in 2018. The RAP uses the Gridpoint Statistical Interpolation (GSI) hybrid variational/Ensemble Kalman Filter (EnKF) data assimilation system including an advanced satellite radiance assimilation package developed at NCEP, with ensemble information for the regional assimilation application obtained from the 80-member global ensemble data assimilation system.

A series of radiance upgrades has been tested and included in the RAP version 4, including adding new data (e.g., ATMS, CrIS, IASI, SEVIRI, AIRS etc.) with channel selection, supplementing the standard data feed with direct broadcast data, and delaying partial cycles for improved real-time data coverage. With the new radiance updates, positive impact has been seen from our preliminary retrospective runs. We are conducting a comprehensive data impact study for each individual and/or combined data sets within the framework of RAP version 4 through retrospective runs with short-range forecast verifications. In addition, we will be examining the ABI data from GOES-16 and testing assimilation of them toward a planned inclusion of them in the next version of the RAP and the High-Resolution Rapid Refresh (HRRR) systems. At the conference, we will report on progress to date in all aspects of updates on satellite radiance data assimilation within RAP.