15 Oct 2015

For a long time, people have been wondering what the term El Nino means. It has become synonymous with the weather bulletin across the world’s television and radio stations, especially during drought years.

The term refers to the large scale ocean atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the Central and East Central Equatorial Pacific.

El Nino means The Little Boy or Christ Child in Spanish. It is understood that El Nino was originally recognised by fishermen off the coast of South America in the 1600s by the appearance of unusually warm water in the Pacific Ocean.

The name was chosen based on the time of year, usually around December, when the warm water events tended to occur. 

El Nino is the warm phase of the El Nino Southern Oscillation (ENSO).

The presence of El Nino can significantly influence weather patterns, ocean conditions, and marine fisheries across large portions of the globe for an extended period of time. 

The current El Nino, which will last throughout summer, is considered one of the top four on record in terms of strength.

It has been balanced by another trend, the Indian Ocean dipole, in which warmer waters off Indonesia help bring moisture, and therefore rain, to the Southern Hemisphere.

Principal Meteorologist Mr Radithupa Radithupa says in an interview that El Nino is a phenomenon where the oceans get warm, particularly in the Pacific around Peru, South America. He says that the cooling down of the oceans is called La Nina or El Viejo, anti-El Nino, or simply "a cold event".

He noted that the warming up of the oceans in Peru is seen as a bad thing as it leads to decreased fish numbers.

He said that El Nino translates to ngwaga o motonayana (male year) in Setswana while La Nina is ngwaga o monamagadi (female year).

“There is a tele-connection, which is a certain phenomenon happening somewhere in the world and affecting the weather system elsewhere,” he said,

Mr Radithupa observes that an El Nino year usually has deficient or below normal rainfall in southern Africa and abundant or above normal rainfall in East Africa.

 “We have had El Nino since observations began. The biggest El Nino ever recorded was in 1997,” he says.

He reveals that instruments called buoys are thrown into the ocean to collect information on sea surface temperatures that is then transmitted to the satellite for observation.

He says while El Nino contributes about 30 percent to the southern African rainfall pattern, there are some locally contributing factors.

Mr Radithupa notes that the El Nino occurrence this year is not as big as that experienced in 1997. He says that it’s warmth is about 0.4 degrees anomaly or above average. He argues that El Nino has an indirect effect on the volume of rainfall.

On the other hand there is La Nina which means The Little Girl in Spanish. La Nina is also sometimes called El Viejo, anti-El Nino, or simply "a cold event."

La Nina impacts tend to contrast those of El Nino. In the tropics, ocean temperature variations in La Nina tend to contradict those of El Nino. Normally, El Nino occurs more frequently than La Nina. Ends