November 17, 2021
The GMAO High‐Resolution Coupled Model and Coupled Assimilation System for Seasonal Prediction
#### Dr. Andrea Molod (Global Modeling and Assimilation Office(GMAO) at NASA Goddard Space Flight Center) #### 2021년 11월 19일 (금) 11:00 #### Zoom
#### Abstract The Global Modeling and Assimilation Office (GMAO) is about to release a new version of the Goddard Earth Observing System (GEOS) Subseasonal to Seasonal prediction (S2S) system, GEOS‐S2S‐3, that represents an improvement in performance and infrastructure over the previous system, GEOS-S2S-2. The system will be described, including some features unique to GEOS-S2S, and the advantages of increases in resolution, upgrades in the model, expansion of data used for assimilation, and the change in ensemble perturbation strategy and ensemble size will be demonstrated. Results are presented from forecasts, climate equilibrium simulations, and data assimilation experiments. GEOS-S2S-3 is being used to produce a long term (1982-present) weakly coupled reanalysis called MERRA-2 Ocean, along with an extensive suite of retrospective seasonal forecasts. The climate or equilibrium state of the atmosphere and ocean shows a reduction in systematic error relative to GEOS‐S2S‐2, attributed in part to an increase in ocean resolution and to the upgrade in the glacier runoff scheme. The GEOS‐S2S‐3 coupled reanalysis also shows improvements attributed to the assimilation of satellite surface salinity. The forecast skill shows improved prediction of the North Atlantic Oscillation, attributed to the increase in forecast ensemble members. With the release of GEOS-S2S-3 and MERRA-2 Ocean, GMAO will continue its tradition of maintaining a state‐of‐the‐art seasonal prediction system for use in evaluating the impact on seasonal and decadal forecasts of assimilating newly available satellite observations, as well as evaluating additional sources of predictability in the Earth system through the expanded coupling of the Earth system model and assimilation components.