THE STRANGE INDIAN OCEAN event causing heavy rains in Kenya
Story by John Muchangi, visualizations by Lucy Swan
As a young post-doc fellow at a university in Japan, in 1998, Saji Hameed was puzzled by strange events that had taken place four years earlier. The 1994 summer (June-September) had been unusually hot in Japan, and researchers were still unable to identify the cause. Later that year, an Indian Ocean surface current that moves from west to east had reversed and moved in the opposite direction.
Saji and his colleagues finally unravelled the mystery in 1999. They discovered the events were triggered by unique air-sea interactions in the Indian Ocean, causing the ocean’s surface to cycle between cold and warm. They called the phenomenon the Indian Ocean Dipole (IOD). The cycle rotates around positive, negative and neutral. The extremely dry weather in Japan was caused by a positive IOD, which, on the other hand, dumps unusually heavy rains on East Africa.