Drivers of Interannual Sea Ice Concentration Variability in the Atlantic Water Inflow Region North of Svalbard

Abstract

Sea ice concentration along the continental margin of the Arctic Ocean is influenced by a multitude of factors, including local freezing and melting due to atmospheric forcing, lateral advection of sea ice by winds and ocean currents, and melting from below by warm Atlantic Water (AW). Here, we characterize the evolution of sea ice concentration in an area on the continental shelf break north of Svalbard in the period between 2012 and 2019. During this period, a semi-regular seasonal pattern in sea ice concentration was interrupted by three anomalous seasons; a high ice anomaly during autumn 2014 and low ice anomalies during spring 2016 and 2018. Neither type of anomaly can be explained by abnormal upper ocean heat content as measured by an ocean mooring located near the shelf break. Instead, we find that the predominant driver of interannual sea ice concentration variability during this period was variations in large-scale ice drift. While heat flux from the ocean cannot explain the interannual variability, it plays a key role in maintaining periods of open water in the AW inflow region despite freezing air temperatures during most of the year. These results are consistent with the sea ice concentration flux divergence from satellite records, which suggests that the southern continental slope of the Eurasian Basin is an important melting area for sea ice advected in from the north.