The Relationship between the El Ni(n)o/La Ni(n)a Cycle and the Transition Chains of Four Atmospheric Oscillations.Part Ⅱ: The Relationship and a New Approach to the Prediction of El Ni(n)o

摘要

The authors explored the connection and transition chains of the Northern Oscillation(NO) and the North Pacific Oscillation(NPO), the Southern Oscillation(SO), and the Antarctic Oscillation(AAO) on the interannual timescale in a companion paper. In this study, the connection between the transition chains of the four oscillations(the NO and NPO, the SO and AAO)and the El Nio/La Nia cycle were examined. It was found that during the transitions of the four oscillations, alternate anticyclonic/cyclonic correlation centers propagated from the Western Pacific to the Eastern Pacific along both sides of the equator. Between the anticyclonic/cyclonic correlation centers, the zonal wind anomalies also moved eastwardly, favoring the advection of sea surface temperature anomalies from the tropical Western Pacific to the Eastern Pacific. When the anticyclonic anomalies arrived in the Eastern Pacific, the positive phase of NO/SO and La Nia were established and vice versa.Thus, in 4-6 years, with an entire transition chain of the four oscillations, an El Nio/La Nia cycle completed. The eastward propagation of the covarying anomalies of the sea level pressure, zonal wind, and sea surface temperature was critical to the transition chains of the four oscillations and the cycle of El Nio/La Nia.Based on their close link, a new empirical prediction method of the timing of El Nio by the transition chains of the four oscillations was proposed. The assessment provided confidence in the ability of the new method to supply information regarding the long-term variations of the ocean and atmosphere in the tropical Pacific.