Interannual variability of Indian winter monsoon over the Western Himalayas

Abstract

The Indian subcontinent is surrounded by mighty Himalayas in the north. It is characterized by heterogeneous topography and variable landuse from northwest to northeast. Apart from these, due to seasonal changes western, central and eastern Himalayas are having different precipitation patterns. In the present study Indian winter (December, January, February — DJF) monsoon (IWM) precipitation over the Western Himalayas (WH) is analyzed. During IWM, the WH receives almost one third of annual precipitation due to eastward moving cyclonic storms, western disturbances (WDs). Wet and dry precipitation years' composite analysis shows anomalous cyclonic flow over and across the northern India with higher clouding associated with precipitation over the Himalayan region during wet year. Significant southward shift of 200 hPa subtropical westerly jet (SWJ) with stationary wave pattern over south Asian region is seen during wet years. Over equatorial Pacific increased response of attenuated Walker circulation during El Niño situations is associated with higher precipitation wet years. Also, strengthening of Hadley circulation response within 30°S to 30°N provides symmetrical upper tropospheric meridional transport from Southern Hemisphere to Northern Hemisphere during wet years. Significant precursor dependency on evolution of sea surface temperature warming over equatorial eastern Pacific and cooling over western equatorial Pacific is seen.