Arctic Sea Ice on the Move: Wind-Driven Drift in a Changing Climate

While rising ocean surface temperatures are driving measurable changes in the Arctic Ocean, the impact of climate change on sub-ice circulation remains poorly understood. In this study, we use version 4, release 4 of the Estimating the Circulation and Climate of the Ocean solution (ECCO), built on the MIT general circulation model (MITgcm)—a dynamically consistent, Boussinesq, non-hydrostatic ocean model constrained by multi-decadal ocean and sea ice observations—well suited for capturing long-term trends in Arctic sea ice motion. We perform the first comprehensive evaluation of ECCO's seasonal and regional sea ice representation, along with a multi-decadal assessment of Arctic ice-ocean kinematics. Our results show that while the ECCO sea ice drift field and its circulation pattern closely match satellite-derived observations, the model has a stronger correlation with surface wind forcing than observations. In addition, ECCO produces a larger mean sea ice turning angle and higher drift speed ratios, suggesting the model discretization represents a stronger wind-ice coupling and lower internal ice resistance than what has been estimated from observations. Our framework offers an accessible strategy for the evaluation of ocean reanalyses and the identification of key drivers of near-surface kinematic variability in the Arctic.