a, The trends during the ice decay season (September to February). b, The trends during the ice growth season (March to August). The Pearson coefficients are given in the top right of each panel (n = 1,727 for each). The linear least-squares approximation during ice decay is −1.28 (Hs trend) + 0.02, with a 95% confidence interval of (−1.39, −1.16) for the slope. During ice growth, it is −1.03 (Hs trend) + 0.01, with a 95% confidence interval of (−1.12, −0.94) for the slope.