Preliminary results from a global ocean/atmosphere prediction system

The Naval Research Laboratory (NRL) is developing a coupled atmosphere-ocean forecast system by integrating several existing, proven atmospheric and oceanic forecasting components into a loosely coupled software system. The atmospheric system consists of the Navy Operational Global Atmospheric Prediction System (NOGAPS), a dynamic atmospheric forecast model initialized by a multivariate optimal interpolation assimilation scheme. The oceanic components of the system consists of the Coupled Ocean Data Assimilation (CODA), an ocean multivariate optimal interpolation program, and the Parallel Ocean Program (POP), a dynamic ocean model that originated at the Los Alamos National Laboratory. In a set of six-month simulations POP is run on a global grid and loosely coupled to NOGAPS, running at resolution, through forecast momentum, heat, and moisture fluxes. NOGAPS is loosely coupled to the ocean by a daily analysis of sea-surface temperature. Ocean data are assimilated through incremental updates of temperature, salinity, velocity and height fields from an analysis run on the same grid as the model, a method widely used in operational atmospheric models. The entire system is designed to run at least once a day and produce 5-10 day forecasts of the ocean and atmosphere for operational use by the Navy. The system is robust and produces a skillful forecast as judged by comparisons with independent data.