Modelled realistic daily variation in low winter sea-ice concentration over the Barents Sea amplifies Asian cold events

Abstract

The boreal wintertime atmospheric responses, especially cold events over central Asia, to low sea-ice concentration (SIC) with and without realistic daily variation over the Barents Sea are explored with the Community Atmosphere Model version 4.0 (CAM4.0). The results show that the general atmospheric responses to approximately equal winter-mean Arctic sea-ice loss with a similar pattern but with climatological versus realistic daily variation are different. With the forcing of low SIC with climatological daily variation, Asian cold events become a little longer and stronger than in the control experiment; this mainly results from the enhancement of a 500-hPa Ural anticyclonic anomaly. However, the low SIC forcing that includes realistic daily variability greatly intensifies central Asian cold events and the cyclonic anomaly downstream of the Ural anticyclone. Further analysis reveals that Asian cold events are closely associated with Arctic deep warming at an intraseasonal time scale, which is also the strongest in the perturbed experiment forced by low SIC with realistic daily variation. This work provides a better understanding of the linkage between sea-ice variation over the Barents Sea and central Asian cold events, which may improve extreme weather prediction. It also implies that it is necessary to force air–sea coupling models and atmospheric models with realistic daily SIC in the study of the relationship between Arctic sea ice and mid-latitude cold events.