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| Titel |
Representing icebergs in the iLOVECLIM model (version 1.0) – a sensitivity study |
| VerfasserIn |
M. Bugelmayer, D. M. Roche, H. Renssen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 7 ; Nr. 8, no. 7 (2015-07-17), S.2139-2151 |
| Datensatznummer |
250116457
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| Publikation (Nr.) |
 copernicus.org/gmd-8-2139-2015.pdf |
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| Zusammenfassung |
| Recent modelling studies have indicated that icebergs play an active role in
the climate system as they interact with the ocean and the atmosphere. The
icebergs' impact is due to their slowly released meltwater, which freshens
and cools the ocean and consequently alters the ocean stratification and the
sea-ice conditions. The spatial distribution of the icebergs and their
meltwater depends on the atmospheric and oceanic forces acting on them as
well as on the initial icebergs' size. The studies conducted so far have in
common that the icebergs were moved by reconstructed or modelled forcing
fields and that the initial size distribution of the icebergs was prescribed
according to present-day observations. To study the sensitivity of the
modelled iceberg distribution to initial and boundary conditions, we
performed 15 sensitivity experiments using the iLOVECLIM climate model that
includes actively coupled ice sheet and iceberg modules, to analyse (1) the
impact of the atmospheric and oceanic forces on the iceberg transport, mass
and melt flux distribution, and (2) the effect of the initial iceberg size on
the resulting Northern Hemisphere climate including the Greenland ice sheet,
due to feedback mechanisms such as altered atmospheric temperatures, under
different climate conditions (pre-industrial, high/low radiative forcing).
Our results show that, under equilibrated pre-industrial conditions, the
oceanic currents cause the icebergs to stay close to the Greenland and North
American coast, whereas the atmospheric forcing quickly distributes them
further away from their calving site. Icebergs remaining close to Greenland
last up to 2 years longer as they reside in generally cooler waters.
Moreover, we find that local variations in the spatial distribution due to
different iceberg sizes do not result in different climate states and
Greenland ice sheet volume, independent of the prevailing climate conditions
(pre-industrial, warming or cooling climate). Therefore, we conclude that
local differences in the distribution of their melt flux do not alter the
prevailing Northern Hemisphere climate and ice sheet under equilibrated
conditions and continuous supply of icebergs. Furthermore, our results
suggest that the applied radiative forcing scenarios have a stronger impact
on climate than the initial size distribution of the icebergs. |
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