Sun-Spots und El Nino

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Sun-Spots und El Nino

• Ulrich Cubasch
• Freie Universität Berlin

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GPRC
Xie Arkin
NCEP-reanalysis
The precipitation anomaly in the tropical
Pacific during solar maximum
van Loon et al, 2006
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argument chain (van Loon et al, 2006)

• more solar forcing
• stronger convergence zones
• more precipitation and stronger trade winds
• more upwelling of colder water in the Pacific
• La Nina

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inverse argument chain (Mendoza, 1991 Handler
Andsager, 1990, Adams et al, 2003)

• less solar forcing (solar min., vulcanoes)
• weaker convergence zones
• less precipitation in ITCZ and weaker trade winds
• less upwelling of colder water in the Pacific
• El Nino

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observed
The precipitation anomaly during solar maximum
van Loon et al, 2006
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Wenn ich den Sonnenfleckenzyklus kenne, kann ich
ENSO und den Regen in Kalifornien für 10 Jahre
vorhersagen!?
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..aberENSO hat keinen 11-Jahreszyklus!
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MTM-SVD
Eigenmodes in the tropical Pacific
White and Tourre, 2003
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Response of a delayed oscillator model to solar
forcing
White et al, 2003
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The 11-yr signal in Suns irradiance appears to
excite a damped resonant response (i.e., the QDO)
in the Earths climate system. The QDO is excited
by a quasi-decadal external signal, not by
internal noise or instability in the Earths
climate system.
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Possible Ways for Solar Influence on Climate
Sun
Sun
Visible
UV
nicht stark genug (Warren et al, 2003)
Ozone
T, U
Strat.
Strat.
trop.
trop.
Dynamical impact
Radiative impact
?
Earth
Earth
Direct Influence
Indirect Influence
modified from Kuni Kodera (2005)
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(No Transcript)
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Quasi-decadal changes in tropical global-average
upper ocean temperature are associated with
changes in the overlying troposphere and
stratosphere
(White, 2005)
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Mechanism Influence of the 11-Year Solar Cycle
Thermosphere
UV radiation
Mesosphere
Stratopause
Stratosphere
Circulation changes (wind, waves, meridional BD
circulation)
Tropopause
?
?

Troposphere
?
?
QDO, ENSO, QBO
modified from Matthes, 2006
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Summary

• The solar variability generates a ENSO like
  signal (with La Nina at solar maximum and El Nino
  at solar minimum).
• This ENSO like signal appears to be the QDO in
  the Pacific, which is phase locked with the solar
  cycle.
• The direct radiative heating anomaly is
  insufficient to explain the amplitude of the
  response.
• It is therefore likely that the anomalous heating
  of the stratosphere during solar maximum
  interacts with the ocean surface. The mechanisms
  are not yet clear.

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The Sun is the key to decadal forecasting.