Investigation of the effect of anthropogenic pollution on typhoon precipitation and microphysical processes using WRF-Chem

Abstract:

This letter presents an analysis of the influence of anthropogenic aerosols on typhoon, with Usagi as an example, using the Weather Research and Forecasting Model with Chemistry (WRF-Chem). Three simulations (CTL, CLEAN, EXTREME) were designed according to the emission intensity of anthropogenic pollution. The results showed that although anthropogenic pollution did not have a clear influence on typhoon track and strength, it clearly changed precipitation, the distribution of water hydrometeors, and microphysical processes. In the CLEAN experiment, precipitation rate declined because of cloud water collected by rain decreased. Similarly, precipitation rate decreased in the EXTREME experiment, because cloud water auto-conversion to rain water was restrained. Regarding precipitation type, stratiform precipitation rate in the CLEAN and EXTREME simulations was suppressed because the ice phase microphysical processes weakened. Compared to CTL run, stratiform precipitation rate at the periphery was reduced by about 28% in CLEAN and EXTREME simulations. Moreover, convective precipitation rate annulus 140-160km in EXTREME experiment was about 33% larger than that in CTL simulation. It was triggered new convection at the periphery in EXTREME simulation due to cloud water re-evaporation. Finally, compared to the CTL experiment, rainfall peaks of convective and mixed precipitation type in the CLEAN and EXTREME experiments shifted 10km toward the typhoon periphery.