Sea Ice Growth, Melt and Dynamics in an Increasingly Marginal Arctic

Abstract

As summer Arctic sea ice extent has retreated, the marginal ice zone (MIZ) has been widening and making up an increasing percentage of the summer Arctic sea ice. The MIZ is defined as the region of the ice cover that is influenced by waves, and for convenience here is defined as the region of​ the ice cover between ice concentrations of 15-80%. The MIZ is projected to become a larger percentage of the summer ice cover, as the Arctic transitions to ice free summers. We use​ a sea ice-mixed layer model that has a prognostic floe size distribution model including brittle fracture and form drag. The model has been compared and calibrated to FSD observations, satellite observation of sea ice extent and PIOMAS. We compare the processes of ice volume gain and loss in the ice pack to those in the​ MIZ to establish and contrast the relative importance of processes in the pack and MIZ, and the changes as the summer MIZ fraction increases and the amplitude of the seasonal sea ice growth/melt cycle increases. We compare the components of the sea ice volume budget in the 1980s and 2010s and then between the 2010s and the 2040s where almost the entirety summer sea ice cover has become MIZ.