The influence of tropical Indian Ocean warming on the Southern Hemispheric stratospheric polar vortex |
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Authors: | ShuangLin Li |
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Institution: | (1) Nansen-Zhu International Research Centre, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China |
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Abstract: | During the past decades, concurrent with global warming, most of global oceans, particularly the tropical Indian Ocean, have
become warmer. Meanwhile, the Southern Hemispheric stratospheric polar vortex (SPV) exhibits a deepening trend. Although previous
modeling studies reveal that radiative cooling effect of ozone depletion plays a dominant role in causing the deepening of
SPV, the simulated ozone-depletion-induced SPV deepening is stronger than the observed. This suggests that there must be other
factors canceling a fraction of the influence of the ozone depletion. Whether the tropical Indian Ocean warming (IOW) is such
a factor is unclear. This issue is addressed by conducting ensemble atmospheric general circulation model (AGCM) experiments.
And one idealized IOW with the amplitude as the observed is prescribed to force four AGCMs. The results show that the IOW
tends to warm the southern polar stratosphere, and thus weakens SPV in austral spring to summer. Hence, it offsets a fraction
of the effect of the ozone depletion. This implies that global warming will favor ozone recovery, since a warmer southern
polar stratosphere is un-beneficial for the formation of polar stratospheric clouds (PSCs), which is a key factor to ozone
depletion chemical reactions.
Supported by National Natural Science Foundation of China (Grant Nos. 40775053 and 90711004), National Basic Research Program
of China (Grant No. 2009CB421401), and Innovation Key Program of Chinese Academy of Sciences (Grant Nos. KZCXZ-YW-Q11-03,
KZCZ2-YW-Q03-08) |
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Keywords: | tropical Indian Ocean warming Southern Hemispheric stratospheric polar vortex atmospheric general circulation model ensemble experiments planetary wave |
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