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| Titel |
The Arctic Summer Cloud Ocean Study (ASCOS): overview and experimental design |
| VerfasserIn |
M. Tjernström, C. Leck, C. E. Birch, J. W. Bottenheim, B. J. Brooks, I. M. Brooks, L. Bäcklin, R. Y.-W. Chang, G. de Leeuw, L. Di Liberto, S. de la Rosa, E. Granath, M. Graus, A. Hansel, J. Heintzenberg, A. Held, A. Hind, P. Johnston, J. Knulst, M. Martin, P. A. Matrai, T. Mauritsen, M. Müller, S. J. Norris, M. V. Orellana, D. A. Orsini, J. Paatero, P. O. G. Persson, Q. Gao, C. Rauschenberg, Z. Ristovski, J. Sedlar, M. D. Shupe, B. Sierau, A. Sirevaag, S. Sjogren, O. Stetzer, E. Swietlicki, M. Szczodrak, P. Vaattovaara, N. Wahlberg, M. Westberg, C. R. Wheeler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 6 ; Nr. 14, no. 6 (2014-03-19), S.2823-2869 |
| Datensatznummer |
250118515
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| Publikation (Nr.) |
 copernicus.org/acp-14-2823-2014.pdf |
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| Zusammenfassung |
The climate in the Arctic is changing faster than anywhere else on earth.
Poorly understood feedback processes relating to Arctic clouds and
aerosol–cloud interactions contribute to a poor understanding of the present
changes in the Arctic climate system, and also to a large spread in
projections of future climate in the Arctic. The problem is exacerbated by
the paucity of research-quality observations in the central Arctic. Improved
formulations in climate models require such observations, which can only
come from measurements in situ in this difficult-to-reach region with logistically
demanding environmental conditions.
The Arctic Summer Cloud Ocean Study (ASCOS) was the most extensive central
Arctic Ocean expedition with an atmospheric focus during the International
Polar Year (IPY) 2007–2008. ASCOS focused on the study of the formation and
life cycle of low-level Arctic clouds. ASCOS departed from Longyearbyen on
Svalbard on 2 August and returned on 9 September 2008. In transit into and
out of the pack ice, four short research stations were undertaken in the
Fram Strait: two in open water and two in the marginal ice zone. After
traversing the pack ice northward, an ice camp was set up on 12 August at
87°21' N, 01°29' W and remained in operation through 1
September, drifting with the ice. During this time, extensive measurements
were taken of atmospheric gas and particle chemistry and physics, mesoscale
and boundary-layer meteorology, marine biology and chemistry, and upper
ocean physics.
ASCOS provides a unique interdisciplinary data set for development and
testing of new hypotheses on cloud processes, their interactions with the
sea ice and ocean and associated physical, chemical, and biological
processes and interactions. For example, the first-ever quantitative
observation of bubbles in Arctic leads, combined with the unique discovery
of marine organic material, polymer gels with an origin in the ocean, inside
cloud droplets suggests the possibility of primary marine organically derived
cloud condensation nuclei in Arctic stratocumulus clouds. Direct
observations of surface fluxes of aerosols could, however, not explain
observed variability in aerosol concentrations, and the balance between local
and remote aerosols sources remains open. Lack of cloud condensation nuclei (CCN) was at times a
controlling factor in low-level cloud formation, and hence for the impact of
clouds on the surface energy budget. ASCOS provided detailed measurements of
the surface energy balance from late summer melt into the initial autumn
freeze-up, and documented the effects of clouds and storms on the surface
energy balance during this transition. In addition to such process-level
studies, the unique, independent ASCOS data set can and is being used for
validation of satellite retrievals, operational models, and reanalysis data
sets. |
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