Abstract
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 cycle. 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 cycle 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 modeling 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 focusing 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. However, contrary to previous studies, we find that Australia contributes a higher proportion during the LGM, which is mainly caused by changes in the precipitation patterns. Obtained increased 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 consequence of reduced convection due to colder surfaces, indicating a vertically less extensive Polar cell.
Highlights
In the last few decades, mineral dust has been identified as playing an important role in the climate system due to its various interactions in atmospheric processes (e.g., Maher et al, 2010)
Our model performs at the lower end of the 1000– 4000 Tg yr−1 range of dust emissions estimated by the IPCC (Intergovernmental Panel on Climate Change, 2014), which is caused by the neglect of a super-coarse particle mode (Stanelle et al, 2014)
ECHAM6.3-HAM2.3 constitutes a state-of-the-art model providing an interactive coupling of mineral dust emissions to the atmospheric model depending on surface properties and meteorological factors
Summary
In the last few decades, mineral dust has been identified as playing an important role in the climate system due to its various interactions in atmospheric processes (e.g., Maher et al, 2010). The characteristic isotope ratios of 87Sr/86Sr and 143Nd/144Nd of mineral dust found in Antarctic ice cores and delivered during interglacials match those of southern South American soil samples and the ratio of soil samples from central and southeastern Australia (De Deckker et al, 2010) This finding suggests that transport of Australian dust to Antarctica is generally possible and raises the question if and to what degree Australian dust sources might have contributed to the total amount of dust found in ice cores during glacials and which climate elements caused the according changes. We use the combined global and local information on particle sizes and lifetimes, as well as precipitation and wind patterns, to draw conclusions concerning the atmospheric circulation in the Southern Hemisphere during the LGM
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
