报告题目：Recent summer rainfall increase and surface cooling over Northern Australia since the late 1970s: A response to warming in the tropical Western Pacific
报告时间：2017年5月11日 (星期四) 13:30-14:30
报告地点：尚贤楼1楼108报告厅
报告主持人: 曹春正 副教授
报告内容简介：
Rainfall over northern Australia (NA) in austral summer (December to Febueary) is the largest water source of Australia. Previous studies have suggested a strong zonal-dipole trend pattern in austral summer rainfall since 1950, with rainfall increasing in northwest Australia (NWA) but decreasing in northeast Australia (NEA). The dynamics of rainfall increase in NWA was linked to sea surface temperature (SST) in the south Indian Ocean and the rainfall decrease in NEA was associated with SST in the northeast Indian Ocean.
This study reports that, in contrast to a zonal-dipole trend pattern, a dominant wetting pattern over NA has recently been observed in the post-1979 satellite era. The recent NA rainfall increase also manifests as the first leading mode of summer rainfall variability over the Australian continent. Further investigation reveals that SST in the tropical western Pacific (TWP) has replaced the SST in the south and northeast Indian Ocean as the controlling factor responsible for the recent NA rainfall increase. Direct thermal forcing by increasing TWP SST gives rise to an anomalous Gill-type cyclone centered around NA, leading to anomalously high rainfall. As such, the increasing SST in the TWP induces over 50% of the observed rainfall wetting trend over NA. The increased rainfall in turn induces land surface cooling in NA. This mechanism can be confirmed with results obtained from sensitivity experiments of a numerical spectral atmospheric general circulation model. Thus, increasing SST in the TWP has contributed much of the recent summer rainfall increase and consequently the surface cooling over NA.
专家简介：
李云博士，澳大利亚西澳电力商业情报与数据分析高级咨询顾问，高级预报和模型分析研究员。主要负责西澳电力网络的可靠性和供电量的统计建模和预报研究（包括天气极端事件对电力网络的可靠性和供电量的影响），为西澳电力高层决策和规划管理提供内部高级数据分析咨询和建议。2000-2015年任澳大利亚联邦科学与工业研究组织（CSIRO）首席研究员，从事气候统计学的研究，主要研究领域包括天气和气候极端事件的统计建模、统计降尺度模型、气候变化诊断、降水和气温的统计预报等。
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数学与统计学院
2017-05-10
