HR: 0800h
AN: A51A-0023    [Abstracts]
TI: Oceanic Response to Atmospheric Forcing Structure in Eastern Pacific Ocean
AU: * Shay, L K
EM: nshay@rsmas.miami.edu
AF: University of Miami/RSMAS, 4600 Rickenbacker Causeway, Miami, FL 33149-1098 United States
AB: During EPIC2001, oceanic current, temperature and salinity profiles were acquired by deploying expendable profilers from research aircraft flights above the warm pool and along the 95oW transect. Analyses of profiler observations support smaller-scale regional variability (i.e. mesoscale) such as wind-stress forced Costa Rica Dome (CRD) that may have extended as far as 110oW based on moored TAO measurements and an observed warm eddy. Along the eastern edge of the CRD, defined by the 20oC isotherm depth, deep flows measured by current profilers were observed to depths of 600 m with currents of 8 to 12 cm s-1. During the six-week experiment, an anticyclonically rotating warm eddy propagated west to southwest at 12-15 cm s-1 based on seven aircraft snapshots in the warm pool and six months of radar altimeter measurements. This phase speed estimate is consistent with Rossby wave dynamics. As this eddy propagated in the warm pool, it had a pronounced impact on the depth of CRD, oceanic mixed layer depth and the atmosphere. Warm eddies in the eastern Tropical Pacific Ocean are fairly common and may either be in response to gap winds (Papagayo) or formed through current instabilities between the North Equatorial Current and the North Equatorial Counter Current. Compared to oceanic climatologies, in situ profiler data exhibits more structure in the upper 100 m where observed buoyancy frequencies (N) are 4 to 6 cph higher across the oceanic mixed layer base. These variations have implications for the oceanic mixed layer budgets and SSTs through shear-induced mixing processes in oceanic and coupled models for weak and strong winds (i.e. Juliette). Regardless of the mixing parameterization implemented in the model, if they relax back to a climatology, the T/S structure will not necessarily support realistic density and buoyancy structure (or eddies) leading to poor predictions of SST and ocean mixed layer responses that feedback to the atmosphere during gap winds and tropical cyclone passage.
DE: 4504 Air/sea interactions (0312, 3339)
DE: 4520 Eddies and mesoscale processes
DE: 4572 Upper ocean and mixed layer processes
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005