Changes in the diurnal variations of clouds and precipitation induced by anthropogenic aerosols over East China in August 2008

Özet

We investigated the impacts of all anthropogenic aerosols and black carbon (BC) on the diurnal variations ofcloud and precipitation over East China during August 2008 using a coupled meteorology and chemistry model(WRF-Chem). Comparison of the model results with observations showed that the model reproduced reasonablywell the distribution patterns of the aerosol optical depth (AOD), the horizontal wind, precipitation, and theliquid water path (LWP). The results from ensemble numerical experiments showed the aerosol-induced clouddroplet number concentration (CDNC) increased by 20–160 cm−3 over East China. The aerosol-induced cloudfraction (CF) increased by 0.03–0.08 below 850 hPa and at around 750 hPa over East China; it decreased by upto 0.06 between 750 and 850 hPa at around 25°N and over Central China. These increases were larger at earlymorning and nighttime, whereas the decreases were larger in the afternoon and evening. Other scatteringaerosols were the main contributor to the increase of CDNC and offset the decrease induced by BC. The decreaseof CF over Central China was mainly caused by BC. The precipitation induced by aerosols decreased by20–200 mm over South and North China with the largest decrease over the North China Plain and southwestChina. There was an increase of 20–100 mm over Central China. The decrease in precipitation over South andNorth China mainly occurred during the day, whereas the increase in precipitation over Central China mainlyoccurred at night which was caused by BC.