Statistical Analysis of Sea Ice Ridges in the Fram Strait 2006–2020 and Simulations of the Deepest Keels

An empirical ridge statistic that correlates weekly level ice thickness with keel depth and weekly number of ridges was investigated using upward looking sonars (ULS) data from 2006 to 2020 in the Fram Strait. The applied methodology was similar to the previous studies for the Beaufort Sea. The data were divided into weekly segments. For each of them, level ice thickness (hi), the number of ridges (N) and the average (hk) and deepest (hk_deep) keel depth were calculated based on the Rayleigh criterion with a threshold of 2.5 m and a minimum keel draft of 5 m. The broader idea was to compare regions with different ice regimes, in order to see how the ridge statistics change and how well the model can handle these differences. In this paper, we compare the Beaufort Sea and the Fram Strait. Both have a positive correlation between level ice thickness and keel depth. Linear regressions hk=5.91+ 0.60hi and hk_deep=8.67+ 5.91hi with Pearson correlation coefficients r=0.48 and r=0.45, respectively, are established in this study, which are both lower than the Beaufort Sea results.