Stratospheric Antarctic Intraseasonal Oscillation during the Austral Winter

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概要

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• This study discovered an eastward-propagating circulation pattern in the stratosphere of the Southern Hemisphere based on the Met Office stratospheric assimilated data and the TOMS total ozone. This pattern is named the Stratospheric Antarctic Intraseasonal Oscillation (SAIO) because of its intraseasonal time scale and its repeated appearance in the high latitudes of the Southern Hemisphere. The SAIO exhibits a wave-number-one structure and propagates eastward around the globe in about 30 days, indicating a periodicity of 30 days. It is characterized by a deep vertical structure extending from the upper troposphere to the upper stratosphere with the amplitude increasing rapidly with height below 5 hPa and decreasing slowly with height above. The pattern exhibits a westward-tilting vertical structure with increasing height below 5 hPa and a more barotropic structure above. This westward-tilting feature is most evident in the eastern hemisphere. The close correspondence between the total ozone and circulation implies the impacts of the SAIO on the ozone hole. The SAIO exhibits active wave activity in the longitudinal band outside the jet stream, i.e., from 60°E eastward to 90°W, and tends to grow in the longitudinal band from 60°E to 120°E where energy is converted both barotropically an baroclinically from the mean flow to the SAIO. Outside this region, the SAIO tends to decay and feed energy back to the mean flow mostly through barotropic processes. The SAIO wave activity propagates upward from the upper troposphere to the upper stratosphere downstream of the high-rising topography in Antarctica. The feature is likely to be the manifestation of a topographically forced planetary wave. However, the periodicity cannot explained by the Rossby wave dispersion. Possible mechanisms are discussed.

• 社団法人日本気象学会の論文
• 2002-09-25

著者

• HSU Huang-Hsiung

  Department of Atmospheric Sciences, National Taiwan University

• Hsu Huang-hsiung

  Department Of Atmospheric Sciences National Taiwan University

• WENG Shu-Ping

  Research and Development Division, Central Weather Bureau

• Weng Shu-ping

  Research And Development Division Central Weather Bureau

関連論文

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• Sub-Monthly Circulation Features Associated with Tropical Cyclone Tracks over the East Asian Monsoon Area during July-August Season
• Simulation of the 1998 East Asian Summer Monsoon using the Purdue Regional Model(Regional Climate Modeling for Monsoon System)
• Stratospheric Antarctic Intraseasonal Oscillation during the Austral Winter

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