Cooling trend in the upper troposphere and lower stratosphere over China

Abstract

A strong cooling trend (-0.62°C per decade) in the upper troposphere and lower stratosphere (UTLS) over China is detected based on the records of 109 radiosonde stations during the period from 1980 to 2004. In contrast the underlying mid and lower troposphere (MLT) exhibits a relatively weak warming trend (0.17°C per decade) with the largest magnitude at the surface. Accompanying these changes in air temperature, large-scale circulation associated with the monsoon activity in East Asia declines remarkably in both winter and summer. Meanwhile, decreasing trend of the total ozone amount has also been found in the same period. Numerical simulations using two global coupled climate models further suggest that the ozone depletion and enhanced anthropogenic greenhouse effect play an important role in the cooling of UTLS and warming of MLT. Copyright 2007 by the American Geophysical Union.