 |
| Titel |
Using data assimilation to investigate the causes of Southern Hemisphere high latitude cooling from 10 to 8 ka BP |
| VerfasserIn |
P. Mathiot, H. Goosse, X. Crosta, B. Stenni, M. Braida, H. Renssen, C. J. Meerbeeck, V. Masson-Delmotte, A. Mairesse, S. Dubinkina |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1814-9324
|
| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 2 ; Nr. 9, no. 2 (2013-04-03), S.887-901 |
| Datensatznummer |
250018026
|
| Publikation (Nr.) |
 copernicus.org/cp-9-887-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| From 10 to 8 ka BP (thousand years before present), paleoclimate records show an atmospheric and oceanic
cooling in the high latitudes of the Southern Hemisphere. During this
interval, temperatures estimated from proxy data decrease by
0.8 °C over Antarctica and 1.2 °C over the Southern
Ocean. In order to study the causes of this cooling, simulations covering
the early Holocene have been performed with the climate model of
intermediate complexity LOVECLIM constrained to follow the signal recorded
in climate proxies using a data assimilation method based on a particle
filtering approach. The selected proxies represent oceanic and atmospheric surface
temperature in the Southern Hemisphere derived from terrestrial, marine and
glaciological records. Two mechanisms previously suggested to explain the
10–8 ka BP cooling pattern are investigated using the data assimilation
approach in our model. The first hypothesis is a change in atmospheric
circulation, and the second one is a cooling of the sea surface temperature
in the Southern Ocean, driven in our experimental setup by the impact of an
increased West Antarctic melting rate on ocean circulation. For the
atmosphere hypothesis, the climate state obtained by data assimilation
produces a modification of the meridional atmospheric circulation leading to
a 0.5 °C Antarctic cooling from 10 to 8 ka BP compared to the
simulation without data assimilation, without congruent cooling of the
atmospheric and sea surface temperature in the Southern Ocean. For the ocean
hypothesis, the increased West Antarctic freshwater flux constrainted by
data assimilation (+100 mSv from 10 to 8 ka BP) leads to an oceanic
cooling of 0.7 °C and a strengthening of Southern Hemisphere
westerlies (+6%). Thus, according to our experiments, the observed
cooling in Antarctic and the Southern Ocean proxy records can only be
reconciled with the reconstructions by the combination of a modified
atmospheric circulation and an enhanced freshwater flux. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|