Submerged jet currents in the Gulf of Mexico

A recent screening study of MMS NTL ADCP 2005 and 2006 data has identified two modes of submerged jet currents in the Gulf of Mexico: (1) submerged speed peaks with inertial period and (2) events isolated in time with no clear periodicity. The latter can be divided further as shallow jet events (between 150m to 600m) and deep jet events (deeper than 600m). The submerged jet events can last a few hours to several days. In order to investigate the jet generation mechanisms and test the predictability of the events, representative events for each mode were studied. Satellite sea surface height (SSH), sea surface temperature (SST) data and forecast data of the Princeton Regional Ocean Forecast System (PROFS) during the selected events have been used. Mode 1 jets are mainly due to downward propagating of inertial oscillations following hurricanes, while the deep jets of mode 2 appear to be caused by deep current propagation along the 1000m isobath. The shallow jets of mode 2 are the result of on-slope flow convergence producing a subsurface downwelling/upwelling cell and frontogenesis over the slope. The comparison of PROFS model and observations shows good predictive skill although the model has the tendency to underestimate current strengths.