The response of the Southern Hemispheric eddy-driven jet to future changes in shortwave radiation in CMIP5

• Published in: Geophysical research letters 2014-05, Vol.41 (9), p.3244-3250
• Main Authors: Ceppi, Paulo, Zelinka, Mark D., Hartmann, Dennis L.
• Format: Article
• Language: English
• Subjects: Climate models; cloud feedbacks; Clouds; Global warming; jet streams; Joining; Marine; Meteorology; Phase shift; radiative feedbacks; Sea ice; Sea surface temperature; shortwave radiation; Spreads
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2014GL060043

A strong relationship is found between changes in the meridional gradient of absorbed shortwave radiation (ASR) and Southern Hemispheric jet shifts in 21st century climate simulations of CMIP5 (Coupled Model Intercomparison Project phase 5) coupled models. The relationship is such that models with increases in the meridional ASR gradient around the southern midlatitudes, and therefore increases in midlatitude baroclinicity, tend to produce a larger poleward jet shift. The ASR changes are shown to be dominated by changes in cloud properties, with sea ice declines playing a secondary role. We demonstrate that the ASR changes are the cause, and not the result, of the intermodel differences in jet response by comparing coupled simulations with experiments in which sea surface temperature increases are prescribed. Our results highlight the importance of reducing the uncertainty in cloud feedbacks in order to constrain future circulation changes. Key Points Large intermodel spread in SW radiation response to global warming in CMIP5 Spread in SW changes causes spread in SH jet response to global warming Different SW changes cause different changes in midlatitude baroclinicity