大气科学2011，Vol.35Issue(5)：801-817,17.
与西澳州西南部冬季降水相联系的大气环流特征分析
The Characteristics of Atmospheric Circulation Associated with Austral Winter Rainfall in Southwest Western Australia
摘要
Abstract
Southwest Western Australia (SWWA) locates in the southwest corner of Western Australia. Its capital, Perth, is not only the political, economic, cultural, educational, and tourism center of Western Australia, but also the wine region and wheat belt of Western Australia. The observed rainy season precipitation over SWWA has significantly declined since the 1950s. The reduction in austral winter rainfall resulted in an even sharper fall in the stream flow in southwestern Australia and heavily impacted the water resources in the state. Based on the observation data and reanalysis datasets in recent 6 decades, the variability and circulation features influencing the SWWAaustral winter rainfall (SWR) are investigated The impacts of the known modes, which may have impacts on the Australian rainfall, El Nino-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), ENSO Modoki (EM), and Southern Hemisphere Annular Mode (SAM) on the SWR are analyzed. It is found that they all cannot explain the long term rainfall variation of the SWR in neither early (May to July, MJJ) nor late (August to October, ASO) austral winter. Particularly, the reported significant inverse relationship between the SAM and SWR is caused by an extreme year. Based on the investigation on rainfall distribution over SWWA, seasonal march of the circulation features, dynamical and thermal structures of the atmospheric circulation, and thermal contrast between land and sea over wider southwest Australia, the authors find that the circulation over SWWA shows strong seasonally, and exhibits monsoonal characteristics, that is, alternate wet and dry seasons, seasonal reversal of prevailing winds, and an evident land-sea thermal contrast. Taking account of these monsoonal characteristics, the authors propose the concept of monsoon-like southwest Australian circulation (SWAC), and discuss the relationship between the SWAC and the SWR. The result indicates that the variability of SWAC contributes to the variation of SWR, whose weakening is a possible reason for the SWR decreasing.关键词
西澳州西南部类季风环流/季风/厄尔尼诺—南方涛动/降水/南半球环状模/印度洋偶极子Key words
monsoon-like Australian circulation, monsoon, ENSO, precipitation, Southern Hemisphere Annular Mode, Indian Ocean dipole分类
天文与地球科学引用本文复制引用
李建平,李艳杰,冯娟..与西澳州西南部冬季降水相联系的大气环流特征分析[J].大气科学,2011,35(5):801-817,17.基金项目
国家重点基础研究发展规划项目2010CB950400,国家自然科学基金资助项目41030961 （）
