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- Title
Modeling impacts of dust mineralogy on Earth's Radiation and Climate.
- Authors
Qianqian Song; Ginoux, Paul; Ageitos, María Gonçalves; Miller, Ron L.; Obiso, Vincenzo; Pérez García-Pando, Carlos
- Abstract
Mineralogical composition drives diverse dust impacts on Earth's climate systems. However, most climate models still use fixed dust mineralogy, without accounting for its temporal and spatial variation. To quantify the radiative impact of resolving dust mineralogy on Earth's climate, we implement and simulate the distribution of dust minerals (i.e., illite, kaolinite, smectite, hematite, calcite, feldspar, quartz, and gypsum) from Claquin et al. (1999) (C1999) in the GFDL AM4.0 model. Resolving dust mineralogy reduces dust absorption and results in improved agreement with observation-based single scattering albedo (SSA), radiative fluxes from CERES (the Clouds and the Earth's Radiant Energy System), and land surface temperature from CRU (Climatic Research Unit), compared to the baseline bulk dust model version. It also results in distinct radiative impacts on Earth's climate over North Africa. Over the 19-year (from 2001 to 2019) modeled period during JJA (June-July-August), it leads to a reduction of over 50% in net downward radiation across the Sahara and approximately 20% over the Sahel at top of atmosphere (TOA). The reduced dust absorption weakens the atmospheric warming effect of dust aerosols and leads to an alteration in land surface temperature, resulting in a decrease of 0.4K over the Sahara and an increase of 0.6K over the Sahel. The less warming in the atmosphere suppresses ascent and weakens the monsoon inflow from the Gulf of Guinea. This brings less moisture to the Sahel, which combined with decreased ascent induces a reduction of precipitation. Interestingly, we find similar results by simply fixing the hematite content of dust to 0.9% by volume, which is more computationally efficient than simulating all minerals. However, uncertainties related to emission and distribution of minerals may blur the advantages of resolving minerals to study their impact on radiation, cloud properties, ocean biogeochemistry, air quality, and photochemistry. On the other hand, lumping together clay minerals (i.e., illite, kaolinite, and smectite), but excluding externally mixed hematite and gypsum, appears to provide both computational efficiency and relative accuracy. Nevertheless, for specific research, it may be necessary to fully resolve mineralogy to achieve accuracy.
- Subjects
SAHEL; SAHARA; GULF of Guinea; MINERAL dusts; DUST; TERRESTRIAL radiation; MINERALOGY; LAND surface temperature; SOLAR radiation; CLAY minerals
- Publication
Atmospheric Chemistry & Physics Discussions, 2023, p1
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/egusphere-2023-2938