Sea ice motion and open water area at the Ronne Polynia, Antarctica: Synthetic aperture radar observations versus model results

Abstract

This study deals with observations and simulations of the evolution of coastal polynias focusing on the Ronne Polynia. We compare differences in polynia extent and ice drift patterns derived from satellite radar images and from simulations with the Finite Element Sea Ice Ocean Model, employing three atmospheric forcing data sets that differ in spatial and temporal resolution. Two polynia events are analyzed, one from austral summer and one from late fall 2008. The open water area in the polynia is of similar size in the satellite images and in the model simulations, but its temporal evolution differs depending on katabatic winds being resolved in the atmospheric forcing data sets. Modeled ice drift is slower than the observed and reveals greater turning angles relative to the wind direction in many cases. For the summer event, model results obtained with high-resolution forcing are closer to the drift field derived from radar imagery than those from coarse resolution forcing. For the late fall event, none of the forcing data yields outstanding results. Our study demonstrates that a dense (1-3 km) model grid and atmospheric forcing provided at high spatial resolution (< 50 km) are critical to correctly simulate coastal polynias with a coupled sea-ice ocean model. Key Points Observations on polynia extent and ice motion based on SAR images Influence of wind forcing on sea ice motion in a coupled sea ice ocean model High resolution sea ice motion data from SAR observations for model validation ©2013. American Geophysical Union. All Rights Reserved.