Weaker cooling by aerosols due to dust-pollution interactions

Abstract

Abstract. The interactions between aeolian dust and anthropogenic air pollution, notably chemical ageing of mineral dust and coagulation of dust and pollution particles, modify the atmospheric aerosol composition and burden. Since the aerosol particles can act as cloud condensation nuclei, this not only affects the radiative transfer directly via aerosol-radiation interactions, but also indirectly through cloud adjustments. We study both radiative effects using the global ECHAM/MESSy atmospheric chemistry-climate model (EMAC) which combines the Modular Earth Submodel System (MESSy) with the European Centre/Hamburg (ECHAM) climate model. Our simulations show that dust-pollution interactions reduce the cloud water path and hence the reflection of solar radiation. The associated climate warming outweighs the cooling which the dust-pollution interactions exert through the direct radiative effect. In total, this results in a net warming by dust-pollution interactions which moderates the negative global anthropogenic aerosol forcing at the top of the atmosphere by (0.2 ± 0.1) W m−2.

Dust-Dominated Coarse Particles as a Medium for Rapid Secondary Organic and Inorganic Aerosol Formation in Highly Polluted Air

“…Although mineral components can promote many heterogeneous SA formation routes, their SA production is typically limited by available reactive surface areas, which is why fresh dry dust usually does not show large contributions to SA formation . However, the morphology of dust may change during its aging process, , especially under higher RH conditions, forming solid cores with aqueous shells, which has been proposed to increase its heterogeneous reactivity and thus might promote SA formation processes thereon . Aged dust particles normally reveal significantly stronger water adsorption capabilities, especially those with nitrate coatings can become aqueous droplets even when the RH is below 30% .…”

“…In addition, dust particles often act as ice nuclei for ice cloud formation. The large amounts of SA formed on coarse particles might change cloud properties or their ability to act as ice nuclei, which, however, has been rarely studied. Currently, it is believed that inorganic coating such as that of sulfate and nitrate mainly suppress a dust particle’s ability to serve as ice nuclei, while different organic coatings on different seed dust particles might suppress/enhance their ice nucleating abilities to different degrees, depending also on the RH and temperature regime. ,− However, how simultaneous formation of organic and inorganic SAs on dust modifies its ice nucleating ability remains to be investigated.…”

Climate Change and Weather Extremes in the Eastern Mediterranean and Middle East

“…The uptake of acids tends to reduce the lifetime of dust particles by enhancing the deposition and cloud scavenging efficiency (Abdelkader et al., 2015). Since aerosols act as cloud condensation nuclei, dust‐pollution‐cloud interactions cause cloud adjustments, which reduce the condensed water path, leading to a positive (warming) radiative forcing of climate (Klingmüller et al., 2020).…”

Mineral dust aerosol impacts on global climate and climate change

“…The abundance and long-range transport of dust cause it to impact climate through various mechanisms. During transport, dust scatters and absorbs solar shortwave (SW) and terrestrial longwave (LW) radiation 7,12 , modifies cloud properties through seeding cloud droplets and ice crystals 13,14 , mixes with other aerosols 15 and serves as a sink for radiatively important atmospheric trace gases [15][16][17][18] . On deposition, dust darkens snow and ice packs 19,20 and stimulates ecosystem productivity 42 ); emissions from high-latitude regions are not included.…”