 |
| Titel |
Dependence of Eemian Greenland temperature reconstructions on the ice sheet topography |
| VerfasserIn |
N. Merz, A. Born, C. C. Raible, H. Fischer, T. F. Stocker |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1814-9324
|
| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 3 ; Nr. 10, no. 3 (2014-06-25), S.1221-1238 |
| Datensatznummer |
250116988
|
| Publikation (Nr.) |
 copernicus.org/cp-10-1221-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| The influence of a reduced Greenland Ice Sheet (GrIS) on Greenland's surface
climate during the Eemian interglacial is studied using a set of simulations
with different GrIS realizations performed with a comprehensive climate
model. We find a distinct impact of changes in the GrIS topography on
Greenland's surface air temperatures (SAT) even when correcting for changes
in surface elevation, which influences SAT through the lapse rate effect. The
resulting lapse-rate-corrected SAT anomalies are thermodynamically driven by
changes in the local surface energy balance rather than dynamically caused
through anomalous advection of warm/cold air masses. The large-scale
circulation is indeed very stable among all sensitivity experiments and the
Northern Hemisphere (NH) flow pattern does not depend on Greenland's topography in the Eemian. In
contrast, Greenland's surface energy balance is clearly influenced by changes
in the GrIS topography and this impact is seasonally diverse. In winter, the
variable reacting strongest to changes in the topography is the sensible heat
flux (SHF). The reason is its dependence on surface winds, which themselves
are controlled to a large extent by the shape of the GrIS. Hence, regions
where a receding GrIS causes higher surface wind velocities also experience
anomalous warming through SHF. Vice-versa, regions that become flat and
ice-free are characterized by low wind speeds, low SHF, and anomalous low
winter temperatures. In summer, we find surface warming induced by a decrease
in surface albedo in deglaciated areas and regions which experience surface
melting. The Eemian temperature records derived from Greenland proxies, thus,
likely include a temperature signal arising from changes in the GrIS
topography. For the Eemian ice found in the NEEM core, our model suggests
that up to 3.1 °C of the annual mean Eemian warming can be
attributed to these topography-related processes and hence is not necessarily
linked to large-scale climate variations. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|