Attribution of late summer early autumn Arctic sea ice decline in recent decades

Abstract The underlying mechanisms for Arctic sea ice decline can be categories as those directly related to changes in atmospheric circulations (often referred dynamic mechanisms) and the rest (broadly characterized thermodynamic processes). An attribution analysis based on self-organizing maps (SOM) method is performed determine relative contributions from these two types of August–October during 1979–2016. daily represented by 500-hPa geopotential height anomalies are classified into 12 SOM patterns, which portray spatial structures Oscillation Dipole, their transitions. Due counterbalance between opposite trends among circulation net effect small, explaining only 1.6% declining trend number days majority (95.8%) accounted processes not circulations, whereas remaining (2.6%) non-circulation cannot distinguished. closely associated with surface air temperature increase, increasing water vapor content, downward longwave radiation, temperatures over open ocean, well decreasing albedo. analogous extending seasonal coverage spring (April–October) same period supports dominating role forcing decadal-scale loss.