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Free keywords:
sea ice; turbulent dispersion; Arctic
Abstract:
The single-particle dispersion of sea ice in the Fram Strait region is investigated using ice drift buoys deployed from 2002 to 2009 within the Fram Strait Cyclones and the Arctic Climate System Study campaigns. A new method to estimate the direction of the mean flow, based on a satellite drift product, is introduced. As a result, the bias in the dispersion introduced by the mean flow is eliminated considering only the displacements of the buoys in the cross-stream direction. Results show an absolute dispersion growing quadratically in time for the first 3 days and an anomalous dispersion regime exhibiting a strongly self-similar scaling following a 5/4 power law for time scales larger than 6 days persisting over the whole time series of length 32 days. The non-Gaussian distribution of the velocity fluctuations with a skewness of −0.15 and a kurtosis of 7.33 as well as the slope of the Lagrangian frequency spectrum between −2 and −1 are in agreement with the anomalous diffusion regime. Comparison with data from the International Arctic Buoy Program yields similar results with an anomalous dispersion starting after 10 days and persisting over the whole time series of length 50 days. The results suggest the presence of deformation and shear acting on the sea ice dispersion. The high correlation between the cross-stream displacements and the cross-stream wind velocities shows the important role of the wind as a source for the anomalous dispersion.
