Table 2 is simplified by only listing values for stations where the correlation magnitude exceeds 0.5. Shading is employed in the table to draw attention to the strongest relationships. From this table one can identify three Andean subregions with different climatic characteristics. The correlation coefficients between the precipitation indices in the Andean region and the SST anomaly indices for El Niño region 1+2 are moderately positive (the precipitation tends to be greater than the average during El Niño) in the north end of the northern subregion during November-March. The correlation coefficients are neutral in the central subregion, but moderately positive in November, and are slightly negative (the precipitation tends to be smaller than average during El Niños) in the southern subregion, but moderately negative in February.
The correlation coefficients between the precipitation indices in the Andeas and the SST anomaly indices for El Niño region 3.4 are weakly positive in the northern subregion, neutral in the central subregion and moderately negative in the southern subregion, particularly in February. The correlation coefficients between the precipitation indices and the SST anomaly indices for El Niño 4 region are very small in the north and moderately negative in the central and south subregions, particularly in February.
The correlation analysis indicates that precipitation in the northern coast is strongly related to the SST anomaly indices for El Niño region 1+2, mainly in the period January-March. During El Niño events, as defined by SCOR, the relationship intensifies, confirming the results of previous studies (Woodman, 1999, [and numerous others]). The correlation coefficients between the precipitation indices in the Peruvian Amazon region and the SST anomaly indices for the four El Niño regions are small in magnitude.