HR: 14:40h
AN: OS13D-05    [Abstracts]
TI: Subantarctic Mode Water and Antarctic Intermediate Water in the South Indian Ocean based on profiling floats 2000-2004
AU: * Wong, A P
EM: Annie.Wong@noaa.gov
AF: Annie P.S. Wong, 7600 Sand Point Way, BLDG.3,, Seattle, WA 98115 United States
AB: Four years of Argo float data between 2000 and 2004 have been used to study the properties of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) in relation to local winter mixed layer properties and frontal regimes in the South Indian Ocean. The accuracy of salinity in the selected Argo data set between $15^{\circ}$S and $40^{\circ}$S has been estimated to be better than 0.01 pss. The basin-wide synoptic view afforded by the float array showed that South Indian Ocean SAMW was more coherent, both in geographical and density space, than previously observed. Its density and thickness distributions are related to the winter mixed layer properties in the local Subantarctic Zone, with progressively denser and thicker SAMW observed to the east. The increase in SAMW thickness east of $70^{\circ}$E may be due to the widening of the Subantarctic Zone after passing the Kerguelen Plateau. South Indian Ocean AAIW was centred on $\sigma_{\theta} = 27.2$ kg m$^{-3}$, with $\theta$-S properties comparable to those of the winter mixed layer in the local Polar Frontal Zone. As observed by previous hydrographic surveys, low-salinity AAIW was injected northward into the subtropical gyre in mid-basin, about $65^{\circ}$E to $80^{\circ}$E. Argo profiles showed that this northward flow extended to the northern extent of the study region at $15^{\circ}$S. The latitude band $30^{\circ}$S to $40^{\circ}$S has the least meridional salinity gradient on density surfaces in AAIW, so it is the best place to detect any consolidated decadal changes in the salinity minimum of South Indian Ocean AAIW.
DE: 4283 Water masses
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting