The Stratospheric Antarctic Intraseasonal Oscillation during the Austral Winter

• Main Author: Hsu, Huang-Hsiung; Weng, Shu-Ping
• Other Authors: 國立臺灣大學大氣科學系
• Format: Article in Journal/Newspaper
• Language: Chinese
• Published: 臺北市:國立臺灣大學大氣科學系 2001
• Subjects: Antarctic; Austral; Antarc*; Antarctica
• Online Access: http://ntur.lib.ntu.edu.tw/handle/246246/20060927123013132300; http://ntur.lib.ntu.edu.tw/bitstream/246246/20060927123013132300/1/stratospheric30daywave.pdf

This study discovers an eastward-propagating circulation pattern in the stratospheric Southern Hemisphere based on the UKMO UARS assimilated analysis & the TOMS total ozone. The pattern is named as the Stratospheric Antarctic Intraseasonal Oscillation (SAIO) because of its intraseasonal time scale & its repeated appearance in the high latitudes of the Southern Hemisphere. The SAIO has a wave-number-one structure & propagates eastward around the globe in about 30 days, indicating a periodicity of 30 days. The oscillation has an equivalent barotropic vertical structure, which extends from the lower stratosphere to the lower mesosphere. It has close correspondence with the tropospheric fluctuation, which tends to be 180 degree out of phase with its stratospheric counterpart. The SAIO interacts with the mean flow vigorously during its evolution, as revealed by the analysis of the localized E-P flux. The wave-mean flow interaction leads to either the enhancement or the weakening of the zonal asymmetry of the circumpolar jet stream, depending on the phase of the oscillation. It is also found that the wave-mean flow interaction contributes partially to the eastward propagation of the SAIO. Stratosphere-troposphere interaction is clearly indicated by the significant upward wave activity emanating from the upper troposphere into the stratosphere over Antarctica near the dateline. The convergence of this wave activity contributes to the enhancement of the SAIO.