当前位置： 首页»科学研究» 科研动态 【学术讲座】Changes in Southern Hemisphere Storm Tracks and Australian winter rainfall during the Twentieth Century and in Future Projections 发布时间：Wed Apr 14 10:24:00 CST 2010

Title：Changes in Southern Hemisphere Storm Tracks and Australian winter rainfall during the Twentieth Century and in Future Projections

Speaker：Dr Carsten Segerlund Frederiksen

Senior Principal Research Scientist

Australian Bureau of Meteorology

Centre for Australian Weather and Climate Research

Abstract：

Large and continuing reductions in southern Australian winter rainfall are shown to be associated with major shifts in the Southern Hemisphere circulation since the mid-1970s. In particular, these changes have been linked to a reduction in winter storm formation with the growth rate of the leading storm track modes affecting southern Australia being more than 30% lower during the last three decades compared to the period between 1949 and 1968. These effects have become more pronounced with time. In this study, we focus on the changes in southern Australian winter rainfall and relate them to circulation changes that are directly associated with storm formation. We employ two useful diagnostics related to storm development which are (a) the strength of the wintertime subtropical 300hPa zonal wind and (b) the vertical shear in the atmospheric winds, commonly known as baroclinic instability, and is encapsulated in the Phillips (1954) criterion. The relationship between changes in the Phillips criterion and changes in rainfall during the twentieth century is discussed. We also examine the ability of C20C and CMIP3 climate models to simulate the observed changes. Finally, we consider projected changes and trends in rainfall and baroclinic instability in SRES scenarios using results from CMIP3 models.

Time: 2010年4月16日（周五）上午10点

Venue: 北京师范大学化学楼201

欢迎各位师生踊跃参加

 

 

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