Dust Aerosol Impacts on the Time of Cloud Formation in the Badain Jaran Desert Area

Abstract

AbstractDust, as absorbing aerosols, can change the stability of the atmosphere through radiative effects, thereby affecting the formation and characteristics of clouds. In order to explore the influence of dust aerosols on cloud formation, this study takes the Badain Jaran Desert area as the research area where cloud formation is less disturbed by human activities compared to other densely populated areas such as the North China Plain, and uses the high temporal resolution Himawari‐8 satellite data to identify 469 cases with cloud formation after 03:00 UTC (11:00 Beijing time). Through the analysis of individual cases, we find that the cloud formation time is dominated by the low tropospheric stability (LTS) when the total precipitable water (TPW) is less than about 18.5 kg/m2, and greatly affected by the TPW when it is larger than 18.5 kg/m2. Dust aerosols near the ground absorb shortwave solar radiation, making the atmospheric structure unstable (decreased LTS) and conducive to cloud formation. Statistically, for every 0.1 increase in aerosol optical depth, the cloud formation time is advanced about 138 min compared to low aerosol cases. Further analysis shows that dust aerosols actually inhibit the formation of convective clouds through microphysical processes when the TPW is small, while promote the formation of convective clouds through radiative processes when the TPW is large. This study reveals the effects of dust aerosols on the time of cloud formation along with the underlying mechanisms, which provides observational support for improving cloud parameterization in numerical models.