500 mb winter variability over the Antarctic (Palmer) Peninsula

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Abstract

Winter time variability of heights over the Antarctic peninsula, Weddell Sea and Queen Maud Land are shown to have important contributions from correlations between the zonally averaged height field ([Z]) and longitudinally asymmetric motions. This is different from what it is observed at other longitudes, where the time variance can be explained in terms of variance of the zonally averaged fields plus the variance of deviations from zonal averages. It is shown that when [Z] is larger than its winter average a pattern with southerlies over the Weddell Sea at 500 mb and northerlies over eastern Antarctica develops south of 60°S. These southerlies are found displaced about 15° northward with episodes of meridional wind magnitudes over eastern Antarctica larger than 2 m/s. The equivalent barotropic structure of Southern Hemisphere tropospheric long waves justify extension of the 500 mb results presented here to higher levels. Recent measurements taken by the Airborne Antarctic Ozone Experiment in the upper troposphere and lower stratosphere (10 to 18 km above sea level) have detected the presence of ozone depleted air over the Antarctic Peninsula and Weddell Sea. It is conjectured here, that this may be partly due to the transport of ozone poor air from high-latitudes into this region.

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