THE VARIATION OF TRANSPORT THROUGH THE STRAITS OF FLORIDA - A BAROTROPIC MODEL STUDY

A high-resolution, barotropic model of the North Atlantic is used to s tudy the variation of transport through the Straits of Florida on time scales from a few days to seasonal. The model is driven by wind and at mospheric pressure forcing derived from ECMWF twice daily analyses for the years 1985, 1986, 1987, and 1988. The model-computed transports a re compared with the cable-derived estimates of daily mean transport. Atmospheric pressure forcing is found to have an insignificant effect on the model results and can be ignored. A visual comparison between t he model-computed transport and the cable data shows many similarities . Coherence squared between the two time series has peaks between 0.4 and 0.5 and is significant at the 95% confidence level in the period r ange from 6 to 100 days, with a drop in coherence near 10 days. The mo del overestimates the autospectral energy in the period range of 4 to 20 days but underestimates the energy at longer periods. The authors f ind that remote forcing to the north of the straits does not significa ntly affect coherence squared and phase between the model-computed tra nsport and the cable data but is necessary to explain the autospectral energy in the model-computed transports at periods greater than 10 da ys. The most significant failing of the model is its inability to capt ure 8-10 mo timescale events in the cable data. Interestingly, the Wor ld Ocean Circulation Experiment Community Modeling Effort, driven by s ynoptic wind forcing, does exhibit roughly 8-month timescale events, a s seen in the cable data but missed by the barotropic model.