 |
| Titel |
Southern Hemisphere Westerly Wind Changes during the Last Glacial Maximum: Model-Data Comparison |
| VerfasserIn |
Louise Sime, Karen Kohfeld, Corinne Le Quéré, Eric Wolff, Agatha De Boer, Robert Graham, Laurent Bopp |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080383
|
|
|
|
|
|
| Zusammenfassung |
| The Southern Hemisphere (SH) westerly winds are thought to be critical to both past and
future global ocean circulation, productivity, and carbon storage. For example, an
equatorward shift in the winds has been suggested as the leading cause for the reduction in
atmospheric CO2 during the Last Glacial Maximum (LGM), through its affect on the
Southern Ocean circulation. Despite the importance of the SH westerlies, paleo-records and
modelling studies still disagree on how they behaved during the LGM. Here, a
joint model-data evaluation study is performed to determine likely changes in the
SH westerly winds during the LGM. HadAM3 atmospheric simulations, along
with published PMIP2 coupled climate model simulations, are assessed against
our newly synthesised database of moisture records for the LGM (Kohfeld et al.,
accepted, QSR). While moisture data are the most commonly cited evidence in
support of a large equatorward shift in the SH winds during the LGM, none of the
models that produce realistic LGM precipitation patterns show a large equatorward
shift. In fact, the model which best simulates the moisture proxy data, our HadAM3
LGM simulation, shows a small poleward wind shift. Thus, moisture proxies do not
provide a robust observational evidence base for equatorward shifted winds during
the LGM (Sime et al, in press, QSR). Sensitivity simulations, featuring individual
boundary condition changes, suggest that changes in sea surface temperatures are the
strongest factor behind LGM wind changes, compared with sea ice and land ice
effects. If the SH westerly winds were not shifted equatorward at the LGM, this
raises intriguing questions regarding past and future carbon storage in the Southern
Ocean. |
|
|
|
|
|
|