​The 'Kerala key': Tracing southwest monsoon patterns across India

The India Meteorological Department (IMD) has predicted that the annual southwest monsoon is likely to start its journey over Kerala on May 31, with a model error of four days, marking the beginning of the crucial four-month rainfall period that holds immense significance for India's agricultural economy.

The rainy season, also known as the southwest monsoon Season, commences in June and persists until September. During this period, the monsoon makes its presence felt as it progresses across the region. Winds originating from the Arabian Sea and Bay of Bengal move towards the land, carrying moisture along their path. As these moisture-laden winds encounter mountain barriers, they trigger the onset of rainfall.

In the preceding month, the IMD had projected above-normal rainfall for the June to September Southwest Monsoon season, with June and July being particularly pivotal months for agriculture, as this period constitutes the primary phase for sowing the kharif crop.

Mrutyunjay Mohapatra, the Director General of the IMD, affirmed that this anticipated onset date aligns closely with the normal arrival date for the monsoon over Kerala, which typically occurs around June 1, emphasising that this year's predicted onset is not considered early but rather near the normal date.

Two key factors were identified as contributing to the likelihood of abundant rainfall: firstly, a positive Indian Ocean Dipole (IOD), indicating cooler than usual temperatures in the eastern Indian Ocean compared to the western region, which facilitates rainfall across several southern Indian states; and secondly, a diminished snow cover in the northern hemisphere and Eurasia, with Mohapatra elucidating the historical "inverse relationship" between the extent of snow cover in these regions and the intensity of the monsoon.

The commencement date of the monsoon holds paramount importance in tracking its journey throughout the nation, as it offers respite from the intense summer heat while progressing towards the North, underscoring the significance of the IMD's forecast for the agricultural sector and the nation as a whole.

The Indian economy is heavily reliant on agriculture, with 70% of the population depending on it directly or indirectly, and 58% of total employment generated through this sector. Agriculture contributes around 18% to the country's GDP. The success of Kharif crops is contingent upon the performance of the Southwest monsoon, which brings more than 75% of India's annual rainfall from June to September. Crop failure and deficient rainfall often lead to mass farmer suicides, as a significant portion of the crop area lacks manual irrigation methods. A good monsoon boosts farm output and rural income, stimulating demand for consumer goods. Monsoon-friendly crops like sugarcane, jute, and paddy thrive in areas with abundant rainfall during summers, while wheat and barley, requiring moderate temperature and water, are cultivated in winters.