Variation in the Impact of ENSO on the Western Pacific Pattern Influenced by ENSO Amplitude in CMIP6 Simulations

The Western Pacific pattern (WP) is one of the most consequential atmospheric teleconnections during boreal winter, as it profoundly influences weather extremes and climate variability across Eurasia and North America. The El Nino-Southern Oscillation (ENSO) is suggested to be a crucial external forcing of WP variability. In this study, we meticulously evaluated the capability of 56 coupled climate models from the Coupled Model Intercomparison Project 6th phase (CMIP6) in replicating the winter ENSO-WP connection. Our results reveal notable diversities in the portrayal of the winter ENSO-WP relation across CMIP6 models. This model diversity in the ENSO-WP connections primarily stems from the spread of the models' simulated ENSO amplitude. Specifically, models with enhanced ENSO amplitudes exhibit intensified sea surface temperature (SST) anomalies in the equatorial central-eastern Pacific. This enhancement of SST anomalies faciliates stronger atmospheric convective anomalies, especially in the extratropical eastern Pacific and the tropical western North Pacific. Of particular note is the intensified atmospheric convective anomalies in the tropical western North Pacific, which exert a pivotal role in shaping the WP through initiating a distinct atmospheric teleconnection pattern.

Automated summary

The Western Pacific pattern (WP) plays a significant role in weather extremes and climate variability across Eurasia and North America during boreal winter, and it is influenced by the El Nino-Southern Oscillation (ENSO). This study evaluates the ability of 56 coupled climate models to replicate the winter ENSO-WP connection and finds notable diversities in how the models portray this relationship, primarily due to the spread of simulated ENSO amplitude.