Sea Ice Drift

In this chapter, sea ice drift is discussed in terms of statistical properties of individual Lagrangian trajectories. It is first shown that the Arctic sea ice velocity field can be objectively decomposed into a mean field and fluctuations. The mean field shows intra-annual (between winter and summer) as well as some interannual variability. The fluctuations, defined as the remaining part of the velocity field after removing the mean field, share similarities with fluid turbulence, such as a Kolmogorov-like scaling of the power spectral density, a ballistic regime within an inertial range of motion, or intermittency. However, significant differences are also observed: sea ice velocity distributions are clearly much more spread than Gaussian statistics, intermittency is more pronounced, and sea ice accelerations cannot be explained from wind stress statistics. These differences argue for a non-linear response of sea ice to forcing.