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| Titel |
Landscape-precipitation feedback mediated by ice nuclei: an example from the
Arctic |
| VerfasserIn |
Emiliano Stopelli, Franz Conen, Lukas Zimmermann, Cindy Morris, Christine Alewell |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124392
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| Publikation (Nr.) |
 EGU/EGU2016-3820.pdf |
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| Zusammenfassung |
| The Arctic is one of the regions on Earth which are particularly sensitive to the effects of
climate change. One of the largest uncertainties in describing climate and climate change is
constituted by the characterisation of the behaviour of clouds. Specifically in the Arctic
region there is a low abundance of cloud condensation nuclei (CCN) resulting in low droplet
concentrations in clouds. Ice nucleating particles (INPs) in the atmosphere promote the
aggregation of water molecules into ice, increasing the chance for precipitation. Therefore, a
change in the absolute abundance of INPs and their relative presence compared to CCN is
expected to have strong impacts on climate in the Arctic in terms of the radiative budget and
of precipitation.
In July 2015 we sampled particles from air at Haldde Observatory, Norway (69˚ 55’45”
N, 22˚ 48’30” E, 905 m a.s.l.) on PM10 filters. We determined the number of INPs active at
moderate supercooling temperatures (≥ -15 ˚ C, INPs−15) by immersion freezing. To
identify potential sources of airborne INPs we also collected samples of soil from a highland
and decaying leaf litter. Air masses passing over the land were enriched in INPs−15, with
concentrations twice to three times larger than those found in air masses directly coming from
the Barents Sea. Ice nucleation spectra suggest that it is mainly litter which accounts for this
enrichment in INPs−15.
This example helps elucidating the feedback linking landscapes and atmosphere mediated
by INPs in the frame of climate change. While the snow coverage is progressively reducing in
the Arctic, areas with decaying leaf litter and vegetation that are exposed to wind
and grazing are expected to increase, resulting into a larger abundance of INPs
in the local atmosphere. This increase in airborne INPs can promote a change in
the freezing of clouds, with impact on the lifetime and on the radiative properties
of clouds, and ultimately on the occurrence of precipitation in the Arctic region. |
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