Type-Dependent Impact of Aerosols on Precipitation Associated with Deep Convective Cloud over East Asia

Abstract:

Aerosol-cloud-precipitation interactions remain one of the largest uncertainties in climate simulation and projection. In particular, the impact of aerosols on precipitation is highly uncertain due to limited and conflicting observational evidence. A major challenge is to distinguish the effects of different types of aerosol on precipitation associated with deep convective clouds, which produces most of the precipitation in East Asia. Here, we use 9-year observations from multiple satellite-borne sensors and find that the frequency of heavy rain increases while that of light rain decreases with the increase of Aerosol Optical Depth (AOD) for dust and anthropogenic aerosol types. For rain amount, elevated smoke tends to suppress annual mean deep convective precipitation, while dust and polluted continental aerosols show an invigoration effect. The invigoration effect is more significant for clouds with higher cloud base temperature (CBT), while no significant invigoration is observed when CBT is less than 12℃. A big difference is found for the response of precipitation amount to AOD between land and ocean. While the prevailing continental aerosol types other than smoke invigorate deep convection and increase precipitation, the main aerosol types over ocean first enhance and then inhibit precipitation with the increase of AOD. Moreover, our analysis indicates that the above inhibition and invigoration effects on precipitation are mainly caused by aerosols themselves, rather than by meteorological factors. These observed relationships between different aerosol types and precipitation frequency and amount provide valuable constraints on the model forecasting of precipitation.