Towards a high-resolution global coupled navy prediction system

Abstract

A computational project is underway to bring about the realization of a high-resolution global coupled atmosphere/ocean/ice prediction system for Navy meteorological and oceanographic forecasting. A fully coupled near-global ocean/atmosphere prediction system has been constructed using resolutions of 0.75° in the atmosphere and 0.5° in the ocean (eddy-permitting) at the Naval Research Laboratory at Monterey (NRL-MRY). The system consists of the Navy Operational Global Atmospheric System (NOGAPS) that incorporates the NRL Atmospheric Variational Data Assimilation Scheme (NAVDAS), the Los Alamos National Laboratory Parallel Ocean Program (POP), and the Navy Coupled Ocean Data Assimilation (NCODA), an optimal interpolation scheme (see Figure l). The next steps in the development of this system are the inclusion of ice, improving the data assimilation scheme, and moving to higher resolution; fulfillment of these goals is being advanced by university and national laboratory partners. An eddy-permitting fully global coupled ocean/ice simulation is underway using POP and the Los Alamos sea ice model known as CICE. Ensemble runs are being conducted using eddy­ permitting global POP and the Simple Ocean Data Assimilation Scheme (SODA). SODA (Carton et al., 2000), also an optimal interpolation scheme, uses advanced error statistics that are flow dependent, anisotropic, and latitude-depth dependent. Finally, a short (two-year) high-resolution (0.1°, 40-level) global POP simulation forced with daily NOGAPS fluxes is complete following a 2-decade spin-up of this model using National Center for Environmental Prediction (NCEP) atmospheric fluxes. POP, the ocean model common to all these efforts, is a multi-level, primitive equation general circulation model with a free surface boundary condition. POP has been used widely on massively parallel architectures since 1992 when (Smith et al., 1992) reconfigured the Bryan­ Cox-Semtner ("GFDL") ocean model: to run on a Connection Machine 5 (CMS). Since then it has been ported to other platforms (SGI Origin 2000, SGI Origin 3000, Cray T3E, and IBM SP, Cray X I , Earth Simulator, among others) and LANL scientists continue to improve its efficiency. Improvements to physics packages by the modeling community at large are progressively incorporated into POP.