Analysis and Prediction of the Upper Ocean Using GEOS iODAS

Robin Kovach

Seasonal-to-Interannual coupled forecasts are conducted on an experimental basis in near real time with the GEOS-5 AOGCM. A suite of 30-year 9-month hindcasts is available, initialized with the GEOS-IODAS, MERRA-Land, and MERRA atmospheric fields. Forecasts are initialized every 5 days, with 7 to 10 ensemble members initialized on the date closest to the beginning of the month. The ensemble members are generated by coupled model breeding and by independent perturbations in the ocean and atmosphere.

First, in-situ and satellite observations are assimilated into the GEOS iODAS, a system for both ocean and sea-ice data assimilation. It is integrated within the broader GEOS-5 model and data assimilation system using the Earth System Modeling Framework (ESMF). By using an object-oriented framework, the analysis systems are model-independent, but have been implemented and tuned for the Modular Ocean Model Version 4.1 (MOM4.1) developed by the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) and the CICE model developed by Los Alamos National Laboratory. The ocean analysis fields from the iODAS are then used to initialize the GEOS-5 AOGCM in order to produce the seasonal forecasts.

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