Rainfall extremes in some selected parts of Central and South America: ENSO and other relationships reexamined
✍ Scribed by Kane, R.P.
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 292 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0899-8418
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✦ Synopsis
El Nin ˜os and anti-El Nin ˜os (La Nin ˜as) are known to be associated with rainfall extremes in several parts of the globe. However, not all El Nin ˜os show good associations. Recently, a finer classification of El Nin ˜o events was attempted. It was noticed that Unambiguous ENSOW (El Nin ˜o -Southern Oscillation, Warm) events (years when El Nin ˜o existed, and the Tahiti minus Darwin pressure difference (T -D) minima and equatorial eastern Pacific sea surface temperature (SST) maxima occurred in the middle of the calendar year) were very well associated with droughts in India and southeast Australia (Tasmania). In addition, C (cold SST, La Nin ˜a) events showed reverse effects (excess rains) in these regions. In the present paper, rainfall in selected regions in Central and South America are examined. For the Southern Oscillation Core Region (low latitudes, 155°W -167°E) and for the Gulf -Mexico region, no finer classification was necessary. All El Nin ˜os were associated with excess rains and all La Nin ˜as with droughts. As in India and Tasmania, Unambiguous ENSOW years were associated with droughts in some parts of northeast Brazil (Ceara, Rio grande do Norte, Paraiba, Pernambuco) and excess rains in Chile and Peru. C events did not have good associations except in Chile and Peru, where droughts occurred. The effect of El Nin ˜os showed some dependence on the month of commencement. In years when El Nin ˜os showed no effect, considerable influence of other factors (e.g. Atlantic SST on northeast Brazil rainfall) was noticed. Thus, predictions based on El Nin ˜o alone are likely to be erroneous, a fact which should be noted by the mass media. Effects of the recent El Nin ˜o of 1997 -1998 are discussed.