Comparison of the impacts due to biomass burning, anthropogenic, and biogenic aerosol emissions on the mature phase of an urban heavy precipitation event over the Pearl River Delta

The study is aimed to discuss the differences in the aerosol impacts on the precipitation in mature phase due to three different aerosol emission sources, the biomass burning emission (BB), the anthropogenic emission (AE), and the biogenic emission (BE). Four simulations were conducted using WRF-Chem version 4.1.2 on the heavy urban precipitation event over the Pearl River Delta (PRD) region, which occurred on 21 February 2019, with 0800-0900 UTC 21 February as the mature phase. The inclusion of aerosol emissions improved the simulation performance on the temporal variations of the precipitation event and the peak precipitation. BB, AE, and BE contributed to the aerosol loading by around 6.8%, 88.1%, and 5.1%, respectively; and weakened the precipitation 28.0%, 31.0%, and 14.1%, respectively. The BE impact occurred the latest during the developing phase. The weakening effect was mainly over the convective precipitation. The aerosol indirect effect of BE strengthened the stratiform precipitation. The weakened convective precipitation was contributed by the weakened cloud microphysical processes above the zero-isotherm line. The BB impact induced the smallest change in cloud microphysical latent heating and weakened the precipitation more likely via its aerosol direct effect. The AE impact was the largest in precipitation, convection, and the cloud microphysical latent heating.