Towards Coupled DA in NASA GEOS System - Developments in the Ocean context
Version 3 (V3) of the Sub-seasonal to Seasonal (S2S) prediction system is scheduled to be operational by Q2FY2019 implementing a "coupled" atmosphere-ocean modeling framework within the Goddard Earth Observing System (GEOS) and its respective data assimilation counterparts. The atmospheric data assimilation relies on the Gridpoint Statistical Interpolation (GSI) implementation of hybrid four-dimensional ensemble-variational (H4DEnVar) for assimilation of observations to provide the best estimate of the atmosphere. The atmospheric general circulation model (AGCM) is a 13km FV3-based dynamical model. The ocean modeling framework is based on Modular Ocean Model version 5 (MOM5) at a 1/4 degree resolution employing a Local Ensemble Transform Kalman Filter (LETKF) to provide the initial conditions for the oceanic state. The focus of this presentation will be the plans and advances made towards the implementation of a newer version of the ocean model, MOM6 and its data assimilation framework. The data assimilation system used for V4 of the S2S system will be based on the Joint Effort for Data assimilation Integration (JEDI) framework; specifically the use of a Unified Forward Operator (UFO) for simulating observations and using the Object Oriented Prediction System (OOPS) for providing the state estimate.
Dr. Rahul Mahajan NASA Goddard Space Flight Center