The onset and advance of Indian summer monsoon in relation with the sea level pressure field

Abstract

The dates of onset of monsoon over Kerala and the advance of monsoon exhibit large interannual and intra seasonal variability. The genesis of Indian summer monsoon is considered to be in the southern hemisphere, over the Mascarene Island. The pressure gradient between the high pressure over Mascarene Island and low pressure over North West India is the fundamental physical cause of the monsoon, which acts as a driving force for the monsoon winds. Thus, the genesis of monsoon and its further advance is closely related to the sea level pressure field. With this backdrop, the variability of the onset and advance of the monsoon in terms of sea level pressure field is examined in this study.  The pentad sea level pressure field does show contrast for the years of early and late onset of monsoon over Kerala and also for the years of rapid and sluggish advance of monsoon.