Analysis on Meteorological Conditions during PM10 Pollution of Chengdu in 2012

Based on the daily PM10 data,sounding data of Chengdu and the 2.5° ×2.5° nalysis data of NCEP,the analysis on meteorological conditions,including circulation background,dynamic conditions,stability conditions and moisture conditions,were carried out against thirteen typical PM10 pollution processes.The results indicate that:1) Sichuan Province is usually controlled by the westerly flow or northwest flow during PM10 pollution process,with the South Wave being weak.2) The vertical motion in the middle and lower atmosphere is weak,with slight convergence in the relatively low level,which is unfavorable to the horizontal and vertical diffusion of pollutants.3) The atmosphere is rather stable with a temperature inversion or isothermal layer in the lower troposphere.4) The humidity layer is shallow when the upper air is relatively dry.