Direct radiative effect of dust-pollution interactions

Abstract

<p><strong>Abstract.</strong> The chemical ageing of aeolian dust, through interactions with air pollution, affects the optical and hygroscopic properties of the mineral particles and hence their atmospheric residence time and climate forcing. Conversely, the chemical composition of the dust particles and their role as coagulation partners impact the abundance of particulate air pollution. This results in an anthropogenic radiative forcing associated with mineral dust notwithstanding the natural origin of most aeolian dust. Using the atmospheric chemistry climate model EMAC with a detailed parametrisation of ageing processes and an emission scheme accounting for the chemical composition of desert soils, we study the direct radiative forcing globally and regionally. Our results indicate large positive and negative forcings, depending on the region. The predominantly negative forcing at the top of the atmosphere over large parts of the dust belt, from West Africa to East Asia, attains a maximum of about −2 W/m<sup>2</sup> south of the Sahel, in contrast to a positive forcing over India. Globally averaged, these forcings partially counterbalance, resulting in a net negative forcing of −0.05 W/m<sup>2</sup>, which nevertheless represents a considerable fraction of the total dust forcing.</p>

Influence of Saharan Dust on the Large‐Scale Meteorological Environment for Development of Tropical Cyclone Over North Atlantic Ocean Basin

“…These effects are clearly observed at approximately 700–850 hPa with the weakening of heating from the underlying surfaces and we thus infer that the dust radiation effects could be even stronger at lower levels due to the presence of more dust aerosols if the thermal transportation were removed. This inference has been confirmed by many modeling studies (e.g., Klingmüller et al, 2019; Martínez Avellaneda et al, 2010) but some simulations have shown cooling effects at 600–800 hPa over the ocean (e.g., Bretl et al, 2015) which was not observed in this study and the exact mechanism has not been determined. Martínez Avellaneda et al (2010) have shown high correlations between SST and AOD after removing the seasonal climatological cycle and dynamic circulation from ocean circulation model simulations while the correlations (+/−) are sensitive to different regions.…”

Effects of fossil fuel and total anthropogenic emission removal on public health and climate

“…Our total direct plus indirect radiative forcing is −0.9 W/m 2 , which also agrees with IPCC (11). However, by also accounting for the chemical aging of aeolian dust by air pollution we obtain a −0.3-W/m 2 larger effect, about −1.2 ± 0.06 W/m 2 (28, 29). The dust aging has multiple consequences, such as increased solar radiation scattering from hygroscopic particle growth and decreased lifetime from more efficient rainout, while the climate effect is dominated by the enhanced CCN activity.…”