Arctic sea ice variation in the Northwest Passage in 1979–2017 and its response to surface thermodynamics factors

Abstract

Sea ice conditions in the Canadian Arctic Archipelago (CAA) play a key role in the navigation of the Northwest Passage (NWP). Limited by observed sea ice thickness data, the research of temporal and spatial variation of sea ice in the NWP is insufficient. Based on the observed sea ice concentration and simulated thickness data, the temporal and spatial characteristics of sea ice concentration, extent and thickness from 1979 to 2017 in the NWP of the CAA were studied. The more specific pathways of the northern and southern routes of the NWP were evaluated. Against the background of the rapid retreat of Arctic sea ice, the 39-year observed sea ice concentration and extent of the NWP exhibited a relatively large decreasing trend in summer and fall, while heavy sea ice conditions were maintained in winter and spring, with slightly increasing trend in some subregions. The sea ice thickness in most subregions of the NWP showed a decreasing trend, with exception of Lancaster Sound. The sea ice thickness was larger along the northern route than the southern routes. The significant correlation (p < 0.05) between sea ice and surface air temperature (SAT) and sea surface temperature (SST) in the NWP suggested that the surface thermodynamic factors had a greater impact on sea ice in the summer and fall, and the variations of sea ice concentration were more closely correlated with the surface thermodynamic factors than sea ice thickness. The SST had a higher correlation with sea ice concentration than SAT, while SAT exhibited a higher correlation with sea ice thickness than SST. The remaining sea ice concentration and thickness in the fall, associated with the summer and fall SAT and SST, contributed to the formation of sea ice in the following winter and spring. The heat content and mixed layer depth were also be considered as the vertical thermodynamic factors to the sea ice condition in the NWP.