Inconsistent aerosol indirect effects on water clouds and ice clouds over the Tibetan Plateau

Abstract

Recently, satellites have observed that dust events are occurring more frequently over the Tibetan Plateau (TP), which implies a new issue of aerosols influencing cloud properties and presents a new challenge in research on the role of the TP in climate change. In this study, combining satellite observations with Climate Model Intercomparison Project Phase 5 (CMIP5) model simulations, the inconsistent aerosol indirect effects on the properties of water clouds and ice clouds over the TP are compared and quantified. Analyses of satellite observations show that, compared with water clouds, ice clouds are observed more frequently and are more significantly correlated with aerosols over the TP. Correspondingly, the aerosol effect on the radiative forcing of ice clouds is more significant than that on the forcing of water clouds, in which the aerosol indirect effect is dominated by the effect on the shortwave radiative forcing of ice clouds. Both observations and CMIP5 model simulation results show that, due to the variation of aerosols, changes in the ice cloud radiative forcing cover most of the TP, while changes in the water cloud radiative forcing mainly appear over the southern edge of the TP. The CMIP5 simulation results suggest that the aerosol indirect effect on the total radiative forcing of water clouds over the TP is −0.34 (±0.03) W⋅m−2, while that on the forcing of ice clouds is −0.73 (±0.03) W⋅m−2. Overall, both the model simulations and satellite results show that the indirect effect of aerosols on ice clouds is more pronounced than that on water clouds.

Precipitation efficiency of cloud and its influencing factors over the Tibetan plateau

“…The occurrence frequency of ice clouds and water clouds is an important reference index to reveal the contribution of ice clouds and water clouds to precipitation. The occurrence frequency of ice clouds and water clouds in the marginal region of the TP is significantly higher than that in the main region of the TP, and the occurrence frequency of ice clouds and water clouds in the marginal region of the Plateau is even more than 90% (Hua et al ., 2019). The ice cloud fractions are mainly concentrated in the central part of the TP (Zhao et al, 2014; Liu et al ., 2019).…”

“…In the SETP, the frequency of ice cloud and water cloud is approximately 80% and 70%, respectively. In the NETP, the frequency of ice cloud and water cloud is approximately 70% and 55%, respectively (Hua et al ., 2019).…”

“…(2017) indicated that the IWP has a high correlation with surface precipitation in regions with a high occurrence frequency of ice clouds such as the tropical and mid‐latitude regions. The occurrence frequency of the ice cloud fraction over the TP was obviously higher than that of the water cloud (Liu et al ., 2019; Hua et al, 2019). The relatively higher correlation between the IWP and precipitation over the TP may be related to the higher occurrence probability of ice clouds.…”

“…In the TP, thermodynamic factors have a decisive influence on PE, and, aerosols, especially dust aerosols, also play a potential role in the formation and development of clouds and precipitation (Huang et al ., 2007; Liu et al ., 2019; Hua et al, 2019). The influence mechanism of atmospheric aerosols on precipitation and PE over the TP is still not clear and needs to be investigated in future studies.…”

Measurement report: quantifying source contribution of fossil fuels and biomass-burning black carbon aerosol in the southeastern margin of the Tibetan Plateau

“…The TP is covered by one of the largest ice masses on Earth, and it has been called the water tower of Asia (Liu et al, 2020b). The glaciers on the TP are facing rapid retreat, however, and if unchecked, this could result in adverse effects on the Asian hydrological cycle and Asian monsoon (Luo et al, 2020;Hua et al, 2019). In spring, the glaciers on the TP begin to melt as part of the natural hydrological cycle, but the increasing quantities of black carbon (BC) aerosol transported to the TP have accelerated this process (Bond et al, 2013) by causing a warming effect Published by Copernicus Publications on behalf of the European Geosciences Union.…”