Long-term Variation Of Sea Ice In The Canadian Arctic Archipelago And Its Response To Meteorological Factors

As an important gateway for Arctic fresh water outgoing,variation of sea ice in the Canadian Arctic Archipelago will have a profound impact on the hydrological conditions,natural environment and ecosystem of the North Atlantic and its downstream.In addition,the variation of sea ice in the Canadian Arctic Archipelago will have a significant impact on the Northwest passage.However,due to the limitation of the observation data in time and space,the current research on the process and mechanism of sea ice change in the Canadian Arctic Archipelago is insufficiently.In this paper,the temporal and spatial variation characteristics of sea ice in Canadian Arctic Archipelago from 1979 to 2017 are comprehensively analyzed based on the sea ice concentration data of the National Sea Ice and Snow Center and the simulated sea ice thickness and sea ice drift velocity data.According to the sea ice concentration and thickness distribution and light ice probabilities from June to October,the specific navigation pathways of the south and north routes of the Northwest passage are evaluated.The sea ice in the Canadian Arctic Archipelago displayed significant differences in the spatial distribution among different seasons.The sea ice concentration was higher in spring and winter and lower in summer and fall.The sea ice concentration was higher in the northern area of domain and lower in the southern area.The melting season of Canadian Arctic Archipelago was longer,especially in the southern area and freezing was shorter.Different from the decreasing sea ice concentration trend in all every season across the entire Arctic,high concentration of sea ice was maintained in the Canadian Arctic Archipelago.During the 39 years,the sea ice extent and sea ice area showed a large decreasing trend in summer and fall and the largest trend occurred in the fall with the value of-0.33×10~5 km~2/10a and-0.41×10~5 km~2/10a(all passed 95%significance test).The decreasing trend was larger in the southern area than northern area.The sea ice thickness in the Canadian Arctic Archipelago increased from October to April,with its maximum of 2.60 m occurring in April and its minimum of 0.62 m occurring in September.In general,the sea ice thickness was greater in the southern area than northern area.Except Jones sound and Lancaster sound,the sea ice thickness of Canadian Arctic Archipelago showed a decreasing trend(-0.19 m/10a,passed 95%significance test)with larger trend in the southern area and smaller in the northern area.The sea ice thickness showed a significant decreasing trend in all seasons,and larger in summer and fall with a largest rate(-0.29 m/10a,passed 95%significance test)in August.According to sea ice concentration and thickness from June to October,the sea ice in the southern routes especially the PRI(Prince Regent Inlet)route was lighter than northern route.Combined with the distribution of sea ice concentration and sea ice thickness and the probability of light ice condition in 39 years,there are differences in the more specific navigation pathways of the south routes and the north routes according to the sea ice concentration and sea ice thickness,respectively.The same specific pathway for the southern routes was from south side of the Queen Maud Gulf to the center of Prince Regent Inlet.For the northern route,the same pathway was the north side of Viscount Melville Sound.In the upstream of the CAA,sea ice imported through the QEI-S,QEI-N and sea ice exported through the Amundsen Gulf and M’Clure Strait.In general,there was a large sea ice export in spring(March—may)and a large sea ice import in late summer and early fall(July—September)in the upstream of the Canadian Arctic Archipelago.In the downstream of the CAA,sea ice exported through Jones Sound and Lancaster Sound with smaller export in late summer to early fall.Most of the sea ice exported is produced in the Canadian Arctic Archipelago.In the Canadian Arctic Archipelago,the input of sea ice in the upstream is significantly enhanced,while the output flux of sea ice in the downstream is increased.The surface air temperature(SAT)and sea surface temperature(SST)in the Canadian Arctic Archipelago showed the increasing trend of 0.52℃/10 and 0.12℃/10a(passed 95%significance test).Compared with the northern area,the stronger warming was occurred in the southern area.The correlation results between the sea ice and atmospheric and oceanic surface thermodynamic factors including SAT and SST in the Canadian Arctic Archipelago suggested that in summer and fall,SAT and SST have great influence on sea ice.Compared with sea ice thickness,sea ice concentration has higher correlation with SAT and SST.The SST had a higher correlation with sea ice concentration than SAT,whereas the SAT had a higher correlation with sea ice thickness than SST.The sea ice thickness in the winter and spring was dominated by the remaining sea ice concentration and thickness,which was affected by SAT and SST in the previous summer and fall.The sea ice drift flux of Amundsen Gulf and M’Clure Strait were highly correlated with wind velocity.The sea ice drift flux of QEI-S and QEI-N was affected by wind velocity and sea ice conditions in the Canadian Arctic Archipelago.The sea ice imported from the Arctic Ocean has a great contribution to the sea ice drift flux from Lancaster sound.