Comparative study of the Pacific ENSO event of 1991-92 and the Atlantic ENSO-like event of 1991

Abstract

Anomalous conditions in the tropical Pacific and Atlantic Oceans during the ENSO event of 1991-92 are examined, using mainly the daily sea surface temperature (SST) data of the Russian Hydrometeorological Centre from April 1991 to December 1992. The event was characterized by some unusual features. It began in (boreal) spring 1991 as a weak event, then the SST anomalies (SSTAs) intensified and exceeded those in the ENSO of 1986-87. The 1991-92 event was manifested first in the enhanced average annual SST in the central and western parts of the equatorial Pacific. Significant persistent SSTAs near the South American coast were absent in 1991, occurring only at the beginning of 1992. The amplitude of the SST annual harmonic increased in the eastern and central equatorial Pacific. However, it decreased in the western equatorial Pacific during ENSO relaxation. High-amplitude and relatively short-term variability in the air-ocean system also occurred during the ENSO of 1991-92. The Pacific ENSO was accompanied by an Atlantic ENSO-like event, which also began in (boreal) spring 1991. It was manifested in the reduced intensity of the trade wind, the anomalously southern location of the intertropical convergence zone, and warm SSTAs in the eastern equatorial Atlantic. The mature SSTAs in the equatorial Pacific lagged behind those occurring in the equatorial Atlantic during the ENSO of 1991-92.