Possible connection between El Nino/La Nina on Tropical Easterly Jetstream during Asian Summer Monsoon

The influence of El Nino/La Nina on the upper tropospheric circulation pattern over the Asian summer monsoon region has been studied using ERA interim reanalysis data for a period of 34 years (1980-2013). Tropical easterly jetstream (TEJ) shows considerable changes during the El Nino and La Nina events. The intensity of TEJ enhances and it spreads horizontally and vertically during La Nina years, whereas it weakens and shrinks spatially in El Nino years. The enhancement of upper tropospheric zonal wind during the La Nina events seems to alter the lower stratospheric circulation, thereby modulating the physics and dynamics of the upper troposphere and lower stratosphere (UT/LS) over the monsoon region.