From Glacier to Coast: Seasonal Hydrographic Dynamics in the Ella Ø Fjord Complex, East Greenland

Abstract

Greenland's ice loss is increasing across the ice sheet due to enhanced surface melting and accelerated glacier discharge, contributing to sea level rise and potentially altering ocean circulation and marine ecosystems. Fjords play a key role in this process by linking the ocean and ice sheet, but currently a limitation is that most fjords in Greenland lack observational data, especially seasonal data sets. Using glacier‐to‐coast hydrographic sections from the Ella Ø fjord complex in East Greenland, we document strong seasonal variability. Summer conditions are characterized by ice‐free, warmer, and fresher surface waters, with clear glacier meltwater and precipitation signals confined to the upper 50 m and primarily to the inner fjord. In winter, the fjord is ice covered, with colder and saltier surface waters, weaker turbidity that is dominated by basal melt at depth, and only small fractions of glacier meltwater and local meteoric water. The Polar Water layer is warmer close to the marine‐terminating glacier during both seasons, without corresponding change in salinity. The observed seasonal change in Polar Water thickness of 40 m is consistent with the proposed thinning of the Polar Water layer along the Northeast Greenland shelf since the 2000s, suggesting that longer‐term changes are superimposed on a strong seasonal variability. Given that most freshwater from the Arctic Ocean flows southward along the East Greenland coast, influencing regional and potentially large‐scale ocean circulation, it is important to gain more insight into its seasonal variability across multiple locations to evaluate the robustness of reported longer‐term changes.