Hindcasting of Wind-Driven Anomalies Using a Reduced-Gravity Global Ocean Model

Global versions of the Navy Layered Ocean Model are used to hindcast wind-driven oceanic anomalies. These versions are reduced-gravity with lowest layer infinitely deep and at rest, and grid resolutions of 12 deg and 14 deg are used. Winds at the 1000 millibar level from the European Centre for Medium-Range Weather Forecasts ECMWF are used as forcing functions for the models over the 1981 to 1989 time frame. The ability of the models to reproduce wind-forced anomalies on intraseasonal to interannual time scales is studied by comparing the model solutions with various observational data sets. These include satellite altimetry data, drifting buoy data, and island and coastal sea level data. The effects of varying horizontal and vertical resolution are also detailed. The models are able to hindcast many of the wind-driven anomalies the best correlations is found in the tropical regions where the oceanic anomalies. However, the resolution of the global models used here is not adequate for these. In addition the reduced-gravity models lack the barotropic mode and realistic bottom topography, which can play an important role in the flow instabilities. Ocean models, Ocean forecasting, Fronts, Air-sea interaction.