7.7
Atmospheric thermodynamics responsible for the Antarctic circumpolar wave along the sea ice edge around Antarctica
Warren B. White, SIO/Univ. Of California, La Jolla, CA; and P. Gloersen and I. Simmonds
We find the Antarctic Circumpolar Wave (ACW) propagating slowly eastward along the sea ice edge around Antarctic during autumn-winter (AMJJAS) for 10 years from 1983 to 1992, with retracted sea ice extent (SIE) anomalies coinciding with warm sea surface temperature (SST) anomalies and poleward meridional surface wind (MSW) anomalies, with high sea level pressure (SLP) anomalies displaced 90° of phase to the east and coinciding with decreased cyclone density (CD) and cyclone intensity (CI) activity. We diagnose troposphere temperature and vorticity budgets utilizing National Centers for Climate Prediction (NCEP) reanalysis data, finding the warm SST anomalies in the ACW associated with upward sensible-plus-latent heat flux (QS+QE) and positive precipitation (PCP) anomalies, both associated with anomalous mid-level diabatic heating. The latter is balanced in the temperature budget principally by anomalous vertical heat advection, giving rise to anomalous ascent throughout the column, accompanied by anomalous upper-level divergence and low-level convergence. The latter is balanced in the vorticity budget principally by the anomalous poleward advection of planetary vorticity, yielding poleward MSW anomalies, as observed. Yet, the low-level poleward wind anomalies also advect warmer air poleward, which is balanced in the temperature budget by the mean zonal advection of anomalous cool air and diabatic cooling anomalies, the latter associated with downward QS+QE anomalies directed into the ocean. Since the latter is displaced to the east of upward SST-induced QS+QE anomalies, it yields an anomalous SST warming tendency eastward of warm SST anomalies, contributing to the eastward phase propagation of the ACW along the sea ice edge.
Session 7, The Southern Hemisphere oceans and the cryosphere
Tuesday, 25 March 2003, 1:30 PM-5:15 PM
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