HR: 0800h
AN: OS41B-0529    [Abstracts]
TI: Barotropic zonal jets induced by islands in the southwest Pacific
AU: * Couvelard, X
EM: couvela@noumea.ird.nc
AF: IRD, BPA5, Noumea, 98848, New Caledonia
AU: Marchesiello, P
EM: pmarches@noumea.ird.nc
AF: IRD, BPA5, Noumea, 98848, New Caledonia
AU: Gourdeau, L
EM: gourdeau@noumea.ird.nc
AF: IRD, BPA5, Noumea, 98848, New Caledonia
AU: Lefevre, J
EM: jerome.lefevre@noumea.ird.nc
AF: IRD, BPA5, Noumea, 98848, New Caledonia
AB: The oceanic circulation entering the tropical southwest Pacific (SWP) is dominated by the broad westward flow of the South Equatorial Current (SEC), forced by the trade winds. It has been argued that the numerous islands of the SWP are able to restructure the SEC into a series of deep and narrow zonal jets, which control important pathways connecting equatorial and extra-equatorial signals. The primary objective of this work is to improve our understanding of the structure and dynamics of SWP zonal jets, giving special attention to topographic effects. Our study is based on the use of a high-resolution regional oceanic model, whose solution is compared with observations, as well as with solutions from global models and the Sverdrup relation. Our model indicates that the regional topography drives a general equatorward shift of the SEC, which is beneficial to the North Fiji, North Vanuatu and North Caledonian Jets. A depth-integrated vorticity budget shows that this topographic effect is considerably attenuated by baroclinicity and advection processes, but not to the point of total compensation as often admitted for the interior ocean. The effect of non-linear advection is to allow flow rectification of the jets fluctuations, consistent with the Rhines effect, which takes the form of zonally elongated dipole circulations in the leeward side of the islands.
DE: 4534 Hydrodynamic modeling
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting