Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 7, 5229-5236, 2007
© Author(s) 2007. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
10 Oct 2007
Observed poleward expansion of the Hadley circulation since 1979
Y. Hu1 and Q. Fu2 1Dept. of Atmospheric Sciences, Peking University, Beijing, China
2Dept. of Atmospheric Sciences, University of Washington, Seattle, USA
Abstract. Using three meteorological reanalyses and three outgoing long-wave radiation (OLR) datasets, we show that the Hadley circulation has a significant expansion of about 2 to 4.5 degrees of latitude since 1979. The three reanalyses all indicate that the poleward expansion of the Hadley circulation in each hemisphere occurs during its summer and fall seasons. Results from the OLR datasets do not have such seasonality. The expansion of the Hadley circulation implies a poleward expansion of the band of subtropical subsidence, leading to enhanced mid-latitude tropospheric warming and poleward shifts of the subtropical dry zone. This would contribute to an increased frequency of midlatitude droughts in both hemispheres.

Citation: Hu, Y. and Fu, Q.: Observed poleward expansion of the Hadley circulation since 1979, Atmos. Chem. Phys., 7, 5229-5236,, 2007.
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