Toward the Development of a Coupled COAMPS-ROMS Ensemble Kalman Filter and Adjoint with a Focus on the Indian Ocean and the Intraseasonal Oscillation
Lead PI: Dr. Andrew Moore, University of California, Santa Cruz
Start Year: 2015 | Duration: 3 Years
Partners: University of California, Santa Cruz, Rutgers University of New Jersey, Naval Research Laboratory, Monterey & National Center for Atmospheric Research
This project will explore the problem of data assimilation in a coupled ocean-atmosphere model by merging two existing state-of-the-art models, namely the Naval Research Laboratory’s Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS) and the Regional Ocean Modeling System (ROMS). The new coupled system will draw on the extensive capabilities of both ROMS and the atmospheric component of COAMPS, and in the future will capitalize on the existing tangent linear and adjoint versions of these models. The focus of this project will be on coupled data assimilation using an ensemble Kalman filter (EnKF) approach in conjunction with the Data Assimilation Research Testbed (DART) at NCAR. The new coupled COAMPS-ROMS-DART capability will have tremendous utility not only for process studies and data assimilation, but also for sensitivity analysis via the coupled model adjoint. While the COAMPS-ROMS-DART system will be portable and applicable to any region of the world ocean, the focus of this proposal will be simulation of the intra-seasonal oscillation (ISO) in the Indian Ocean so as to capitalize of data collected during several recent field campaigns in the region. Specific objectives of this project include: (1) interfacing ROMS and COAMPS with the DART; (2) a comparison of the performance of the EnKF and 4D-Var approaches to data assimilation in ocean only and atmosphere only experiments; (3) development of a coupled model capability based on the pre-existing COAMPS and ROMS systems using the Earth System Modeling Framework (ESMF); and (4) an investigation of the merit of the EnKF approach for assimilating data into a coupled model, particularly in the highly dynamic tropical Indian Ocean where air-sea interactions play a fundamental role shaping the monsoon circulation.