Twin of El Nino found in Indian Ocean - the two El Ninos seem to be linked - Brief Article

Science News, Dec 24, 1994

The devilish, weather-disrupting phenomenon known as El Nino is not an only child, report scientists who have discovered a sibling in the Indian Ocean.

The term El Nino (Spanish for "the child") refers to a pronounced warming that develops occasionally in the equatorial eastern Pacific and warps weather around the globe. South American fishermen coined the name because the warming typically reaches their western coastline around Christmastime. An El Nino begins when ocean warmth and thunderstorms normally found in the western Pacific spread eastward along the equator.

Yves M. Tourre of Columbia University's Lamont-Doherty Earth Observatory and Warren B. White of the Scripps Institution of Oceanography discovered that a similar type of warming occurs in the Indian Ocean at the same time an El Nino grips the Pacific. Tourre and White discerned the Indian Ocean pattern while studying records of sea surface and subsurface temperatures for the period 1979 to 1991.

The Indian El Nino starts when warming along East Africa moves along the equator to the center of the ocean. That shift happens in lockstep with the relocation of warmth from the western to eastern Pacific. Following the mature stage of an El Nino, the central Indian warmth moves southeast into the Timor Sea separating Australia from Indonesia.

Meteorologists in the past have noted that Pacific El Ninos can have long-distance effects, robbing moisture from India and even southern Africa, on the opposite side of the globe. The discovery of an Indian El Nino much closer to Africa could help explain such long-range connections, Tourre says.