Consequences of poor representation of Arctic sea‐ice albedo and cloud‐radiation interactions in the CMIP5 model ensemble

Abstract

AbstractClouds significantly influence the Arctic surface energy budget and a realistic representation of this impact is a key for proper simulation of the present‐day and future climate. Considerable across‐model spread in cloud variables remains in the fifth phase of Coupled Model Intercomparison Project ensemble and partly explains the substantial across‐model spread in the surface radiative effect of the clouds. In summer, the extensive model differences in sea‐ice albedo, which sets the potential of the cloud‐albedo effect, are strongly positively correlated to their cloud radiative effect. This indicates that the model's sea‐ice albedo not only determines the amount, but also the sign of its cloud radiative effect. The analysis further suggests that the present‐day annual amplitude of sea‐ice cover depends inversely on the model's sea‐ice albedo. Given the present‐day across‐model spread in sea‐ice albedo and coverage, a transition to a summer ice‐free Arctic ocean translates to a model‐span of increased surface shortwave absorption of about 75 W m−2.