A Numerical Study of Circulation and Associated Variability in the Intra-Americas Sea

A three-dimensional, data-assimilative, regional ocean circulation model is used in simulating circulation, hydrography and associated variability in the Intra-Americas Sea (IAS). The model domain covers the region between 8°N and 32°N and 99°W and 54°W, with a horizontal resolution of 1/6°. The ocean circulation model is driven by 6 hourly wind fields produced by the National Centers for Environmental Prediction and boundary forcing extracted from 5-day reanalysis data produced by the British Atmospheric Data Centre. The model is integrated for 3 years from January 1999 to December 2001. The model performance is assessed by comparing model results with oceanographic observations made in the IAS during this period. Model results are used in the study of the "compensation effect" in which transport variations through the Yucatan Channel are partially compensated by flow through the Old Bahama and Northwest Providence Channels. The compensation effect is found to be associated with baroclinic (2-layer) flow through the Yucatan Channel at timescales longer than 20 days, while at shorter timescales (less than 20 days) the vertical structure of the flow is barotropic.