Temporal variability in the withdrawal phase of southwest monsoon over India and related consequences in northeast monsoon: a climatological perspective.

The variability in duration of withdrawal phase of southwest monsoon over India is often witnessed to influence the northeast monsoon rainfall of India as withdrawal phase is confined between the cessation of southwest monsoon and onset of northeast monsoon. The influence of withdrawal process of southwest monsoon on the variability in southwest monsoon rainfall has been well discussed; however, its impact on the variability in northeast monsoon rainfall is yet to explore. The present investigation is carried out from 1986 to 2016 to identify the important changes associated with withdrawal phase of southwest monsoon and the related variability in northeast monsoon rainfall. Different withdrawal events from 1986 to 2016 is thus divided into three phases: long withdrawal phase (LWP) (> 40 days), medium withdrawal phase (MWP) (30–40 days) and short withdrawal phase (SWP) (20–30 days). It is observed from the study that factors responsible for the variable withdrawal phase of southwest monsoon shifts more towards south/southeast directions during SWP compared to LWP. LWP is accompanied with low rainfall activity along with short length of rainy season over southern peninsular India during the northeast monsoon. Conversely, a reverse result is observed in the case of SWP. The result further shows that LWP and SWP are associated with opposite discernible features during the north–south movement of the monsoon system; however, MWP acts as a mediator and may be considered as standard or normal withdrawal phase of southwest monsoon based on 30 years (1986–2016) climatology. Early/delayed withdrawal of southwest monsoon has no association with the duration of withdrawal phase. [ABSTRACT FROM AUTHOR]