| 1. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
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| 3. |
- Spolaor, A., et al.
(författare)
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Seasonality of halogen deposition in polar snow and ice
- 2014
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14, s. 9613-9622
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Tidskriftsartikel (refereegranskat)abstract
- The atmospheric chemistry of iodine and bromine in Polar regions is of interest due to the key role of halogens in many atmospheric processes, particularly tropospheric ozone destruction. Bromine is emitted from the open ocean but is enriched above first-year sea ice during springtime bromine explosion events, whereas iodine emission is at- tributed to biological communities in the open ocean and hosted by sea ice. It has been previously demonstrated that bromine and iodine are present in Antarctic ice over glacial– interglacial cycles. Here we investigate seasonal variability of bromine and iodine in polar snow and ice, to evaluate their emission, transport and deposition in Antarctica and the Arc- tic and better understand potential links to sea ice. We find that bromine and iodine concentrations and Br enrichment (relative to sea salt content) in polar ice do vary seasonally in Arctic snow and Antarctic ice. Although seasonal vari- ability in halogen emission sources is recorded by satellite- based observations of tropospheric halogen concentrations, seasonal patterns observed in snowpack are likely also in- fluenced by photolysis-driven processes. Peaks of bromine concentration and Br enrichment in Arctic snow and Antarc- tic ice occur in spring and summer, when sunlight is present. A secondary bromine peak, observed at the end of summer, is attributed to bromine deposition at the end of the polar day. Iodine concentrations are largest in winter Antarctic ice strata, contrary to contemporary observations of summer maxima in iodine emissions. These findings support previous observations of iodine peaks in winter snow strata attributed to the absence of sunlight-driven photolytic re-mobilisation of iodine from surface snow. Further investigation is required to confirm these proposed mechanisms explaining observa- tions of halogens in polar snow and ice, and to evaluate the extent to which halogens may be applied as sea ice proxies.
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| 6. |
- Schüpbach, S., et al.
(författare)
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Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.
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