Performance Evaluation of CMIP6 Models in Simulating the Dynamic Processes of Arctic-Tropical Climate Connection During Winter

In this study, the performance of 24 Coupled Model Intercomparison Project Phase 6 (CMIP6) models in simulating the dynamic processes of Arctic sea ice concentration (SIC)- and El Ni & ntilde;o-Southern Oscillation (ENSO)- forced teleconnection during winter is subjectively and objectively evaluated. The Arctic SIC-forced teleconnection is associated with a warm Arctic-cold Eurasian pattern of surface temperature (T2m), a low Arctic-high Eurasian pattern of sea level pressure (SLP), and a southeastward propagating wave-train originating from Arctic in the upper troposphere. The ENSO-forced teleconnection is associated with a poleward propagating wave-train originating from tropical Pacific in the upper troposphere, a low North Pacific-high Arctic pattern of SLP, and a cold North Pacific-warm Greenland pattern of T2m. The metrics of Taylor skill scores and Distance between indices of simulation and observation (DISO) are used to objectively and quantitatively evaluate the performance of models. The results of subjective and objective evaluation are essentially consistent. The CanESM5, MPI-ESM1-2-HR, EC-Earth3, and MRI-ESM2-0 models have the best performance in simulating the Arctic SIC-forced teleconnection. The CESM2, ACCESS-CM2, NESM3, NorESM2-MM, CAS-ESM2-0, MRI-ESM2-0 models have the best performance in simulating the ENSO-forced teleconnection. The two best-performing multi-model ensembles well reproduce the dynamic processes of the Arctic SIC- and ENSO- forced teleconnection. The diversity of model performance is attributed to the different skills of different models in simulating the interannual variability of Arctic SIC, the anomalous deep warm high over the Barents-Kara Seas, the interannual variability of tropical Pacific SSTs, and the wave number of poleward propagating Rossby waves. The connection between Arctic and tropical climates has an important influence on the climate in Northern Hemisphere. The Arctic sea ice-driven teleconnection may induce increased cold surges toward the low latitude regions of East Asia, while the El Ni & ntilde;o-Southern Oscillation (ENSO)-driven teleconnection may induce increased temperatures over northern North America and Greenland. The Coupled Model Intercomparison Project Phase 6 (CMIP6) models consists of state-of-the-art numerical models that are widely used in climate simulation and prediction. Hence, it is important to understand the performance of these models in simulating the dynamic processes of Arctic-tropical climate connection and the potential reasons. In this study, the dynamic processes in ocean-atmosphere associated with the Arctic sea ice- and ENSO- driven teleconnection are first analyzed using observed/re-analysis data. The performance of 24 CMIP6 models in simulating the dynamic processes of Arctic sea ice- and ENSO- driven teleconnection is then subjectively and objectively evaluated. The results indicate a diversity of performance in these models. This diversity are mainly caused by the different skills of models in simulating the interannual variability of SIC and ENSO as well as the associated atmospheric circulation anomalies. The performance of CMIP6 models has a diversity in simulating the dynamic processes of Arctic-tropical climate connection Best-performing multi-model ensembles with good skill in simulating dynamic processes of Arctic-tropical climate connection are selected The diversity in performance of models are affected by the skill of models in simulating the interannual variability sea ice and SSTs