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Impact of soil freezing-thawing processes on August rainfall over southern China
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  • Kun Xia,
  • Lijuan Li,
  • Yan li Tang,
  • Bin Wang
Kun Xia
LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences

Corresponding Author:xiakun@lasg.iap.ac.cn

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Lijuan Li
LASG,IAP Chines Academy of Sciences
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Yan li Tang
State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences
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Bin Wang
LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences
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In this study, the impact of soil freezing–thawing processes on August rainfall in southern China (SC) during 1979–2008 and related physical mechanisms are investigated using the Grid-Point Atmospheric Model version 2.0 (GAMIL2.0). This model with considering the supercooled water in soil freezing-thawing scheme reproduces the climatology and trends of August precipitation in the SC region. Moisture-budget analysis is employed to quantity the contributions of different factors to the change of precipitation in SC. The results indicate that evaporation contributes significantly to the climatologically August rainfall in SC. The dynamic component of vertical moisture advection, which is related to changes in atmospheric circulation, plays an important role in August precipitation trends. The possible physical mechanism is that the GAMIL2.0 considering the supercooled water simulated much higher soil/air temperature on August especially in the north of 40°N, weakened the meridional thermal contrast, decreased the 200hpa zonal winds, strengthened 850hpa northerly wind, which is more benificial to the convergence in SC and lead to the precipitation increased. This study provides a new interpretation of the ‘southern flooding’ during 1979–2008 from the point of frozen soil changing.
27 Apr 2022Published in Journal of Geophysical Research: Atmospheres volume 127 issue 8. 10.1029/2021JD036302