Modeling the effects of southeast asian monsoon outflow on the austral winter circulation

Using observations, analyses and a model, the hypothesis regarding a major teleconnection between the Northern and Southern Hemispheres is researched. This hypothesis involves the possibility that outflow from the Tibetan High (TH) may greatly influence the distribution of ozone in the Southern Hemisphere. During the May through November period southwestward outflow from the Tibetan High near the tropopause across the Indian Ocean modulates the Southern Hemisphere (SH) wave pattern. Coupled with certain modes of planetary wave structure in the Southern Hemisphere, this example of interaction between the NH and SH may lead to the climatological “croissant” pattern of total ozone. We employ the University of Wisconsin Nonhydrostatic Modeling System (UWNMS) together with global meteorological and satellite data, to investigate the possibility that the coupling between the NH Tibetan High and the SH wave pattern exerts a significant influence on ozone distribution in the Southern Hemisphere. Case studies during August 1998 and 2000 are chosen for comparison with UWNMS model runs performed with the use of assimilated 3D ozone data, where the domain spans most of the SH. Model trajectories and fields of various variables allow diagnosis of dynamical processes resulting from the interhemispheric coupling. In particular, the relationship among the quasi-stationary Australian High, traveling synoptic wave packets and stratospheric planetary waves is explored. Furthermore, we model influence of synoptic waves on ozone transport in the dynamically important layer 8-20 km and perform a 3D ozone budget to validate model results. A detailed climatology of the TH-SH coupling using spectral analysis and other diagnostic tools is presented to obtain insight into dynamical mechanisms involved in the redistribution of ozone in the SH as well as modulation of the hemispheric wave pattern.