Effects of wintertime polluted aerosol on cloud over the Yangtze River Delta: case study

Abstract. The effects of polluted aerosol on cloud are examined over the Yangtze River Delta (YRD) using three-month satellite data during wintertime from December 2013 to January 2014. The relationships between aerosol properties and cloud parameters are analyzed in detail to clarify the differences of cloud development under varying aerosol and meteorology conditions. Complex relationships between aerosol optical depth (AOD) and cloud droplet radius (CDR), liquid water path (LWP) and cloud optical thickness (COT) exists in four sub-regions. High aerosol loading (AOD) does not obviously affect the distributions of cloud LWP and COT. In fact, an inhibiting effect of aerosol occurs in coastal area for low- and medium-low clouds, more pronounced in low clouds (< 5km) than high clouds. Low aerosol loading (AOD) plays a positive role in promoting COTs of high- and low-clouds in areas dominated by marine aerosol. The most significant effect presents in valley and coal industry districts for clouds except high-cloud. The smallest values and variations of cloud parameters are observed in dry-polluted area, which suggests that dust aerosol makes little difference on clouds properties. Synoptic conditions also cast strong impacts on cloud distribution, particularly the unstable synoptic condition leads to cloud development at larger horizontal and vertical scales. The ground pollution enhances the amount of low-level cloud coverage even under stable condition. Aerosol plays an important role in cloud evolution for the low layers of troposphere (below 5 km) in case of the stable atmosphere in wintertime.