:::
2014/10/21 14:00 Assistant Prof. C.-W. June Chang（Department of Atmospheric Sciences, Chinese Culture University）
Seminar
Poster： ╱ Post date：2014-10-17NCU IHOS Seminar Announcemnet
Speaker：Assistant Prof. C.-W. June Chang
Place：S-325, Science Building 1
Abstract：
Title：The Madden-Julian Oscillation Changes upon Warming: Time-slice Experiments with the ECHAM5-SIT Coupled Model
Speaker：Assistant Prof. C.-W. June Chang
Department of Atmospheric Sciences, Chinese Culture University
Time：10/21（Tue.）14：00
Place：S-325, Science Building 1
Abstract：
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.
Last modification time：2014-10-17 PM 2:20
