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| Titel |
The Land-Sea Warming Contrast as the Driver of Tropical Sea Level Pressure Changes |
| VerfasserIn |
T. Bayr, D. Dommenget |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250059437
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| Zusammenfassung |
| In this presentation we address the causes of the large-scale tropical sea level pressure (SLP )
changes during climate change. The analysis we present is based on climate change model
simulations, observed trends and the seasonal cycle. In all three cases the regional changes of
tropospheric temperature (Ttropos) and SLP are strongly related to each other.
This relationship basically follows the Bjerknes Circulation Theorem, with relative
low regional SLP where we have relative high Ttropos and vice versa. A simple
physical model suggests a tropical SLP response to horizontally inhomogeneous
warming in the tropical Ttropos, with a regression coefficient of about -1.7 hPa/K. This
relationship explains a large fraction of observed and predicted changes in the tropical
SLP .
It is shown that in climate change model simulations the tropical land-sea warming contrast,
is the most significant structure in the regional Ttropos changes relative to the tropical mean
changes. Since the land-sea warming contrast exist in the absent of any atmospheric
circulation changes it can be argued that the large-scale response of tropical SLP changes is
to first order a response to the tropical land-sea warming contrast, with decreasing SLP over
the sector of strongest warming (South America to Africa) and increasing SLP elsewhere,
which is roughly the Indo-Pacific warm pool region. A model intercomparison reveals that
climate models with a strong land-sea contrast in surface temperature tend to have also a
strong land-sea contrast in Ttropos and SLP . In an idealized land-sea contrast experiment a
similar response of the SLP and Ttropos as in the climate change experiments can be found.
As SLP changes and changes in atmospheric circulation go hand in hand, these
results suggest an increase in the potential for deep convection conditions over the
Atlantic Sector and a decrease over the Indo-Pacific warm pool region in the future. |
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