Spatiotemporal Variability of Near-Inertial Oscillations in the Northeastern Gulf of Mexico

Large near-diurnal oscillations over the DeSoto Canyon region in the northeastern Gulf of Mexico (NeGoM) have been attributed to inertial resonance at the critical latitude for inertial motions with diurnal wind forcing. Over the inner Mississippi Bight Shelf diurnal oscillations have been attributed to tidal forcing. Here, the region between these two studies is investigated through a series of comparative analyses to differentiate between the relative influence of inertial, tidal, and wind forcing which are nearly diurnal. This is performed by comparing HF radar observed surface currents to predicted tidal and inertial motions. The ubiquitous large diurnal oscillations are found to be due to the inertial response to wind forcing (IRWF). The distinction between IRWF and tidal forcing is important because they mix the ocean very differently. The unique view of spatiotemporal variability of the inertial motions provides insight into how they influence mixing in the NeGoM by identifying evidence of propagation, trapping, frequency shifts, and phase shifts.