HR: 0830h
AN: OS41B-0801    [PDF]
TI: The Ocean Response to a Brief Westerly Wind Event in the Tropical Pacific Ocean
AU: * Kochurov, A
EM: agkochur@bechtel.com
AF: Bechtel Corporation, 5275 Westview Drive, Frederick, MD 21703 United States
AU: Rothstein, L M
EM: lrothstein@gso.uri.edu
AF: Graduate School Of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, RI 02882 United States
AB: The ocean response to atmospheric intraseasonal variability in the tropical Pacific Ocean is investigated using the URI Ocean General Circulation Model. The model performance in simulating the oceanic annual cycle so important for providing the background variability upon which the intraseasonal time scales can be properly studied, is evaluated by examining its sensitivities to 1) details of the air-sea flux parameterization, 2) different sources for the wind forcing products, and 3) the meridional extent of the model domain. The model fields of temperature, salinity and currents in the tropical Pacific agree reasonably well with observations and thus provide adequate initial conditions for the model experiments with anomalous intraseasonal atmospheric forcing. We build up our understanding of how high-frequency forcing of wind affects the ocean's annual variability by increasing the complexity of experiments. We start with a simple experiment in which a resting ocean is forced with a brief (10-day) wind burst and proceed with experiments for a circulating ocean forced with wind anomalies superimposed upon climatological air-sea fluxes. The main effect of the realistic background ocean conditions is that the strongest response to anomalous wind forcing is observed along the equator in the vicinity of the eastern edge of the western Pacific warm pool. The largest ocean anomalies result from the displacement of the strong temperature and salinity gradients in the Eastern Warm Pool Convergence Zone (EWPCZ). It is argued that this zonally non-uniform ocean response is primarily due to significant vertical and longitudinal variations of the salinity field associated with the western Pacific freshwater pool. Eastward advection, by remotely forced Kelvin waves and nonlinear interactions between these waves and a zonally-varying background ocean stratification, is identified as an important mechanism of the EWPCZ displacement.
DE: 4227 Diurnal, seasonal, and annual cycles
DE: 4231 Equatorial oceanography
DE: 4255 Numerical modeling
DE: 4504 Air/sea interactions (0312)
DE: 4528 Fronts and jets
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting