Sensitivity of Ice Drift to Form Drag and Ice Strength Parameterization in a Coupled Ice–Ocean Model

Abstract

A pan-Arctic sea-ice–ocean prediction system is assessed in terms of its ability to predict sea-ice velocity. This system is based on the Regional Ice Ocean Prediction System running operationally at the Canadian Centre for Meteorological and Environmental Prediction. A form drag parameterization is implemented in the system to allow spatially and temporally varying neutral drag coefficients depending on the sea-ice morphological characteristics. Simulated ice velocity is assessed using data from the International Arctic Buoy Programme, as well as ice motion derived from Environment and Climate Change Canada’s synthetic aperture radar automated ice-tracking system. Results indicate that introducing the form drag parameterization systematically increases the sea-ice velocity and exacerbates a positive bias in summer already present in the previous version in which constant neutral drag coefficients were used. The ice strength parameterization used in the model rheology is found to affect the simulated ice drift significantly. Introducing modifications to the ice strength formulation and the empirical parameters helped alleviate the ice velocity bias.