11.5 The influence of ENSO influence on monthly mean column ozone, geopotential heights and temperature in the Southern Hemisphere winter and spring

Thursday, 11 June 2009: 3:10 PM
Pinnacle A (Stoweflake Resort and Confernce Center)
Marek J. Rogal, AOS Univ. of Wisconsin, Madison, WI; and M. Hitchman

The distribution of ozone is controlled by the combined effects of dynamical and photochemical processes. It has been observed that transient wave activity in the upper troposphere / lower stratosphere (UTLS) strongly modulates total column ozone through horizontal and vertical advection. The high correlation between column ozone and the tropopause pressure in middle latitudes on synoptic time scales has been noted in previous studies. Long-term observations of column ozone in the Southern Hemisphere (SH) show the anthropogenic ozone minimum or Ozone Hole, situated over Antarctica and surrounded by a zonally asymmetric total ozone maximum in latitudes 40-60°S. ENSO variability and its seasonal dependencies are explored in this study. We investigate the hypothesis that ENSO exerts a profound influence on the general circulation of the Southern Hemisphere and through it, on distribution of ozone. Amplitude of column ozone tends to be lower in August through September period during warm phase as well as the maximum tends to be shifted eastward in during winter and early spring. We employ statistical analysis to characterize the role of ENSO modulation in causing differences in the geographical distribution and amplitude of monthly mean column ozone in the winter and spring periods in the SH. To augment the observational part of the study, we apply University of Wisconsin's nonhydrostatic mesoscale model (UW-NMS) to the SH. This modeling study gives a insight into difference in synoptic features during the warm and cold periods of ENSO oscillation.
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