Main features of the westward-moving low pressure systems which form over the Indian region during the summer monsoon season and their relation to the monsoon rainfall

Abstract

The main features of the transitory monsoon low pressure systems (LPS) over the Indian region during the period 1888-1983, in respect of their formation, life, movement, intensity and dissipation, as well as their Inter annual variability are examined by utilizing the Information and data contained In the Indian Daily Weather Reports. The relationships of these features with the monsoon rainfall over India/north India/central India/south India are examined.

The paper discusses a variety of statistics about the low pressure systems, e.g., formation, location, life, intensity, movement and dissipation.

The number of LPS formed is not significantly related to the monsoon rainfall over India except for a weak relationship with central India monsoon rainfall. Number of LPS days during the season is significantly and directly related to the Indian monsoon rainfall (abov.e.5%) and to central Indian monsoon rainfall (above I %) and these relationships generally show good stability. Total westward longitudinal displacement of the LPS during the season and the monsoon rainfall over India and central India are directly and significantly (above 1 %) related and these relationships also generally show good stability.