Numerical modeling of seasonal and mesoscale hydrography and circulation in the Mexican Central Pacific

Abstract

Based on results from a ROMS numerical model, the dynamics of the Mexican Central Pacific was studied during three years (2003–2005). The model reproduces the mean and seasonal variability of sea surface temperature, as well as mesoscale eddies and meanders from satellite observations. The model adequately represents the main currents in the region: California Current, Mexican Coastal Current, and Gulf of California currents. The Gulf of California currents are linked to the intensificiation of the Mexican Coastal Current and interact in such a way that the lateral shear generates eddies at the entrance to the Gulf of California. The mesoscale eddies were found to have a depth of ~200 m. The eddies generated in the area (internal Rossby radius of deformation, Rd = 40 km) had a diameter L of ~300 km, an orbital speed of 20–30 cm s–1, and a westward translation speed of ~4 cm s–1. Eddies are considered from intermediate to big (L≈ 7.5 Rd, Ro << 1), show geostrophic dynamics, and present a westward drift due to Coriolis variation with latitude (beta effect). The size of the eddies seems to be related to the weakening of the meridional component of wind stress during the North American monsoon.

Two Years of Oceanographic and Meteorological Data from the UNAM Buoy Anchored at Socorro Island in the Mexican Pacific

“…This current pattern is consistent with data reported by Fiedler [24], Molina-Cruz and Martínez-López [25], Glynn et al [26], and Pantoja et al [27]. [30], and in the Ecuador-Peru-Chile Ocean region, the average value was 0.141 µg•L -1 [31].…”

Rapid deepening of tropical cyclones in the northeastern Tropical Pacific: The relationship with oceanic eddies

“…Studies particularly relevant for interactions with tropical cyclones, have identified three other regions located further north than the Gulf of Tehuantepec: (1) the coast of Guerrero (Zamudio et al, 2001); (2) the coasts of Jalisco and Nayarit in the area of Cabo Corrientes and Marías Islands (Zamudio et al, 2007;Pantoja et al, 2012); and (3) the southern part of the Gulf of California (Kurczyn et al, 2012). These studies show the presence of anticyclonic oceanic eddies in those regions also during the hurricane season.…”

“…The maximum values of OHC appear to be dominated almost completely by anticyclonic oceanic eddies generated along the coast of Guerrero, Jalisco and Nayarit in the area of the Marías Islands and Cabo Corrientes, likely triggered by equatorially-originated downwelling coastally-trapped waves that have already traveled more poleward (Zamudio et al, 2007) or by baroclinic instabilities of the near-coastal currents (Pantoja et al, 2012). These values probably also include the presence of eddies in the southern part of the Gulf of California that have been reported by Zamudio as the amount of heat needed to be removed from the ocean per day, for a hurricane to maintain its intensity.…”

Environmental and spatial preferences of dolphinfish (Coryphaena spp.) in the eastern Pacific Ocean off the coast of Mexico

“…The direction and intensity of the California Current has a pattern similar to that of oceanic wind (Pantoja et al, 2012), and both are strongest during winter (Martínez-Rincón et al, 2009;Marín-Enríquez, 2012). Assuming that the 3-month lag hypothesis of Ortega-García and Lluch-Cota (1996) also applies to this oceanic area, because dolphinfish arrive during May-June, ~3-4 months after the winter season, the California Current enters a dormant state, and tropical water masses, with high temperature and low salinity (Torres-Orozco, 1993) move northwards, bringing the preferred SST values to the high ICPUE zone for dolphinfish.…”