ENSO-Related Precipitation Changes in New Caledonia, Southwestern Tropical Pacific: 1969–98

Abstract

An analysis of El Niño?Southern Oscillation (ENSO) related precipitation changes in New Caledonia, southwestern tropical Pacific, based on 21 selected stations covering the 1969?98 period is performed. The analysis at the ENSO timescale is complemented by an investigation of basin-scale precipitation changes in order to set the context, by an examination of changes in the flow rates of two major rivers of the island, and by a comparison between actual precipitation (P) records and the output of a simple linear regression model. The results indicate that a 20%?50% decrease in precipitation generally occurs during El Niño events, and vice versa during La Niña events. In accord with these P changes, the flow rates of the two rivers can almost double during La Niña years, and decrease by more that 50% during El Niño years. The magnitudes of the precipitation anomalies are however not strictly proportional to the strength of ENSO. Hence, it is found that the simple linear regression model based on the Southern Oscillation index can be used to infer the timing, but not the magnitude, of P changes.