Results

The detailed results of these analyses are presented by Goldberg et al [6]. The data have shown that enhanced rainfall during El Niņo can be divided into two categories; first, a general increase in background levels over non-El Niņo periods and second, sporadic bursts of intense rainfall superimposed over the enhanced background levels (cf., Figure 3). It is these sporadic bursts which were most responsible for the great damage during the 1982-1983 El Niņo episode.

The data further show that the severe storms (or bursts) often originate near the Andean foothills and may be induced by the interaction of rainbands moving inland from the coast with mountain downslope winds. This is best shown with a time sequence during such an event. Figures 12 and 13 illustrate the distribution of rainfall for January 24-27, and May 19-22, 1983, respectively, when a severe series of storms took place. The gridding process described earlier is used to create a pseudo-colored mesh independently for each day. The mesh is deformed by the altitude at each node, which is determined from the same gridding process applied to the altitude of each station. This deformed surface gives a reasonable approximation of the topography in northwestern Peru, especially given the paucity of high-resolution elevation data for this region.

Figure 12. Rainfall Distributon in Northwestern Peru on January 24-27, 1983.

 


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Last modified on February 11, 1999, G. Scott Owen, owen@siggraph.org