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El Niņo translates from Spanish as 'the boy-child'. Peruvian fisherman originally
used the term - a reference to the Christ child - to describe the appearance,
around Christmas, of a warm ocean current off the South American coast.
Nowadays, the term El Niņo refers to the extensive warming of the central and
eastern Pacific that leads to a major shift in weather patterns across the Pacific.
In Australia (particularly eastern Australia), El Niņo events are associated
with an increased probability of drier conditions.
Changes to the atmosphere and ocean circulation during El Niņo events include:
- Warmer than normal ocean temperatures across the central and eastern tropical
Pacific Ocean.
- Increased convection or cloudiness in the central tropical Pacific Ocean - the
focus of convection migrates from the Australian/Indonesian region eastward
towards the central tropical Pacific Ocean.
- Weaker than normal (easterly) trade winds.
- Low (negative) values of the SOI (Southern Oscillation Index).
Monitoring these changes help to detect an El Niņo event and forecast its lifetime. |
