Anthropogenic pollutants could enhance aridity in the vicinity of the Taklimakan Desert: A case study.

With the intensification of human activities, the mixture of anthropogenic pollutants and natural dust aerosols in the vicinity of the Taklimakan Desert (TD) has become a new uncertainty in the weather and climate system. In this study, using a Weather Research and Forecasting model version 4.0 with the Thompson aerosol-aware microphysics scheme, we investigated the impact of anthropogenic aerosols on clouds and precipitation in an atmospheric environment with abundant dust aerosols in the vicinity of the TD. Our findings indicate that anthropogenic aerosols can increase cloud droplet number concentrations in the vicinity of the TD, and the maximum percentage increase can reach 50 %. In addition, the effective radius of water clouds decreases significantly due to anthropogenic aerosols, which means that more numerous but smaller cloud droplets are formed with enhanced anthropogenic aerosol loading under a dusty background. Meanwhile, anthropogenic aerosols can decrease raindrops below 650 hPa, graupel and snow particles, causing less precipitation in the dusty atmosphere surrounding the TD. Furthermore, the anthropogenic aerosol-induced changes in daily precipitation accumulation are also large, with a regionally averaged maximum reduction of up to 4.2 %. Therefore, anthropogenic aerosols are an important factor that exacerbates aridity in the vicinity of the TD, and there is an urgent need to control anthropogenic pollutants around the TD.

Role of anthropogenic aerosols in affecting different-grade precipitation over eastern China: A case study.

Atmospheric aerosols play an important role in affecting clouds and precipitation by serving as condensation/ice nuclei. However, how to quantify the contribution of anthropogenic aerosols to the alteration of clouds and precipitation remains unknown. In this study, using a Weather Research and Forecasting-Chemistry (WRF-Chem) model, we quantified the impacts of anthropogenic aerosols on cloud water properties under different precipitation grades during a single rainfall event over eastern China. The results of this study show that anthropogenic aerosols have varying effects on hourly precipitation with heavy (greater than 1.04 mm/h), moderate (0.41-1.04 mm/h), and light (less than 0.41 mm/h) grades. Due to the presence of anthropogenic aerosols, heavy precipitation is intensified by 70.96%; however, moderate and light precipitation is further weakened by 24.87% and 86.43%, respectively. For heavy precipitation, the addition of anthropogenic aerosols induces an enhancement in upward motion, increases the cloud water path and effective radius through the aerosol-radiation interaction (ARI) effect, which is the main reason for the intensification of heavy-grade precipitation. In addition, the weakened upward motion and decreased ice water path caused by ARI and aerosol-cloud interaction (ACI) effects play common roles in reducing moderate and light precipitation. Studying anthropogenic aerosols' impacts on precipitation is of great importance for understanding the influence of anthropogenic pollution on the weather and climate and even for promoting precipitation forecasting and prediction.