Ocean Circulation in the Western Gulf of Mexico Using Self-Organizing Maps

The ocean circulation in the western Gulf of Mexico is influenced by Loop Current eddies (LCEs), which affect the thermohaline structure and distribution of environmental variables as well as the design and management of offshore structures and maritime activities. In this study, we assess the ocean circulation and its variability by applying dual self-organizing maps (SOMs) to a 20-year data set (1993-2012) of salinity and currents at a depth of 200 m from a Hybrid Coordinate Ocean Model. The geospatial variability is characterized via a 7 x 7 SOM, which is further grouped into seven patterns, while the temporal variability is characterized as six distinct regions using a 2 x 3 SOM. The influence of LCEs on the upper slope occurs along the 200-m isobath, a zone under constant pressure by strong currents from impacting eddies. The temporal pattern variability also reveals a clear zone of LCE impact on the continental slope (between latitudes 22 degrees N and 25 degrees N) and a dominant offshore transport pattern around latitudes 25 degrees N to 26 degrees N. A rectified wavelet power spectral analysis reveals a frequency of LCE impact oscillating around four to five months with an estimated ring lifespan of 1 year.