34In this study, we use archives of Coupled Model Intercomparison Project Phase 5 (CMIP5) 35 to investigate changes in independency between two types of El Niño events caused by 36 greenhouse warming. In the observations, the independency between cold tongue (CT) and 37 warm pool (WP) El Niño events is distinctively increased in recent decades. The simulated 38 changes in independency between the two types of El Niño events according to the CMIP5 39 models is quite diverse, although the observed features are simulated to some extent in several 40 climate models.
41It is found that the climatological change after global warming is an essential factor in 42 determining the changes in independency between the two types of El Niño events. For 43 example, the independency between these events is increased after global warming when the 44 climatological precipitation is increased mainly over the equatorial central Pacific. This 45 climatological precipitation increase extends convective response to the east, particularly for 46 CT El Niño events, which leads to greater differences in the spatial pattern between the two 47 types of El Niño events to increase the El Niño independency. On the contrary, in models with 48 decreased independency between the two types of El Niño events after global warming, 49 climatological precipitation is increased mostly over the western Pacific. This confines the 50 atmospheric response to the western Pacific in both El Niño events; therefore, the similarity 51 between them is increased after global warming. In addition to the changes in the climatological 52 state after global warming, a possible connection of the changes in the El Nino independency 53 with the historical mean state is discussed in this paper. 54 55 56 3