On the relationship between ENSO patterns and winter precipitation over North and Central India

Abstract

The inter-annual variability of seasonal precipitation over India strongly depends upon the El Nino-Southern Oscillation (ENSO) phenomenon. The ENSO is anti-correlated with Indian summer monsoon (ISM). While, the Indian north-east monsoon, and the north and central India winter precipitation (NCIWP) are correlated with ENSO. Previous studies have shown that the strength of the ISM–ENSO teleconnection is quite dependent on the zonal position of the El Nino warming. Similarly, in this study it has been found that, the NCIWP depends upon the warming of the eastern Pacific (EP) El Nino rather than the central Pacific (CP) El Nino. The EP El Nino warms the western Indian Ocean during the winter season which intensifies the Hadley cell with its subsidence over central India. The sinking motion over central India shifts and intensifies the sub-tropical westerly jet (SWJ) over northern India. The SWJ intensifies the frequent surges in mid-latitude, called western disturbances (WDs) which, results in excess precipitation over the north and central India. Also, the subsidence over central India leads to lower level cyclonic circulation over central Indian landmass, which converges winds from warm Arabian Sea to north India supplying with abundant moisture for the WDs.