Distinct synoptic patterns associated with pre-break onset phase and revival of normal monsoon phase

Abstract

In the present study, an attempt has been made to synoptically classify the intraseasonal variation of Indian summer monsoon into two new monsoon conditions except already existing active and break monsoon conditions. These are transitional phases found prior to occurrence of break monsoon (here after “Pre-break onset phase”) and during revival of normal monsoon after the culmination of break monsoon phase (here after “Revival of normal monsoon phase”) and they have distinct synoptic patterns differing from patterns that are associated with active/break monsoon conditions. The distinct circulation, rainfall and pressure distribution associated with pre-break onset and revival of normal monsoon phases are also discussed.
 The study shows that strong negative pressure anomaly and excess rainfall over north India and strong positive pressure anomaly and deficient rainfall over Peninsular India are associated with pre-break onset phase and vice-versa with revival of normal monsoon.