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

Yingjie Wang,Na Liu,Zhanhai Zhang

doi:10.3389/fmars.2021.650909

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.

Highlights

The Arctic Ocean has been warming over the past few decades (Zhang, 2005; Polyakova et al, 2006)
To identify the impacts of Pacific water on Arctic sea ice, the present study investigated the effect of the Pacific inflow on sea ice reductions during the freezing period in 2017 by quantifying the heat transport from the Pacific inflow based on hydrological section data and mooring data in the Chukchi Sea
The area of anomalous sea ice reduction corresponded to the known Pacific inflow pathways, and the overlapping sea ice reduction and Pacific intrusion distribution domains suggest a causal link to the Pacific inflow through the Bering Strait

Summary

Introduction

The Arctic Ocean has been warming over the past few decades (Zhang, 2005; Polyakova et al, 2006). The Arctic Sea ice cover is changing, where the sea ice extent in September has decreased since 1979 at a rate of 9% per decade (Serreze et al, 2007b), and the overall mean winter sea ice thickness decreased by 1.75 m in the central Arctic between 1980 and 2008 (Kwok and Rothrock, 2009). Within the Arctic Ocean, one of the main areas undergoing sea ice reduction is the western Arctic. Ice Reduction Due to Oceanic Heat the flow has remained northward and the sea ice retreat occurred in patterns consistent with the known Chukchi flow pathways via Herald Valley, the Central Channel, and Barrow Canyon (Weingartner et al, 1998; Woodgate et al, 2005a). The area with anomalous sea ice reduction corresponds to the area where the warm Pacific Summer Water is observed immediately beneath the surface mixed layer (20–60 m; Coachman et al, 1975; Shimada et al, 2006)

Methods

Results

Conclusion