Role of Indian Ocean in Influencing the Rainfall of Central India

Abstract

The Indian summer monsoon as a major component of the global climate system has received renewed attention in recent years. There are many instances of years with floods (strong monsoon) or drought (weak monsoon) during which India as a whole receives excess or deficient seasonal rainfall, respectively. Monsoon variations, particularly if they are unanticipated, impart significant economic and social consequences. On the other hand, an accurate long-lead prediction of monsoon rainfall can improve planning to mitigate the adverse effects of the inter-annual variability of the monsoon. One such attempt is made in this research to establish empirical relationships between sea-surface temperature (SST) and summer monsoon rainfall over Central India. India is surrounded by Indian Ocean and the annual cycle of SST in the Indian Ocean is crucially important in the distribution of precipitation over the Indian subcontinent. The study identifies four pockets in the Indian Ocean which can be considered as precursors to summer monsoon rainfall. Correlation analysis with lags in months was carried out to establish association between the SST over these pockets and summer monsoon rainfall. The study revealed that the relationship between the two variables has undergone phase-change, and has oscillated between inverse and direct correlation values. Besides, the study also reveals the relationship between SST and monsoon rainfall for different meteorological subdivisions of Central India, which further broadens the scope for researchers to evaluate the impact of coupled land-ocean and air interactions for different micro-spatial units of India.