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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L06805, doi:10.1029/2006GL028443, 2007

Expansion of the Hadley cell under global warming

Jian Lu

Climate and Global Dynamics Division, National Center for Atmospheric Research, University Corporation for Atmospheric Research, Boulder, Colorado, USA
University Corporation for Atmospheric Research Visiting Scientist Program, Geophysical Fluid Dynamics Laboratory, NOAA, Princeton University, Princeton, New Jersey, USA


Gabriel A. Vecchi

Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, Princeton University, Princeton, New Jersey, USA


Thomas Reichler

Department of Meteorology, University of Utah, Salt Lake City, Utah, USA


Abstract

A consistent weakening and poleward expansion of the Hadley circulation is diagnosed in the climate change simulations of the IPCC AR4 project. Associated with this widening is a poleward expansion of the subtropical dry zone. Simple scaling analysis supports the notion that the poleward extent of the Hadley cell is set by the location where the thermally driven jet first becomes baroclinically unstable. The expansion of the Hadley cell is caused by an increase in the subtropical static stability, which pushes poleward the baroclinic instability zone and hence the outer boundary of the Hadley cell.

Received 11 October 2006; accepted 21 February 2007; published 24 March 2007.

Keywords: Hadley cell; subtropical dry zone; static stability.

Index Terms: 0399 Atmospheric Composition and Structure: General or miscellaneous; 1806 Hydrology: Chemistry of fresh water; 1812 Hydrology: Drought.

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Citation: Lu, J., G. A. Vecchi, and T. Reichler (2007), Expansion of the Hadley cell under global warming, Geophys. Res. Lett., 34, L06805, doi:10.1029/2006GL028443.