Is the trend in TEJ reversing over the Indian subcontinent?

Abstract

Indian Summer Monsoon (ISM) is mainly characterized by seasonal wind reversal in low level jet stream and tropical easterly jet (TEJ) among several other elements of monsoon systems. TEJ is observed in general between 100 and 150 hPa during June-September over the Indian region and its strength is directly related to the monsoon rainfall. In the context of changing climate, large reduction in its extent and weakening of its strength were reported. Using high resolution measurements, we report here the observation of a sharp strengthening of the TEJ during the recent warmest decade (2001-2010), reaching its 1970s value. We also show that this change is reflected in the tropical cyclone systems and finally on the precipitation patterns over the Indian region as they are interlinked. We attribute this unusual change partly to the change in the circulation due to the tropospheric warming and lower stratospheric ozone recovery. Key Points Showed that Indian Summer Monsoon circulation has changed in recent past Its effect on number of cyclones over Bay of Bengal is also going to change ISM modelers/forecasters need to consider these issues in future modeling ©2013. American Geophysical Union. All Rights Reserved.