Monsoons and Ocean-Atmosphere Oscillations

The South Asian monsoon is one of the most consequential seasonal wind reversals on Earth, driven fundamentally by the differential heating of the Indian subcontinent and the Tibetan Plateau relative to the surrounding Indian Ocean. As the landmass heats intensely through the northern spring, it develops a strong area of low pressure that draws moisture-laden southwesterly winds inland from the ocean, producing the summer monsoon, roughly from June to September, which delivers an estimated 70-80% of India's annual rainfall in a single concentrated season. The monsoon's progress is closely tracked from its onset over the Kerala coast northward across the subcontinent, and its strength and timing are critical to agriculture, water supply, and the broader economy across South Asia; as the subcontinent cools in autumn, the flow reverses into a drier northeasterly winter monsoon.