Projected Changes of the Warm Arctic-Cold North American Pattern

The Warm Arctic-Cold North American (WACNA) pattern features opposing surface temperature anomalies, with centers over the Chukchi-Bering Seas (CBS) and the North American Great Plains. The pattern is mainly driven by meridional heat transport and damped by the generation of available potential energy through diabatic heating. The Canadian Earth System Model CanESM5, part of the Coupled Model Intercomparison Project Phase 6 (CMIP6), reasonably reproduces this pattern and its formation mechanisms. Future projections under the Shared Socioeconomic Pathway 8.5 (SSP5-8.5) suggest a significant weakening of WACNA with global warming. Notable changes in pattern intensity and spatial structure are anticipated, particularly a decrease in intensity over the CBS. WACNA changes are also found in 31 CMIP6 multi-model ensemble simulations. These changes are attributed to Arctic amplification associated with global warming, which diminishes the equator-to-pole temperature gradient and consequently reduces meridional heat transport, particularly over the CBS region.