1. 1 Sun-Spots und El Nino Ulrich Cubasch Freie Universität Berlin

2. 2 NCEP-reanalysis GPRC Xie & Arkin The precipitation anomaly in the tropical Pacific during solar maximum van Loon et al, 2006

3. 3 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

4. 4 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

5. 5 The precipitation anomaly during solar maximum observed van Loon et al, 2006

6. 6 Wenn ich den Sonnenfleckenzyklus kenne, kann ich ENSO und den Regen in Kalifornien für 10 Jahre vorhersagen!?

7. 7 …..aber ENSO hat keinen 11- Jahreszyklus!

8. 8 Eigenmodes in the tropical Pacific White and Tourre, 2003 MTM-SVD

9. 9 Response of a delayed oscillator model to solar forcing White et al, 2003

10. 10 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.

11. 11 modified from Kuni Kodera (2005) Sun UV Earth Ozone T, U Indirect Influence Dynamical impact trop. Strat. Visible Earth Direct Influence Radiative impact trop. Strat. Sun ? Possible Ways for Solar Influence on Climate nicht stark genug (Warren et al, 2003)

12. 12

13. 13 Quasi-decadal changes in tropical global-average upper ocean temperature are associated with changes in the overlying troposphere and stratosphere (White, 2005)

14. 14 Mechanism – Influence of the 11-Year Solar Cycle Change of meridional temperature gradient Circulation changes (wind, waves, meridional BD circulation) Direct influence on temperature Influence on ozone QBO SAO Indirect influence, difficult to measure ? ? ? Change of Hadley & Walker cell Change of Monsoon UV radiation Mesosphere Stratosphere Troposphere Tropopause Stratopause Ocean ? Thermosphere QDO, ENSO, QBO modified from Matthes, 2006 ?

15. 15 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.

16. 16 The Sun is the key to decadal forecasting….