Phase shift of the seasonal cycle in the Hadley circulation in recent decades

Abstract

A trend of phase shift in the seasonal cycle of the Hadley circulation is detected from the three reanalyses data. There is a strengthening trend of the North cell of Hadley circulation in March and April, and a strengthening trend of the South cell of Hadley circulation in September and October. The result indicates the properties of the boreal winter circulation tend to remain into boreal spring, and the boreal summer circulation into boreal autumn. Three major reanalyses show qualitatively the same tendency. The seasonal cycle in zonal averaged tropical precipitation and OLR, which are independent from the reanalyses, also shows a phase shift consistent with the Hadley circulation especially in September. Copyright 2006 by the American Geophysical Union.