Climatological intraseasonal oscillation in the middle–upper troposphere and its effect on the northward migration of the East Asian westerly jet and rain belt over eastern China

2021 ◽  
Author(s):  
Jianying Li ◽  
Boqi Liu ◽  
Jiangyu Mao
Keyword(s):  
East Asian ◽  
Eastern China ◽  
Intraseasonal Oscillation ◽  
Rain Belt ◽  
Upper Troposphere ◽  
Westerly Jet ◽  
East Asian Westerly Jet

scholarly journals Effects of Suppressed Transient Eddies by the Tibetan Plateau on the East Asian Summer Monsoon

2021 ◽  
pp. 1-59
Author(s):  
QIAOLING REN ◽  
XINGWEN JIANG ◽  
YANG ZHANG ◽  
ZHENNING LI ◽  
SONG YANG
Keyword(s):  
Tibetan Plateau ◽  
East Asia ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Jet Stream ◽  
The Tibetan Plateau ◽  
Rain Belt ◽  
Westerly Jet ◽  
Asian Summer ◽  
East Asian Westerly Jet

AbstractIt is known that the Tibetan Plateau (TP) can weaken the transient eddies (TEs) transported along the westerly jet stream. This study investigates the effects of the persistently suppressed TEs by the TP on the East Asian summer monsoon and the associated mechanisms using the NCAR Community Earth System Model. A nudging method is used to modify the suppression of the TEs without changing the steady dynamic and thermodynamic effects of the TP.The suppressed TEs by the TP weaken the East Asian westerly jet stream through the weakened poleward TE vorticity flux. On the one hand, the weakened jet stream leads to less (more) rainfall in northern (southern) East Asia by inducing anomalous moisture convergence, mid-tropospheric warm advection, and upper-level divergence, particularly in early summer when the eastward propagation of TE suppression by the TP is strong. On the other hand, the precipitation anomalies can shift the East Asian westerly jet stream southward and promote the moisture convergence in southern East Asia through latent heat release. Therefore, the persistent suppression of the TEs leads to a southward shift of the East Asian rain belt by a convective feedback, as previously found that the steady thermodynamic and dynamic forcings of the TP favored a northward shift of the rain belt. This study suggests that the anomalously weak TEs can lead to the south-more-north-less rainfall change over East Asia.

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