Observed poleward expansion of the Hadley circulation since 1979

[摘要] Using three meteorological reanalyses and three outgoing long-wave radiation(OLR) datasets, we show that the Hadley circulation has a significantexpansion of about 2 to 4.5 degrees of latitude since 1979. The threereanalyses all indicate that the poleward expansion of the Hadleycirculation in each hemisphere occurs during its summer and fall seasons.Results from the OLR datasets do not have such seasonality. The expansion ofthe Hadley circulation implies a poleward expansion of the band ofsubtropical subsidence, leading to enhanced mid-latitude troposphericwarming and poleward shifts of the subtropical dry zone. This wouldcontribute to an increased frequency of midlatitude droughts in bothhemispheres.

[学科分类] 大气科学