Poleward Expansion of the Hadley Circulation in CMIP5 Simulations

• Published in: Advances in atmospheric sciences 2013-05, Vol.30 (3), p.790-795
• Main Author: 胡永云 陶利军 刘骥平
• Format: Article
• Language: English
• Subjects: Air pollution; Anthropogenic factors; Atmospheric circulation; Atmospheric models; Atmospheric Sciences; Climate; Computer simulation; Earth and Environmental Science; Earth Sciences; Geophysics/Geodesy; Global warming; Greenhouse effect; Greenhouse gases; Hadley circulation; Hadley环流; Meteorology; Radiative forcing; Simulation; Widening; 南北向; 历史模拟; 模拟产生; 温室气体排放; 耦合模式; 观测分析; 辐射强迫
• ISSN: 0256-1530; 1861-9533
• DOI: 10.1007/s00376-012-2187-4

Observational analyses have demonstrated that the Hadley circulation has expanded poleward in recent decades. Important issues are what caused the widening of the Hadley circulation and whether the observed widening is related to anthropogenic forcing. In the present study, we use currently available simulations of the Coupled Model Intercomparison Project Phase-5 （CMIP5） to analyze changes in the width of the Hadley circulation. It is found that CMIP5 historical simulations with greenhouse gas （GHG） forcing generate a total widening of ,-0.15°±0.06°in latitude （10 yr）-1 for the period 1979-2005, and the widening in CMIP5 historical simulations with all forcings is -0.17°± 0.06° per decade. Similar to that in CMIP3, the simulated poleward expansion in CMIP5 is much weaker than the observational reanalyses. In CMIP5 projection simulations for the 21st century, magnitudes of widening of the Hadley circulation increase with radiative forcing. For the extreme projected radiative forcing of RCP8.5, the total annual-mean widening of the Hadley circulation is -0.27°±0.04° （10 yr）-1 in the 21st century. Although CMIP5 underestimates observed poleward expansion of the Hadley circulation, the results of this study suggest that the observed trends in the width of the Hadley circulation are caused by anthropogenic forcing and that increasing GHGs play an important role in the observed poleward expansion of the Hadley circulation, in addition to other foreings emphasized in previous studies.