Improved simulation of two types of El Nino in CMIP5 models

Using the coupled general circulation models (CGCMs) participating in phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5), simulations of the two types of El Nino event are evaluated. Previous studies using CMIP3 models pointed out that most of the models tend to simulate a single type of El Nino, and have serious problems in simulating the two types of El Nino independently. On the average, the CGCMs in CMIP5 have slightly better performance in simulating the two types of El Nino event independently with more distinct spatial patterns, compared to those in CMIP3. It is demonstrated that the precipitation response to Cold Tongue El Nino is one of the important factors in simulating the two types of El Nino independently in coupled models, and this precipitation response is closely related to the dry bias over the equatorial eastern Pacific.