Intermodel Diversity in the Zonal Location of the Climatological East Asian Westerly Jet Core in Summer and Association with Rainfall over East Asia in CMIP5 Models

2019 ◽  
Vol 36 (6) ◽  
pp. 614-622 ◽  
Author(s):  
Zhongda Lin ◽  
Yuanhai Fu ◽  
Riyu Lu
Keyword(s):  
East Asia ◽  
East Asian ◽  
Cmip5 Models ◽  
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.

An evaluation of East Asian Extratropical cyclones in CMIP5 models and their response to greenhouse warming

2020 ◽  
Author(s):  
Jaeyeon Lee ◽  
Jaeyoung Hwang ◽  
Seok-Woo Son ◽  
John Gyakum
Keyword(s):  
East Asia ◽  
East Asian ◽  
Vertical Wind Shear ◽  
Coupled Model ◽  
Static Stability ◽  
Relative Vorticity ◽  
Cmip5 Models ◽  
Leeward Side ◽  
Extratropical Cyclones ◽  
The Tibetan Plateau

<p>The extratropical cyclones (ETCs) over East Asia and their possible future changes are evaluated using the Coupled Model Intercomparison Project phase 5 (CMIP5) models. The East Asian ETCs are identified using an automated tracking algorithm applied to the 850-hPa relative vorticity field for both reference data (ERA-Interim reanalysis data) and model data. The CMIP5 models well capture the spatial distribution of East Asian ETC properties, although significant biases are present around the high-topography regions. Based on the individual model biases, Best 5 models are selected and used for examining the future changes of East Asian ETCs. In future climate, Best 5 shows declined cyclogenesis in the leeward side of the Tibetan Plateau, which is partly responsible for the decreased ETC frequency over the western North Pacific. The intensity of individual ETCs is also projected to decrease in a warm climate. These changes could be attributed to the combined effect of increased static stability and decreased vertical wind shear in East Asia, which means reduced local baroclinicity. It is also found that CMIP6 models have smaller bias than Best 5 CMIP5 models, indicating that the result documented in this study may change in quantity when newly-available CMIP6 models are utilized.</p>

scholarly journals Distinct effects of winter monsoon and westerly circulation on dust aerosol transport over East Asia

2021 ◽  
Author(s):  
Liu Yang ◽  
Zhengguo Shi ◽  
Hui Sun ◽  
Xiaoning Xie ◽  
Xiaodong Liu ◽  
...  
Keyword(s):  
East Asia ◽  
Lower Layer ◽  
East Asian ◽  
Asian Dust ◽  
Winter Monsoon ◽  
Dust Aerosol ◽  
Tibet Plateau ◽  
Particle Sizes ◽  
Westerly Jet ◽  
Westerly Winds

Abstract The transport of dust aerosol in East Asia is affected by the East Asian winter monsoon (EAWM) and westerly circulation both for modern and geological periods. There are obvious seasonal changes in the intensity and range of EAWM and westerly jet; however, their impacts and relative contributions to East Asian dust transmission are still unclear. In this study, we use Regional Climate Model 4 (RegCM4) to simulate the changes in the East Asian dust cycle under present conditions, assessing the effects of EAWM and westerly jet on dust transport. The results show that the dust at the upper level is mainly transported by the westerly circulation, while that of the lower layer is mainly transported by the EAWM. In March, the westerly jet is located on the south side of the Tibet Plateau and the high-level dust aerosol is transmitted eastward to the northern Pacific. Low-level dust is transmitted to the southeastern China with the influence of EAWM. With the northward shift of the westerly jet, the control range of the westerly winds increases in May and their correlations are weakened. In contrary, the impact of EAWM on the lower layer dust is enhanced. Due to the strengthened interaction between the westerly winds and the EAWM, they can both affect the middle-level dust transmission. The effect of EAWM is sensitive to the dust particle sizes. Under the action of EAWM, fine-grained dust is transmitted far away, while coarse-grained dust is limited to the vicinity of the source area. Once the dust is carried to the westerly layer, the influence of westerly winds on the transmission of different particle sizes dust is similar.

scholarly journals Potential Influence of Arctic Sea Ice to the Interannual Variations of East Asian Spring Precipitation*

2016 ◽  
Vol 29 (8) ◽  
pp. 2797-2813 ◽  
Author(s):  
Zhiwei Wu ◽  
Xinxin Li ◽  
Yanjie Li ◽  
Yun Li
Keyword(s):  
Sea Ice ◽  
East Asia ◽  
Wave Train ◽  
East Asian ◽  
Arctic Sea Ice ◽  
Interannual Variations ◽  
Spring Precipitation ◽  
Westerly Jet ◽  
Arctic Sea ◽  
Subtropical Westerly Jet

Abstract Arctic sea ice (ASI) and its potential climatic impacts have received increasing attention during the past decades, yet the relevant mechanisms are far from being understood, particularly how anomalous ASI affects climate in midlatitudes. The spring precipitation takes up as much as 30% of the annual total and significantly influences agriculture in East Asia. Here, observed evidence and numerical experiment results show that the ASI variability in the Norwegian Sea and the Barents Sea in the preceding winter is intimately connected with interannual variations of the East Asian spring precipitation (EAP). The former can explain about 14% of the total variance of the latter. The ASI anomalies persist from winter through the ensuing spring and excite downstream teleconnections of a distinct Rossby wave train prevailing over the Eurasian continent. For the reduced ASI, such a wave train pattern is usually associated with an anomalous low pressure center over the Mongolian plateau, which accelerates the East Asian subtropical westerly jet. The intensified subtropical westerly jet, concurrent with lower-level convergence and upper-level divergence, enhances the local convection and consequently favors rich spring precipitation over East Asia. For the excessive ASI, the situation tends to be opposite. Given that seasonal prediction of the EAP remains a challenging issue, the winter ASI variability may provide another potential predictability source besides El Niño–Southern Oscillation.

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