23.11.2015: FB1-Seminar

11:00 h, Hörsaal, Düsternbrooker Weg 20

Abstract:

A physical understanding of the climate response to the solar cycle forcing may improve efforts for decadal prediction. We exploit the largest ensemble of coordinated historical simulations undertaken within the 5th phase of the Coupled Model Inter-Comparison Project (CMIP5) to detect simulated influences of the 11-yr solar cycle. A lead/lag multiple linear regression analysis identifies a multi-model mean (MMM) global mean surface warming of about 0.07 K lagging the solar cycle by one to two years on average. Solar signals in the troposphere show a similar time lag of one to two years and the strongest MMM warming is simulated in the tropics above 300 hPa. In the stratosphere, the strongest tropical mean warming of 0.7 K on average is simulated at the stratopause at lag 0, as expected by the radiation-ozone iteraction. A subset of models show a statistically significant surface warming that is characterized by an anomalous warming in the west equatorial Pacific Ocean and the Arctic, at one to two years after solar maximum. The Arctic warming is twice as strong as the global mean response and appears in winter months only. The modellled surface warming in the equatorial Pacific and Arctic is weak but qualitatively similar compared to solar signals in the HadCRUT4 dataset. I will be discussing how SolarMIP analysis of the CMIP5 simulations can be used to constraint solar cycle signatures in observations.

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