资源环境科技发展态势分析平台

The recent 2014-2016 period was marked by a failed El Nino favoring a subsequent extreme El Nino with dramatic worldwide impacts. Here this new type of major event so-called the delayed super El Nino is realistically captured by a simple dynamical model for the equatorial Pacific with emphasis on the role of state-dependent stochastic wind bursts. We analyze qualitative analogues for this event compared and contrasted with the 1997-1998 super El Nino in ensemble experiments based on the simple model. In agreement with recent studies, the timing and intensity of such an event is strongly controlled by atmospheric wind bursts, both easterly and westerly. In particular, the early stalling by easterly wind bursts and subsequent development by westerly wind bursts as observed during 2014-2016 is consistently retrieved. We show in addition that individual wind bursts may control the main characteristics of the event only during its early development while sequences of consecutive wind bursts have more important cumulative effects. Another important result from the present analysis is the significant statistical occurence of the delayed super El Nino (around 20-30%) compared with the one of directly formed super events as that of 1997-1998. Such a high occurence is directly linked to the random evolution of wind bursts and is retrieved here for all phases of the El Nino-Southern Oscillation used for the initiation of the ensemble experiments. These results suggest that the delayed super El Nino is not an unusual type of super event and could reoccur in the future.