A Convection-Allowing Hybrid Ensemble-Variational Data Assimilation System with a Stand-Alone Version of the FV3

With the unification of the NCEP modelling suite around a common dynamic core, the FV3, work is underway to establish a data assimilation system in support of the future Rapid Refresh Forecast System (RRFS). The RRFS is planned to be a rapidly-updated, convection-allowing ensemble-based data assimilation and forecast system. In support of this effort a convection-allowing hybrid Ensemble-Variational data assimilation system for the StandAlone Regional (SAR) version of the FV3 dynamic core has been developed and is being evaluated. A variety of strategies and schemes have been developed for potential test configurations of this system, some of which include the initialization methods of the data assimilation cycles, generation and use of regional ensembles, and a dual resolution capability. Real data case performance and lessons learned will be presented with a look toward future developments and applications.