Stefan Liess教授报告
题目：Typhoons and Extratropical Pressure Systems: Simulations and Projections
时间：2019年6月6日（星期四）下午2:30—4:30
地点：丹桂苑105报告厅
主持/联系：李双林教授
报告摘要：
The present study analyzes the effect of multiple landfalling typhoons on soil moisture over East Asia. A simulation of three typhoons (Frankie, Gloria, and Herb) during the 1996 typhoon season shows that the Weather Research and Forecasting (WRF) model is representing the general characteristics of each typhoon reasonably well, including the landfalls that occurred in close proximity to each other within nine days. A second simulation where the tropical cyclone signal is removed before landfall does not only reveal that soil moisture is increased by up to 30% in coastal regions after landfall, but it also describes the path of increased soil moisture over East Asia up to 2000 km inland.
A note of caution with simulations and projections is added to this presentation, whereby a comparison of decadal sea level pressure (SLP) trends in seven Coupled Model Intercomparison Project 5 (CMIP5) general circulation models (GCM) to their CMIP3 counterparts reveals an unrealistically strong forecast skill in CMIP3 models for trend predictions for 2001–2011 when using the 1979–2000 period to train the forecast. Boreal-winter SLP trend simulations over five high-, mid-, and low-latitude zones over the 1979–2000 initialization period were ranked based on their performance relative to observations. The same method is used to rank the simulations during the 2001–2011 period. In CMIP3, 17 out of 38 ensemble members retain their rank in the 2001–2011 hindcast period and 3 retain the neighboring rank. However, numbers are much lower in CMIP5 decadal predictions over different decadal time periods. Thus, although the 2001–2011 CMIP3 predictions show statistically significant forecast skill, this skill should be treated as a spurious result that is unlikely to be reproduced by newer GCMs.
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环境学院大气科学系
2019年5月30日
