Forced summer stationary waves: the opposing effects of direct radiative forcing and sea surface warming

Autor: Christopher H. O'Reilly, Hideo Shiogama, Tim Woollings, Cheikh Mbengue, Myles R. Allen, Hugh S. Baker, Sarah Sparrow
Rok vydání: 2019
Předmět:
Zdroj: Climate Dynamics. 53(7-8)
ISSN: 0930-7575
Popis: We investigate the opposing effects of direct radiative forcing and sea surface warming on the atmospheric circulation using a hierarchy of models. In large ensembles of three general circulation models, direct $$\hbox {CO}_2$$ forcing produces a wavenumber 5 stationary wave over the Northern Hemisphere in summer. Sea surface warming produces a similar wave, but with the opposite sign. The waves are also present in the Coupled Model Intercomparison Project phase 5 ensemble with opposite signs due to direct $$\hbox {CO}_2$$ and sea surface warming. Analyses of tropical precipitation changes and equivalent potential temperature changes and the results from a simple barotropic model show that the wave is forced from the tropics. Key forcing locations are the Western Atlantic, Eastern Atlantic and in the Indian Ocean just off the east coast of Africa. The stationary wave has a significant impact on regional temperature anomalies in the Northern Hemisphere summer, explaining some of the direct effect that $$\hbox {CO}_2$$ concentration has on temperature extremes. Ultimately, the climate sensitivity and future changes in the land–sea temperature contrast will dictate the balance between the opposing effects on regional changes in mean and extreme temperature and precipitation under climate change.
Databáze: OpenAIRE
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