Development and Evaluation of the Rapid Refresh Ensemble Data Assimilation and Forecast System

Continued efforts are being contributed to the development and evaluation of the Rapid Refresh Forecast System (RRFS), as the NOAA regional numerical weather prediction (NWP) modeling evolves into the Finite-Volume Cubed-Sphere (FV3)-based Unified Forecasting System (UFS). The ensemble data assimilation and forecast component of RRFS, the RRFS-RDAS, consists of 30-member ensemble hourly data assimilation cycling, which includes ensemble cloud analysis (mainly cloud clearing), EnKF analysis of the conventional observations and the direct radar reflectivity data assimilation, and a 2-way coupling between the EnKF cycled ensemble members (being re-centered at the control analysis) and a control run (with hybrid GSI analysis using the RRFS ensemble 1-hour forecast). The ensemble free forecast is subset from the EnKF members and runs at select cycles daily with stochastic physics (SPP, SPPT). In addition to the real-time runs, multiple retrospective experiments are conducted to evaluate and tune the RDAS configuration, including both the deterministic and ensemble data assimilation. This presentation will share preliminary evaluation of the regional ensemble data assimilation system and further research and development of the system.