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| Titel |
Is the climate sensitive to mean ocean salinity? |
| VerfasserIn |
Paul Williams, Eric Guilyardi, Gurvan Madec, Silvio Gualdi, Enrico Scoccimarro |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250031946
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| Zusammenfassung |
| On geological timescales, the mean salinity of the world ocean has varied widely. For
example, the global-mean salinity during the early Palaeozoic era is believed to
have exceeded 50Â psu. In principle, such high mean salinities could have profound
consequences for the climate, perhaps via impacts on the ocean’s thermohaline
circulation.
Motivated by the above possibility, we perform numerical simulations designed to elucidate
the role of mean ocean salinity in climate. Using a coupled atmosphere-ocean general
circulation model, we study a 100-year sensitivity experiment in which the global-mean
salinity is approximately doubled from its present observed value, by adding 35Â psu
everywhere in the ocean.
The salinity increase produces a rapid global-mean sea-surface warming of 0.8-C within a
few years, caused by reduced vertical mixing associated with changes in cabbeling. The
warming is followed by a gradual global-mean sea-surface cooling of 0.4-C within a few
decades, caused by an increase in the vertical (downward) component of the isopycnal
diffusive heat flux.
Perhaps surprisingly, we find no evidence of impacts on the variability of the thermohaline
circulation (THC) or El Niño/Southern Oscillation (ENSO). The mean strength of the
Atlantic meridional overturning is reduced by 20% and the North Atlantic Deep Water
penetrates less deeply. Nevertheless, our results dispute claims that higher salinities for the
world ocean have profound consequences for the thermohaline circulation. We find,
in fact, that the simulated climate is surprisingly insensitive to the global-mean
salinity.
Reference
Williams, PD, EÂ Guilyardi, GÂ Madec, SÂ Gualdi and EÂ Scoccimarro (2010) The role of
mean ocean salinity in climate. Dynamics of Atmospheres and Oceans, in press.
doi:10.1016/j.dynatmoce.2009.02.001 |
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