Statistical Characteristics of ENSO Events in CMIP5 Models

Abstract

By applying the historical-run outputs from 24 Coupled Model Intercomparison Project Phase 5 (CMIP5) models and the NOAA Extended Reconstructed SST V3b dataset (ERSST), the characteristics of different types of ENSO in the selected CMIP5 models, including cold-season-matured Eastern Pacific (C-EP) ENSO, warm- season-matured EP (W-EP) ENSO, cold-season-matured Central Pacific (C-CP) ENSO, and warm-season-matured CP (W-CP) ENSO, were examined in comparison with those in the ERSST dataset. The results showed that, in general, consistent with observations, EP ENSO events in most of the model runs were relatively much stronger than CP ENSO events, and cold-season-matured ENSO events were relatively much more frequent than warm-season-matured ENSO events for both EP and CP ENSO events. The composite amplitudes of ENSO events in most of the models were generally weaker than in ob- servations, particularly for EP El Nino and CP La Nina. Moreover, most of the models successfully reproduced the amplitude asymmetries between El Nino and La Nina for cold-season-matured EP and CP ENSO events, exhib- iting an average stronger/weaker EP El Nino/La Nina regime and a weaker/stronger CP El Nino/La Nina re- gime. Most of the models, however, failed to reproduce the observed regimes of stronger/weaker W-EP El Nino/ La Nina and weaker/stronger W-CP El Nino/La Nina.  Keywords: CMIP5, ENSO, eastern Pacific, central Pa- cific