Aircraft observation of fast initiation of mixed phase precipitation in convective cloud over the Tibetan Plateau

Abstract

The Tibetan Plateau is known as the water tower of Southeast Asia, and precipitation processes on the Tibetan Plateau is complex, especially in convective cloud precipitation. Many remote sensing and ground observations have been analyzed, but the in-situ measurements of cloud microphysical characteristics are rare. Here we present aircraft observations of the microphysics of convective clouds over the Qinghai Tibet Plateau in China. These results show the microphysical structure of convective clouds and the triggering characteristics of precipitation in summer in Tibet. The vertical profile of July 9th was selected for a detailed analysis of microphysical characteristics. Mixed phase precipitation was initiated above the 7000 m above sea level over the TP, which is only about 500 m above cloud base height. Riming was the dominant precipitation forming process over the TP, leading to graupel formation, which was the primary form of precipitation of the convective clouds. Although the dust was a large fraction of the overall aerosols over the TP during the flights, it was not likely a major contribution to the early ice formation because of the temperature limit of the Ice Nuclei (IN) parameterization. The secondary ice process (SIP) appears to be the main source of ice crystals.