Integrating Regional Ice Charts and Copernicus Sea Ice Products for Navigation Risk in Alaskan Waters

Abstract

As climate change continues to reshape marginal ice zones in the Arctic, accurate and reliable sea ice data are critical for ensuring maritime safety. This study compares regional ice charts from the Alaska Sea Ice Program with satellite derived Copernicus sea ice concentration data to evaluate spatial and temporal discrepancies in ice representation across Alaskan waters from January 2010 to March 2025. Daily Arctic Sea Ice Program polygons were aligned with Copernicus grid points in a common UTM framework, and residuals were computed to quantify systematic differences. Results show that Copernicus consistently underestimates ice concentration relative to Arctic Sea Ice Program, particularly in nearshore and marginal ice zones affected by land-spillover and mixed-pixel effects such as those observed in Cook Inlet. Empirical Orthogonal Function analysis shows that both datasets capture the same dominant physical modes of sea ice variability, with the first mode representing the annual freeze thaw cycle and the second reflecting marginal ice-zone dynamics. To assess operational implications, vessel Automatic Identification System data were combined with Alaska Sea Ice Program ice charts using the IACS POLARIS Risk Index Outcome framework. Approximately 36 percent of AIS observations within ice affected waters corresponded to negative Risk Index Outcome values, indicating that vessels frequently operated under elevated-risk conditions. These findings demonstrate that regional charts and Copernicus provide complementary capabilities that together enable more accurate and operationally meaningful Arctic navigation and risk assessments.