NCEP's Next Generation Coupled Forecast System for Subseasonal to Seasonal Scales

NCEP’s mission for S2S prediction requires developing a successor model to the present operational CFSv2. NCEP has recently chosen FV3 as the dynamic core for all the atmospheric models that are run to provide guidance for forecasters. For several years, a concerted effort has taken place, both internal and external to EMC/NCEP, to create the infrastructure of a multi-component global coupled system in the NEMS framework. A benchmark coupled system using the atmospheric spectral GSM (with NOAH land model being internal to GSM) coupled with the MOM5.1 ocean model and the CICE seaice model has been used to develop a verification module which consists of making 144 35-day forecasts from the 1 st and the 15 th of each month, over a 6-year period from April 2011 to March 2017. Skill scores from this small subset have been compared with the operational CFSv2 to test the viability of the system. Preliminary results show that this benchmark system, without any type of tuning, is equal or better than the control operational CFSv2 over the last 6 years. A new configuration consisting of the FV3 dycore, the MOM6 ocean model, WW3 wave model and the CICE sea ice model is being developed using the NEMS coupling strategy. A weakly coupled DA for all of the component system models is also being developed at the same time to provide the most accurate initial conditions for this system. The verification module will be used to test this system with multiple physics packages using the common community physics package driver to develop next generation coupled forecast system for sub seasonal to seasonal scales