Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Disproportionate Control on Aerosol Burden by Light Rain

TitleDisproportionate Control on Aerosol Burden by Light Rain
Publication TypeJournal Article
Year of Publication2021
JournalNature Geoscience
Abstract / Summary

Atmospheric aerosols are of great climatic and environmental importance due to their effects on the Earth’s radiative energy balance and air quality. Aerosol concentrations are strongly influenced by rainfall via wet removal. Global climate models have been used to quantify their climate and health effects. However, they commonly suffer from a well-known problem of ‘too much light rain and too little heavy rain’. The impact of simulated rainfall intensities on aerosol burden at the global scale is still unclear. Here we show that rainfall intensity has profound impacts on aerosol burden, and light rain has a disproportionate control on it. By improving the representation of convection, the light-rain (1–20 mm d−1) frequency in two state-of-the-art global climate models is reduced. As a result, the aerosol burden is increased globally, especially over the tropics and subtropics, by as much as 0.3 in aerosol optical depth in tropical rain belts. It is attributed to the dominant contribution of light rain to the accumulated wet removal by its frequent occurrence despite its weak intensity. The implication of these findings is that understanding the nature of aerosol scavenging by rainfall is critical to aerosol–climate interaction and its impact on climate.

URLhttp://dx.doi.org/10.1038/s41561-020-00675-z
DOI10.1038/s41561-020-00675-z
Journal: Nature Geoscience
Year of Publication: 2021
Publication Date: 01/2021

Atmospheric aerosols are of great climatic and environmental importance due to their effects on the Earth’s radiative energy balance and air quality. Aerosol concentrations are strongly influenced by rainfall via wet removal. Global climate models have been used to quantify their climate and health effects. However, they commonly suffer from a well-known problem of ‘too much light rain and too little heavy rain’. The impact of simulated rainfall intensities on aerosol burden at the global scale is still unclear. Here we show that rainfall intensity has profound impacts on aerosol burden, and light rain has a disproportionate control on it. By improving the representation of convection, the light-rain (1–20 mm d−1) frequency in two state-of-the-art global climate models is reduced. As a result, the aerosol burden is increased globally, especially over the tropics and subtropics, by as much as 0.3 in aerosol optical depth in tropical rain belts. It is attributed to the dominant contribution of light rain to the accumulated wet removal by its frequent occurrence despite its weak intensity. The implication of these findings is that understanding the nature of aerosol scavenging by rainfall is critical to aerosol–climate interaction and its impact on climate.

DOI: 10.1038/s41561-020-00675-z
Citation:
Wang, Y, W Xia, X Liu, S Xie, W Lin, Q Tang, H Ma, Y Jiang, B Wang, and GJ Zhang.  2021.  "Disproportionate Control on Aerosol Burden by Light Rain."  Nature Geoscience.  https://doi.org/10.1038/s41561-020-00675-z.