TY - JOUR
T1 - Mechanisms contributing to suppressed precipitation in Mt. Hua of central China. Part I
T2 - Mountain valley circulation
AU - Yang, Yan
AU - Fan, Jiwen
AU - Leung, L. Ruby
AU - Zhao, Chun
AU - Li, Zhanqing
AU - Rosenfeld, Daniel
N1 - Publisher Copyright:
© 2016 American Meteorological Society.
PY - 2016/3/1
Y1 - 2016/3/1
N2 - A significant reduction in precipitation in the past decades has been documented over many mountain ranges such as those in central and eastern China. Consistent with the increase of air pollution in these regions, it has been argued that the precipitation trend is linked to the aerosol microphysical effect on suppressing warmrain.Rigorous quantitative investigations on the reasons responsible for the precipitation reduction are lacking. In this study, an improved Weather Research and Forecasting (WRF) Model with online coupled chemistry (WRF-Chem) is applied and simulations are conducted at the convectionpermitting scale to explore the major mechanisms governing changes in precipitation from orographic clouds in theMt. Hua area in central China. It is found that anthropogenic pollution contributes to a ;40% reduction of precipitation over Mt. Hua during the 1-month summertime period. The reduction is mainly associated with precipitation events associated with valley-mountain circulation and a mesoscale cold-front event. In this paper (Part I), the mechanism leading to a significant reduction for the cases associated with valley-mountain circulation is scrutinized. It is found that the valley breeze is weakened by aerosols as a result of absorbing aerosol-induced warming aloft and cooling near the surface as a result of aerosol- radiation interaction (ARI). The weakened valley breeze and the reduced water vapor in the valley due to reduced evapotranspiration as a result of surface cooling significantly reduce the transport of water vapor from the valley to mountain and the relative humidity over the mountain, thus suppressing convection and precipitation in the mountain.
AB - A significant reduction in precipitation in the past decades has been documented over many mountain ranges such as those in central and eastern China. Consistent with the increase of air pollution in these regions, it has been argued that the precipitation trend is linked to the aerosol microphysical effect on suppressing warmrain.Rigorous quantitative investigations on the reasons responsible for the precipitation reduction are lacking. In this study, an improved Weather Research and Forecasting (WRF) Model with online coupled chemistry (WRF-Chem) is applied and simulations are conducted at the convectionpermitting scale to explore the major mechanisms governing changes in precipitation from orographic clouds in theMt. Hua area in central China. It is found that anthropogenic pollution contributes to a ;40% reduction of precipitation over Mt. Hua during the 1-month summertime period. The reduction is mainly associated with precipitation events associated with valley-mountain circulation and a mesoscale cold-front event. In this paper (Part I), the mechanism leading to a significant reduction for the cases associated with valley-mountain circulation is scrutinized. It is found that the valley breeze is weakened by aerosols as a result of absorbing aerosol-induced warming aloft and cooling near the surface as a result of aerosol- radiation interaction (ARI). The weakened valley breeze and the reduced water vapor in the valley due to reduced evapotranspiration as a result of surface cooling significantly reduce the transport of water vapor from the valley to mountain and the relative humidity over the mountain, thus suppressing convection and precipitation in the mountain.
UR - http://www.scopus.com/inward/record.url?scp=84962242265&partnerID=8YFLogxK
U2 - 10.1175/JAS-D-15-0233.1
DO - 10.1175/JAS-D-15-0233.1
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AN - SCOPUS:84962242265
SN - 0022-4928
VL - 73
SP - 1351
EP - 1366
JO - Journal of the Atmospheric Sciences
JF - Journal of the Atmospheric Sciences
IS - 3
ER -