Barth, J. A. Oregon State University, barth@oce.orst.edu
Cowles, T. A. Oregon State University, tjc@oce.orst.edu
Richman, J. G. Oregon State University, jrichman@oce.orst.edu
Pierce, S. D. Oregon State University, spierce@oce.orst.edu
Wingard, C. Oregon State University, cwingard@oce.orst.edu

 
MESOSCALE PHYSICAL AND BIO-OPTICAL STRUCTURE OF THE ANTARCTIC POLAR FRONT NEAR 170W
 
As part of the US SOJGOFS program, we obtained multiple, high-resolution vertical sections of physical (temperature, salinity, density, velocity) and bio-optical (fluorescence, multi-wavelength particulate absorption and attenuation) properties of the Antarctic Polar Front (APF) using SeaSoar and shipboard ADCP during cruises in austral Spring and Summer. Each cruise we conducted transects along 170W from 57S to the sea ice edge (62.3S October 1997; 67.7S January 1998) and made grid surveys at the APF. In Spring, the N-S transect revealed sharp temperature and velocity boundaries at the APF with deep mixed layers to the north. Grid surveys of the APF captured a large meander that propagated eastward at 8 cm/s. We found evidence for equatorward subduction of cold water from poleward of the APF. Maps along density surfaces suggest that downwelling occured upstream of the cyclonic portion of the meander and upwelling downstream. Spatially variable high fluorescence was found south of the APF, with 10-15 km wide 'tubes' of high fluorescence aligned along the front. In Summer, the N-S transect revealed a stratified surface layer with a pycnocline between 25 and 60 m across the APF region. Fluorescence was low in the APF region, but strong between 64 and 65.5S.
 
Day: Wednesday, Feb. 3
Time: 02:30 - 02:45pm
Location: Sweeney Center
 
Code: SS31WE0230S