Abstract

The áclassical chronology of El Niño events for the past four and a half centuries proposed by Quinn et al. (1987) was primarily based upon indications of anomalous meteorological and hydrological phenomena observed in Peru and neighboring areas, as described by various authors and anonymous sources. This sequence of reconstructed El Niño events, later improved and modified by Quinn (1992, 1993; Quinn and Neal 1992), became the major reference for proxy calibrations and for most studies on climate variability related to El Niño/Southern Oscillation (ENSO) during historical, pre-instrumental, times. Precisely because global and regional records of interannual climate variability are becoming more diversified and accurate, there is an urgent need to reevaluate and consolidate the documentary record of El Niño manifestations, particularly in southwestern South America, a key area for ENSO studies.

A preliminary revision of some of the sources used by Quinn et al. (1987) to elaborate on their record (Hocquenghem and Ortlieb 1992b) showed that some of the El Niño events were actually poorly documented and simply may not have occurred. For instance, some events had been reconstructed exclusively from evidence of Rímac River floods at Lima, while no clear relationship has been established between these floods and ENSO manifestations. Another question concerns the significance of anomalous rains in southern Peru: Do they correspond to El Niño situations, as inferred by Quinn et al., or rather to conditions associated with the opposite phase of the Southern Oscillation (La Niña)? Furthermore, a previous analysis of documentary sources on rainfall excess in central Chile during the sixteenth through nineteenth centuries (Ortlieb 1994) revealed many discrepancies with respect to the regional El Niño record of Quinn.