Trajectory modeling of modern dust transport to the Southern Ocean and Antarctica

Abstract

Aerosol deposition over the Southern Ocean and Antarctica has the potential to alter marine productivity and thus ocean carbon uptake while also impacting radiative balance due to scattering and absorption from atmospheric particulates. Quantification of modern emission, transport, and deposition of terrestrial dust and other airborne material from Southern Hemisphere sources is challenging due to low emission levels and poor detection from remote sensing platforms. Here forward trajectory modeling is used to explore atmospheric transport, independent of deposition processes, from 1979 to 2013. Trajectories are initiated from known arid dust source areas in South America (Patagonia), Australia, and southern Africa, with detailed consideration of New Zealand as a potential source. Results suggest that Patagonian and New Zealand dust and other aerosol emissions share strong atmospheric transport during all seasons, allowing even potentially small New Zealand emissions to contribute significantly to Southern Ocean and Antarctic aerosol loading. We find that atmospheric transport controlling distribution of dust and other aerosols shows distinct spatial variability. New Zealand and Patagonia rapidly contribute a high proportion of trajectories to West Antarctica, while in interior East Antarctica, source contributions are limited and highly mixed. The sensitivity of existing deep ice core sites to modern atmospheric transport is discussed. Finally, interannual variability of poleward trajectory extension over the Pacific and Atlantic sectors of the Southern Ocean highlights the association of both tropical Pacific sea‐surface temperature and high‐latitude wind variability (e.g., the Southern Annular Mode) with transport of dust and other aerosols to the Southern Ocean and Antarctica.

Antarctic climate variability on regional and continental scales over the last 2000 years

“…Victoria Lower Glacier, to the east of RICE) show a clear cooling trend prior to 1900 CE, and together this points to a more complex picture of the evolution of the atmospheric circulation around the Ross Sea than can be captured with the current network of cores. The RICE δ 18 O record, situated on Roosevelt Island on the Ross Ice Shelf, is more influenced by air masses from the eastern Ross Sea sector than the rest of the West Antarctic Ice Sheet region, which is influenced predominantly by air masses from the Amundsen Sea (Neff et al, 2015;. Moreover, borehole temperature and δ 15 N thermal fractionation records at RICE highlight some notable differences in the isotope temperature reconstruction, which suggest that sea ice extent exerts an important control, perhaps masking aspects of the longer-term temperature trends in the region .…”

The distribution and biogeochemical importance of high‐latitude dust in the Arctic and Southern Ocean‐Antarctic regions

“…[] suggest that dust originating at latitudes >60°N accounts for 27% of the total atmospheric dust load in the Arctic, with 38% being transported to the region from Asia and a farther 32% from Africa. Using air parcel trajectory modeling of atmospheric transport pathways, Neff and Bertler [] concluded that the high‐latitude dust sources in New Zealand and Patagonia were more likely to contribute dust to the Southern Ocean and Antarctica than sources in subtropical southern Africa or Australia. An important result of Neff and Bertler 's [] study concerns the potential vertical profile of dust in the atmosphere.…”

Mapping Areas of the Southern Ocean Where Productivity Likely Depends on Dust‐Delivered Iron

“…During atmospheric transport, the dust could be deposited via dry and wet deposition (Mahowald et al, ); however, the actual deposition processes are not explored in this study. Other studies have shown that the accuracy of HYSPLIT trajectories based on reanalysis data is robust and highly correlated with station measurements in the Southern Hemisphere (Neff & Bertler, ). HYSPLIT provides an opportunity to simulate the long‐range transport of dust emitted by continental sources that are included in this study.…”