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103/10/21 14:00 中國文化大學大氣科學系張瓊文助理教授 演講
演講公告
張貼人：網站管理員 ╱ 公告日期：2014-10-17演 講 公 告
主講人：張瓊文 助理教授
地點：中央大學科學一館S-325教室
摘要：
講題：The Madden-Julian Oscillation Changes upon Warming: Time-slice Experiments with the ECHAM5-SIT Coupled Model
主講人：張瓊文 助理教授
中國文化大學大氣科學系
時間：10月21日（星期二）下午2點
地點：中央大學科學一館S-325教室
摘要：
The Madden-Julian Oscillation (MJO; Madden and Julian 1971, 1972) is one of the most complex and influential aspects of tropical meteorology. While CMIP3 and CMIP5 project a more stabilized atmosphere in the future, the understanding of the future behavior of MJO – the 30-60 day oscillation manifested with rainfall, cloudiness, and zonal wind disturbances – is of vital importance and timely. The study uses a newly developed coupled climate model, ECHAM5-SIT, which shows a marked improvement in the simulation of the MJO, when ocean-atmosphere interaction involving the upper few meters of the ocean is accurately represented. Two time-slice experiments are conducted for understanding the MJO spatial and temporal behavior changes relative to the 20th century climate condition for the extremely warming 21th century RCP8.5 condition. We identify that the MJO characteristics under global warming include faster frequency and eastward propagation, intensified deep convection and enhanced westward tilting of the wind divergence despite of the slightly weakened winds. The moisture flux analysis shows that, relative to the current climate, both the boundary layer moistening and the mid-level moisture source for the deep convection are enhanced. The former moistening enhancement is mainly subject to the wind divergence enhancement, while the later have additional contribution from the background moisture increase associated to the global warming. It is to say that under the warming climate, the MJO becomes more efficient in building up the moisture for the boundary layer moistening and the deep convection. The enhanced boundary layer moistening supports the frictional moisture convergence mechanism of a faster eastward moving MJO.
最後修改時間：2014-10-17 PM 2:20
