Diurnal Evolution of Cloud Water Responses to Aerosols

Clouds play an essential role in the global energy budget, but the impact of anthropogenic aerosols on clouds is still poorly understood. We use 15-min temporal resolution geostationary satellite data to study the temporal evolution of polluted cloud tracks detected in the European part of Russia. Previous analysis of polluted cloud tracks shows that cloud water response to aerosols is bidirectional. Here, we show that cloud water gradually increases in the afternoon for polluted clouds in some cases. Aerosol-induced cloud thickening is much more likely in the case of thin unpolluted clouds. However, on average, there is less cloud water in the polluted clouds compared to the nearby unpolluted clouds. The temporal evolution of cloud thinning is not observed, and polluted clouds are thinner than the nearby unpolluted clouds since the early morning. The physical mechanisms leading to the observed changes and the influence of retrieval bias on the detected changes need further clarification. Our findings highlight the need to research the temporal evolution of cloud responses to aerosols to estimate the aerosol radiative forcing more accurately.