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| Titel |
Modeling the 11-year Solar Signal in the Troposphere |
| VerfasserIn |
Anne Kubin, Janna Abalichin, Kleareti Tourpali, Ulrike Langematz, Patrick Jöckel |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051291
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| Zusammenfassung |
| There is observational evidence for an 11-year solar cycle influence on
tropospheric circulation and temperature. Simulations with chemistry
climate models (CCM) provide the opportunity to study the downward
transfer of the initial solar signal in the upper stratosphere to the
troposphere and to identify the processes that lead to the
observed changes in the troposphere.
We present results from a CCMVal Reference B1 simulation with the
EMAC-FUB CCM forced with observed sea surface temperatures and sea ice,
observed abundances of greenhouse gases and ozone depleting substances
and three major volcanic eruptions. The QBO in this simulation with the
resolution T42L39MA was assimilated. The intention with this experiment is
to simulate the period 1960 to 2005 as realistically as possible. A
multiple linear regression method is applied to analyse the model output.
We find that the 11-year solar signal in the troposphere in EMAC-FUB is most
prominent in late northern and southern winter. Under solar maximum
conditions there are positive annular mode-like anomalies in the
geopotential height field in the mid-troposphere in February with
consistent near-surface temperature changes. Changes in the propagation of
planetary waves are found to contribute to the solar signal. Since a
positive annular mode implies a more zonally directed flow it is analysed
whether the occurrence frequency of blockings is reduced during phases of
high solar activity. In July and August there is a solar influence on the
Indian monsoon circulation with stronger than average upward motion over
the Arabian peninsula at solar maximum. Simultaneously, the upwelling in
the Hadley circulation is weakened. |
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