HR: 0800h
AN: OS41A-0157    [Abstracts]
TI: Wind-drive coastal currents in the Gulf of Tehuatepec: HF radar observations and numerical model simulations.
AU: * Velazquez, F A
EM: federico@uabc.mx
AF: UABC, Km 103 Carr. Tijuana - Ensenada, Ensenada, BC 22800, Mexico
AU: Martinez, J A
EM: martine@uabc.mx
AF: UABC, Km 103 Carr. Tijuana - Ensenada, Ensenada, BC 22800, Mexico
AU: Durazo, R
EM: rdurazo@uabc.mx
AF: UABC, Km 103 Carr. Tijuana - Ensenada, Ensenada, BC 22800, Mexico
AU: Flament, P
EM: pflament@hawaii.edu
AF: SOEST, 1000 Pope road, Honolulu, HI 96822, United States
AB: Most of the studies on coastal dynamics in the Gulf of Tehuatepec (GT) have been focused on mixing processes and mesoscale eddies generated due to strong off-shore wind events, know as Nortes or Tehuanos. In order to investigate the spatial and temporal mesoscale variability of surface dynamic in the GT in February 2005, two HF Radar model WERA were deployed along the shore of Oaxaca, Mexico. The spatial coverage of radars reaches up to 120 km off-shore. The radial velocities were processed to obtain total velocity maps every hour in a regular grid of 5.5 km. space resolution. The information of surface velocity and quickscat/NCEP wind obtained during the first sample days show that exist a coastal current toward the west and, during the wind events, is accelerated and steered toward the southwest. In this same period, we find that spatial density of kinetic energy and divergence of velocity field increase during wind events while the vorticity becomes negative. When strong wind events are not present the surface circulation is weakened, mainly for the zonal component of the wind that is mostly positive (westward). These results are in agreement with the upwelling processes observed on the coast and the anticyclonic eddie generation west of the GT during Tehuanos. Images of sea surface temperature and chlorophyll concentration are also used to observe the signature of wind events near the shore. Complementary to field observations, numerical simulation using a 3D primitive equations model (POM) are used to study the wind-driven circulation in the GT. It has been commonly accepted in previous studies that the strong wind events generate mesoscale eddies. We discuss the limited effect of the wind and the interaction of the wind with a coastal current required to generate long life eddies.
DE: 4546 Nearshore processes
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting