Sea Ice Reduction During Winter of 2017 Due to Oceanic Heat Supplied by Pacific Water in the Chukchi Sea, West Arctic Ocean

Abstract

Over the past few decades, the areal extent of the Arctic sea ice cover has decreased. During the winter of 2017, negative sea ice concentration anomalies occurred mainly in the Chukchi Sea and adjacent seas. The properties of Pacific water through the Bering Strait have changed in recent years. To highlight the role of the Pacific inflow during the 2017 Arctic sea ice retreat, we used mooring measurements and conductivity–temperature–depth (CTD) data to quantify the effect of inflow on sea ice in the Chukchi shelf. In September 2017, the temperature of the Pacific inflow was relatively high compared with the multi-year average, especially in the shelf north of 69°N where the temperature anomaly was generally greater than 1°C. The average heat content of each CTD station in September 2017 ranged from 0.77 to 1.58 GJ m–2, where each station was 0.25 GJ m–2 higher than the multi-year average. In the central shelf of the Chukchi Sea, the temperature of the 25–40 m layer increased after late May, and decreased after mid-September. The Pacific inflow could have provided a large amount of heat to the Chukchi shelf, the accumulated convective heat transported to the surface from September to October was approximately 1.68 × 1018 J and it impacted the sea ice growth conditions.