Dynamics and thermodynamics of the ice/upper ocean system in the marginal ice zone of the Greenland Sea

Abstract

Measurements were made of the ice/upper ocean system in the marginal ice zone of the Greenland Sea during a 4‐day storm in which wind blew the ice south across a frontal region, coinciding with the ice edge that had existed when the storm began. In response to wind stress of about 0.2 Pa, a turbulent boundary layer developed under the ice that exhibited marked Ekman rotation in both mean velocity (average surface speed about 0.17 m s−1, deflection angle about 33°) and turbulent stress profiles (typical Reynolds stress about 0.1 Pa). Ablation of the ice undersurface increased rapidly after crossing the surface temperature front, and the observed melt rate corresponded with direct heat flux measurements in the oceanic boundary layer, with maximum upward heat flux of about 200 W m−2. We discuss overall momentum and energy balances, interpret observed boundary layer measurements with a numerical model, and show that molecular effects are important for heat and mass transport at the hydraulically rough ice‐ocean interface. We also develop a simple model for predicting ice melt from interfacial stress and temperature and salinity of the mixed layer.