Overestimated Arctic warming and underestimated Eurasia mid-latitude warming in CMIP5 simulations

摘要

The surface air temperature (SAT) trends from historical simulations of the Coupled Model Intercomparison Project Phase 5 (CMIP5) were compared with observations for the period of 1955-2004. The observed spatial pattern of SAT trends was strikingly different from the CMIP5-historical simulations over mid- and high-latitude Northern Hemisphere. The strongest observed warming for the Eurasian Continent was over mid latitudes. However, the CMIP5 historical simulations indicated enhanced warming over higher latitudes, and the warming trends increased from low to higher latitudes. The zonal mean SAT trends indicated overestimated warming in high-latitude and underestimated warming in mid-latitude land over Northern Hemisphere in CMIP5 historical simulations, which resulted in opposite trends in the meridional temperature gradient over high latitudes compared with observations. The overestimated Arctic and underestimated Eurasia mid-latitude warming only occurred in cold season. Further comparison of the results of CMIP5 models from the Atmospheric Model Intercomparison Project and historical simulations revealed that model bias in sea surface temperature and the exaggerated response of temperature change to Arctic sea ice decline are possible reasons for poorly simulated Arctic and Eurasia mid-latitude temperature change.