Potential factors modulating ENSO's influences on the East Asian trough in boreal winter

2020 ◽  
Vol 40 (12) ◽  
pp. 5066-5083 ◽  
Author(s):  
Shui Yu ◽  
Jianqi Sun
Keyword(s):  
East Asian ◽  
Boreal Winter ◽  
East Asian Trough ◽  
Potential Factors

scholarly journals Intraseasonal Variation of the Strength of the East Asian Trough and Its Climatic Impacts in Boreal Winter

2016 ◽  
Vol 29 (7) ◽  
pp. 2557-2577 ◽  
Author(s):  
Lei Song ◽  
Lin Wang ◽  
Wen Chen ◽  
Yang Zhang
Keyword(s):  
East Asia ◽  
East Asian ◽  
Quantitative Description ◽  
Storm Track ◽  
Northern Eurasia ◽  
Boreal Winter ◽  
Near Surface ◽  
East Asian Trough ◽  
Climatic Impacts

Abstract The East Asian trough (EAT) is a distinct component of the boreal winter circulation whose strength corresponds to the amplitude of the Northern Hemispheric stationary waves. In this study, the mechanism and climatic impacts of the intraseasonal variations of the EAT’s strength are investigated through composite analysis and dynamical diagnostics. The significant roles played by the low-frequency Rossby wave (RW) and synoptic transient eddy (TE) are revealed. Before the peaks of strong EAT events, an upper-tropospheric RW train propagates across northern Eurasia and interacts with preexisting surface cold anomalies over central Siberia. This pattern intensifies the Siberian high and causes RW convergence toward the EAT, leading to 30% of the EAT’s amplification directly via the RW-induced feedback forcing. Meanwhile, RW weakens the background baroclinicity and reduces TE activities near the entrance region of the North Pacific storm track. The TE-induced feedback forcing leads to another 30% of the EAT’s amplification. The evolution and dynamical processes of the weak EAT events generally resemble those of the strong events with opposite signs. These results are consistent with the knowledge on the mechanism of the strong and weak EAT events regarding the role of RWs with additional quantitative description and provide new insights regarding the role of TEs. Variations of the EAT’s strength exert significant climatic impacts on East Asia and its downstream region. Near-surface air temperature is below (above) normal over East Asia during the growth and peak stages of the strong (weak) EAT events and above (below) normal over North America afterward.

Vertical tilt structure of East Asian trough and its interannual variation mechanism in boreal winter

2013 ◽  
Vol 115 (3-4) ◽  
pp. 667-683 ◽  
Author(s):  
Shangfeng Chen ◽  
Xiaolong Chen ◽  
Ke Wei ◽  
Wen Chen ◽  
Tianjun Zhou
Keyword(s):  
Interannual Variation ◽  
East Asian ◽  
Boreal Winter ◽  
East Asian Trough ◽  
Variation Mechanism

scholarly journals Recent Winter Precipitation Changes over Eastern China in Different Warming Periods and the Associated East Asian Jets and Oceanic Conditions

2017 ◽  
Vol 30 (12) ◽  
pp. 4443-4462 ◽  
Author(s):  
Danqing Huang ◽  
Aiguo Dai ◽  
Jian Zhu ◽  
Yaocun Zhang ◽  
Xueyuan Kuang
Keyword(s):  
East Asia ◽  
Southern China ◽  
East Asian ◽  
Eastern China ◽  
Winter Precipitation ◽  
Northeastern China ◽  
Boreal Winter ◽  
The South ◽  
East Asian Trough ◽  
Siberian High

Global-mean surface temperature has experienced fast warming during 1985–98 but stabilized during 1999–2013, especially in boreal winter. Climate changes over East Asia between the two warming periods and the associated mechanisms have not been fully understood. Analyses of observation and reanalysis data show that winter precipitation has decreased (increased) over southern (northeastern) China from 1985–98 to 1999–2013. Winds at 300 hPa over East Asia strengthened during 1999–2013 around 30°–47.5°N but weakened to the north and south of it. This change pattern caused the East Asian polar front jet (EAPJ) and the East Asian subtropical jet (EASJ) to shift, respectively, equatorward and poleward during 1999–2013. Associated with these jet displacements, the Siberian high enhanced and the East Asian trough shifted westward. The enhanced Siberian high strengthened the East Asian winter monsoon and weakened southwesterly winds over the South China Sea, leading to precipitation decreases over southern China. The westward shift of the East Asian trough enhanced convergence and precipitation over northeastern China. A combination of a negative phase of the interdecadal Pacific oscillation and a positive phase of the Atlantic multidecadal oscillation during 1999–2013 resulted in significant tropospheric warming over the low and high latitudes and cooling over the midlatitudes of East Asia. These changes enhanced the meridional temperature gradient and thus westerlies over the region between the two jets but weakened them to the south and north of it, thereby contributing to the wind change patterns and the jet displacements.

Rapid response of the East Asian trough to Tibetan Plateau snow cover

2020 ◽  
Vol 41 (1) ◽  
pp. 251-261 ◽  
Author(s):  
Wenkai Li ◽  
Bo Qiu ◽  
Weidong Guo ◽  
Pang‐chi Hsu
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
East Asian ◽  
Rapid Response ◽  
East Asian Trough ◽  
Tibetan Plateau Snow Cover
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