Open AccessInfluence of tropical convection on the Southern Hemisphere ozone maximum during the winter to spring transition
Author(s) -
Hitchman M. H.,
Rogal M. J.
Publication year - 2010
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2009jd012883
Subject(s) - extratropical cyclone , anticyclone , stratosphere , climatology , tropopause , southern hemisphere , troposphere , geology , rossby wave , jet stream , atmospheric sciences , atmospheric convection , convection , quasi biennial oscillation , hadley cell , environmental science , jet (fluid) , oceanography , climate change , geography , physics , meteorology , general circulation model , thermodynamics
During the Southern Hemisphere (SH) winter a zonally asymmetric maximum in column ozone develops south of Australia, which amplifies from August through October. This ozone maximum lies in the band 50–60°S and extends from the southern Indian Ocean to the eastern Pacific. It is proposed that the location of the ozone maximum is due to the geographical distribution of outflow from tropical convection in the upper troposphere and lower stratosphere (UTLS), which is concentrated over the southern Indian Ocean. This southward flow of tropical air creates subtropical anticyclones in the UTLS and provides the angular momentum for the entrance to the Australian westerly jet. The ozone‐rich troughs in synoptic waves breaking on the jet contribute to the monthly mean ozone maximum poleward of the jet. As Indonesian convection contracts zonally and shifts eastward during SH spring, so do the Australian jet and ozone maximum. In addition, extratropical planetary waves become more active from August through October. Convective outflow surges lead to amplification of subtropical anticyclones, which often extend into the lower stratosphere and merge with stalling planetary wave ridges. Amplification of these ozone‐rich ridges over the high‐latitude South Pacific contributes to the eastward shift of the ozone maximum. The UTLS over the southern Indian Ocean appears to be a sensitive region where tropical convection can influence extratropical planetary waves via excitation of subtropical anticyclones and propagation of Rossby wave activity through the connecting westerly waveguide.