Simulating glacial dust changes in the Southern Hemisphere using ECHAM6.3-HAM2.3


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stephan.kraetschmer [ at ] awi.de

Abstract

Mineral dust aerosol constitutes an important component of the Earth’s climate system, not only on short timescales due to direct and indirect influences on the radiation budget but also on long timescales by acting as a fertilizer for the biosphere and thus affecting the global carbon cy- cle. For a quantitative assessment of its impact on the global climate, state-of-the-art atmospheric and aerosol models can be utilized. In this study, we use the ECHAM6.3-HAM2.3 model to perform global simulations of the mineral dust cy- cle for present-day (PD), pre-industrial (PI), and last glacial maximum (LGM) climate conditions. The intercomparison with marine sediment and ice core data, as well as other mod- eling studies, shows that the obtained annual dust emissions of 1221, 923, and 5159 Tg for PD, PI, and LGM, respectively, generally agree well with previous findings. Our analyses fo- cusing on the Southern Hemisphere suggest that over 90 % of the mineral dust deposited over Antarctica are of Australian or South American origin during both PI and LGM. How- ever, contrary to previous studies, we find that Australia con- tributes a higher proportion during the LGM, which is mainly caused by changes in the precipitation patterns. Obtained in- creased particle radii during the LGM can be traced back to increased sulfate condensation on the particle surfaces as a consequence of longer particle lifetimes. The meridional transport of mineral dust from its source regions to the South Pole takes place at different altitudes depending on the grain size of the dust particles. We find a trend of generally lower transport heights during the LGM compared to PI as a con- sequence of reduced convection due to colder surfaces, indi- cating a vertically less extensive Polar cell.



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Helmholtz Cross Cutting Activity (2021-2027)
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Peer-reviewed, Web of Science / Scopus
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Published
Eprint ID
55658
DOI 10.5194/cp-18-67-2022

Cite as
Krätschmer, S. , van der Does, M. , Lamy, F. , Lohmann, G. , Völker, C. and Werner, M. (2022): Simulating glacial dust changes in the Southern Hemisphere using ECHAM6.3-HAM2.3 , Climate of the Past, 18 (1), pp. 67-87 . doi: 10.5194/cp-18-67-2022


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