Evaluation of Arctic sea ice simulation of CMIP6 models from China

Nine coupled climate models from China participating in the Coupled Model Intercomparison Project Phase 6(CMIP6)were evaluated in terms of their capability in ensemble historical Arctic sea ice simulation in the context of 56 CMIP6 models.We evaluated these nine models using satellite observations from 1980 to 2014.This evaluation was conducted comprehensively using 12 metrics covering different aspects of the seasonal cycle and long-term trend of sea ice extent(SIE)and sea ice concentration(SIC).The nine Chinese modelstended to overestimate SIE,especially in March,and underestimate its long-term decline trend.There was less spread in model skill in reproducing the spatial pattern of March SIC than in reproducing the spatial pattern of September SIC.The error of March SIC simulation was distributed at the margins of sea ice cover,such as in the Nordic Seas,the Barents Sea,the Labrador Sea,the Bering Sea,and the Sea of Okhotsk.However,the error of September SIC was distributed both at the margins of sea ice cover and in the central part of the Arctic Basin.Five of these nine models had capabilities comparable with the majority of the CMIP6 models in reproducing the seasonal cycle and long-term trend of Arctic sea ice.