The Monterey Bay (MB) ocean forecasting system is based on the Regional Ocean Modeling System (ROMS). The ROMS configuration consists of three-level nested domains covering the U.S. West coast, central California coast, and Monterey Bay at 15-km, 5-km and 1.6-km, respectively.

Both in situ and satellite measurements that are available in real-time are assimilated into ROMS using the 3-dimensional variational (3DVAR) data assimilation scheme. An incremental 3DVAR data assimilation scheme is implemented in ROMS using an assimilation window of six hours. The ROMS nowcast (also known as analysis) is issued every six hours at 03, 09, 15, and 21 GMT hours. The first guess is first obtained from the 6-hour forecast starting from the ROMS nowcast six hours before. During this six-hour data assimilation window, all the available data are assimilated into ROMS-3DVAR system. The data assimilation produces a data correction term that corresponds to the minimal model and data misfit averaged over the entire model domain. The ROMS nowcast is simply the addition of the first guess and data correction.

The MB ROMS real-time forecasting system is executed every night on the JPL computers (dedicated SGI Altix with 12 processors and shared PC cluster computers with 1024 processors). The detailed workflow and the associated timeline are illustrated below.

The MB ROMS ocean forecasting system was developed during the 2003 AOSN (Autonomous Sampling Ocean Network) field program and has been continuously improved in preparing the MB 2006 ASAP (Adaptive Sampling and Prediction) field experiment. The ROMS model was originally developed by the UCLA ROMS group led by Professor Jim McWilliams. This project is jointly funded by NASA and the Office of Naval Research (ONR) through a subcontract with MBARI (Monterey Bay Aquarium Research Institute).