Effect of Aerosols on the Ice Cloud Properties Over the Tibetan Plateau

Abstract

With the highlight of environmental problems over the Tibetan Plateau (TP), aerosol pollution and the influence of this pollution on cloud properties are becoming a new area of research. Based on the aerosol index and cloud property parameters derived from satellite observations, in this study, the inconsistent effects of aerosols on ice cloud properties between daytime and nighttime over the TP are investigated. The results indicate that ice clouds are mainly distributed over the TP margin area, especially over the north slope, during both daytime and nighttime. The occurrence frequency of ice cloud is higher during the daytime than during the nighttime over the margin areas of the TP. Similarly, aerosols are mainly concentrated over the northern margin of the TP. A potential relationship may exist between the aerosol index and ice cloud properties. When the aerosol index increases from 0.05 to 0.17, the ice cloud droplet radius (ICDR) during the daytime decreases from 32.1 to 27.9 μm, while the ICDR during the nighttime remains almost constant (approximately 25 μm); furthermore, the ice water path (IWP) during the daytime decreases slightly due to the saturation effect, while the nocturnal IWP increases significantly. The changes in ice cloud optical depth (ICOD) during daytime and nighttime show significant and completely opposite trends. The removal of the influence of meteorological factors showed that aerosols have a more dominant influence than meteorological conditions on ice cloud properties (except for the nocturnal ICDR and IWP during the daytime).