Circulation along the Mexican Caribbean coast

[ 1] Data from an array of seven subsurface upward-looking moored Acoustic Doppler Current Profilers (ADCPs) and four subsurface pressure sensors deployed from August 2002 to August 2003 along the Caribbean coast of Mexico showed that the currents in the area have a predominant northeastward direction along the coast, are coherent within the upper 130 m of the water column, and have a general tendency to increase northward, reaching magnitudes of 2.4 m/s north of Cozumel. In addition, important weeklong reversal periods ( southward flows) are observed around Chinchorro Bank. A vertical current profile EOF analysis at each station indicates high coherence within the study area, with the first vertical mode at each station explaining at least 69% of variance and current vectors aligned with the coast. A second EOF analysis carried out for any uniform depth level using current data from all stations shows high coherence in the horizontal as well. The first mode explains at least 59% of the variance and has a dominant 3-month-long variability. Comparison between the current patterns along the Mexican Caribbean coast and in the Yucatan Channel suggests that dynamics of the entire area might be strongly influenced by the passage of eddies through the region. Comparison of a Singular Spectral Analysis (SSA) of the principal components of currents with the pressure difference across the channels supports the idea of eddies modulating current variability. Numerical model results indicate that high values of the current intensity indexes are associated with eddies. The flow along Chinchorro and Cozumel channels is in geostrophic balance most of the observation time, but with week-long ageostrophic periods which are predominant off Cozumel. These events appear to occur when eddies are traversing the region.