Correspondence between the large volcanic eruptions and ENSO events over AD 1525–2000

Abstract

ENSO is an interannual mode which may be affected by external forcing, such as volcanic eruptions. Based on the reconstructed volcanic eruptions chronology and ENSO sequences, both 195 large volcanic eruptions (VEI≥4) and 398 ENSO (El Niño and La Niña) events were extracted from 1525 to 2000. An analysis of the correspondence between the large volcanic eruptions and ENSO events was performed by matching the large volcanic eruptions with the types and magnitudes of ENSO events present in the 0–2 years after the eruptions. The results show the following: (1) The percentages of ENSO events within the 3 years after the large eruptions had increased to 68.3% from 31.7% compared with those with no-eruptions in the previous 0–2 years. In addition, the ratio of El Niño to La Niña events turned from 2:3 to 1:1, and more El Niño events occurred in the 0 year after eruptions in the low-latitudes of the Northern Hemisphere and in the tropics but more La Niña events occurred in the 0 year after in the high-latitudes of the Northern Hemisphere and the Southern Hemisphere. (2) After the eruptions, the weak (W) El Niño events had increased by 8 percentage points and the very strong (VS) El Niño events had decreased by 10 percentage points; conversely, there was a decrease by 15 percentage points of the weak La Niña events and an increase by 11.4 percentage points of the very strong La Niña events. Specifically, the percentages of strong La Niña events increased to a peak at 1 (+1) year after the eruptions. (3) The percentage of eruptions followed by single-year ENSO was the greatest. The percentage of ENSO events that occurred in the consecutive 2 years following an eruption was approximately equal to the percentage of events that occurred consecutively 3 years following an eruption, and both sets of ENSO magnitudes showed a decreasing trend.