Supersquirt: Dynamics of the Gulf of Tehuantepec, Mexico

Abstract

The last two decades have seen a continuing effort to observe and model the response to wind forcing in the coastal ocean along eastern boundaries of ocean basins. The emphasis of research has developed through several stages including: studies of the large-scale steady state, the transient responses in localized areas, the alongshore propagation of wind-induced disturbances, and most recently the evolution of cold filaments extending offshore from the coastal upwelling zone into the open ocean. Frequently associated with such filaments is a strong jet-like current referred to as a "squirt". One interesting area that has been neglected by sea-going oceanographers with modern instrumentation is the Gulf of Tehuantepec. There, large negative temperature anomalies extend several hundred kilometers seaward as a result of offshore, rather than alongshore, winds. By comparison with the size of the typical upwelling-filament temperature and current structure, they might be termed "Supersquirts." Significant chlorophyll anomalies seen in Coastal Zone Color Scanner imagery indicate enhanced primary production in the same region.