Climatic and oceanographic cycle affecting Southeast Asia, Australia and Africa
Water temperatures around the Mentawai Islands dropped about 4 °C during the height of a positive phase of the Indian Ocean Dipole in November 1997. During these events unusually strong winds from the east push warm surface water towards Africa, allowing cold water to upwell along the Sumatran coast. In this image blue areas are cooler than normal, while red areas are warmer than normal.
The Indian Ocean Dipole (IOD), also known as the Indian Niño, is an irregular oscillation of sea surface temperatures in which the western Indian Ocean becomes alternately warmer (positive phase) and then colder (negative phase) than the eastern part of the ocean.
