Scientists are preparing to release robots into the Bay of Bengal in a study aimed at improving predictions of the region's monsoon rains.

The seasonal monsoon, which hits the region between June and September, delivers some 70% of India's surface water.

Its arrival is eagerly awaited by hundreds of millions of subsistence farmers across the country, and delays can ruin crops or exacerbate drought.

Yet the rains are hard to predict, and depend on a complex interplay between global atmospheric and oceanic movements that is not yet fully understood.

Scientists from the University of East Anglia said on Tuesday that the underwater robots being released from a ship into the Bay of Bengal later this month would be monitoring ocean temperatures and currents.