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Impact of the Eurasian wave train on Autumn Precipitation in the Central Region of China
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  • Linwei Jiang,
  • Baohua Ren,
  • Cen Wang,
  • Chao Zhang
Linwei Jiang
University of Science and Technology of China

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Baohua Ren
University of Science and Technology of China
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Cen Wang
University of Science and Technology of China
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Chao Zhang
Xiamen University
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Abstract

The autumn precipitation in the central region of China (APCC) can exert great influences to the production and people’s livelihood. With the use of reanalysis data from 1979−2020, we found a simultaneous relationship between the interannual variability of APCC and the second mode of the 200-hPa meridional wind field over the Eurasian continent, which featured a ‘+-+’ wave-like pattern in autumn (denoted by EC-a). When EC-a is in a positive phase, the coupling of the positive geopotential height with anticyclonic anomalies in the upper level and low sea level pressure over the central China provides a conducive moisture and dynamic condition for precipitation, which is reversed in the negative phase. As indicated by the diagnostic equation, the local vertical motion anomaly is mainly dependent on the temperature advection anomaly by the perturbed wind acting on mean temperature. The strengthened anticyclonic wind shear over East Asia reinforces the southeasterly, which induces warmer air to move northward, resulting in a positive temperature advection and hence enhancing local ascending motion. Moreover, wave flux analysis and numerical simulations show that the EC-a wave train could be triggered by an abnormal dipole pattern SST over the North Atlantic Ocean, which acts as a critical pacemaker on the variability of EC-a.