The Average Shape Of Sea Ice Ridge Keels
Through analysis of over 64,000 sea ice ridge profiles identified from upward-looking sonars, we identify a well-defined average shape for ridge keels. The average shape of keels is concave and not triangular as commonly assumed, and the main reason for this is horizontal shear during ridge formation, demonstrated in the analysis of more than 100 million modeled ridges.
This research is important for improving model parameterizations that utilize average morphological shapes to simulate landfast sea ice, form drag, and the compressive stress of the pack, in turn affecting sea ice drift and deformation, and the protection of Arctic coasts from erosion.
Through analysis of over 64,000 sea ice ridge profiles identified from upward-looking sonars, we identify a well-defined average shape for ridge keels. The shape of keels tends to be concave and not triangular as commonly assumed. Because of this result, we put forward a new description of an average ridge cross-section that has a concave shape. This new definition allows an average ridge cross-section to be constructed with a value for a single parameter. Using a mathematical sea ice ridge model, we calculated statistics from more than 100 million simulated keels for a range of ridge building conditions. The modeling results agree with observations and indicate the concave shape of the average ridge profile arises from variations in the horizontal shearing of the ice cover when ridges form. This has important implications for modeling landfast sea ice, form drag, and the compressive stress of the pack in Earth System Models such as E3SM.