Effects of Seasonal Ice Coverage on the Physical Oceanographic Conditions of the Kitikmeot Sea in the Canadian Arctic Archipelago

Abstract

The Kitikmeot Sea is a semi-enclosed, east-west waterway in the southern Canadian Arctic Archipelago (CAA). In the present work, the ice conditions, stratification and circulation of the Kitikmeot Sea are diagnosed using numerical simulations with a 1/12 • resolution. The physical oceanographic conditions of the Kitikmeot Sea are different from channels in the northern CAA due to the existence of a substantial ice-free period each year. The consequences of such ice conditions are twofold. First, through fluctuations of external forcings, such as solar radiation and wind stress, acting directly or indirectly on the sea surface, the seasonal ice coverage leads to significant seasonal variations in both stratification and circulation. Our simulation results suggest that such variations include freshening and deepening of the surface layer, whose salinity can reach as low as 15 psu during the peak runoff season, and significantly stronger along-shore currents driven directly by the wind stress during the ice-free season.The second consequence is that the sea ice is not landfast but can move freely during the melting season. By analyzing the relative importance of thermodynamic (freezing/melting) and dynamic (ice movement) processes to the ice dynamics, our simulation results suggest that there exists a net inflow of sea ice into the Kitikmeot Sea, which melts locally each summer. The movement of sea ice thus provides a significant freshwater pathway, which contributes ∼ 14 km 3 /year of freshwater to the Kitikmeot Sea on average, equivalent to a third of freshwater input from runoff from the land.

High interannual surface pCO2 variability in the Southern Canadian Arctic Archipelago's Kitikmeot Sea

“…There is good agreement in the pCO 2 (sw) values between the EC tower and the ONC mooring in May, June, and October 2017 (Figure 5b) and in May and June 2018 (Figure 5c). The breakdown of stratification at the end of the ice-free summer period and over the winter (Xu et al, 2021) may explain the good agreement between the EC tower and the ONC mooring at these times. In June 2017 the two systems diverge, the pCO 2 (sw) at the ONC mooring decreases due to a spring bloom (Duke et al, 2021) whereas pCO 2 (sw) from the EC tower does not.…”

“…The Kitikmeot sea is nutrient-limited (Back et al, 2021), and as a result chlorophyll concentrations are also low in the region (Kim et al, 2020). Modelling results suggest that the stratification regime in Dease Strait and Queen Maud Gulf is characterised by a ~40 m warm fresh surface layer and a cold salty bottom layer which extends down to around 100 m (Xu et al, 2021). Coronation Gulf has a three layer regime composed of a 40 m warm fresh surface layer, a colder salty layer down to 100 m and a stable deep layer down to 350 m (Xu et al, 2021).…”

“…Modelling results suggest that the stratification regime in Dease Strait and Queen Maud Gulf is characterised by a ~40 m warm fresh surface layer and a cold salty bottom layer which extends down to around 100 m (Xu et al, 2021). Coronation Gulf has a three layer regime composed of a 40 m warm fresh surface layer, a colder salty layer down to 100 m and a stable deep layer down to 350 m (Xu et al, 2021). Vertical mixing in the Kitikmeot Sea is prohibited by strong stratification throughout most of the year; however after sea ice breakup wind driven mixing gradually deepens the surface mixed layer resulting in an almost fully mixed water column in Dease Strait (Xu et al, 2021).…”

“…Coronation Gulf has a three layer regime composed of a 40 m warm fresh surface layer, a colder salty layer down to 100 m and a stable deep layer down to 350 m (Xu et al, 2021). Vertical mixing in the Kitikmeot Sea is prohibited by strong stratification throughout most of the year; however after sea ice breakup wind driven mixing gradually deepens the surface mixed layer resulting in an almost fully mixed water column in Dease Strait (Xu et al, 2021). The oceanographic boundary for the Kitikmeot Sea has been designated as where the shelf shoals to <30 m in the west (Dolphin and Union Strait) and northeast (Victoria Strait) (Williams et al, 2018).…”

Variability in sea ice carbonate chemistry: A case study comparing the importance of ikaite precipitation, bottom ice algae, and currents across an invisible polynya

“…In the winter, Dease Strait is covered by landfast first-year sea ice that typically consolidates in early November, and breaks up in mid-July (Galley et al, 2012, Xu et al, 2021. The strait is relatively shallow (max depth ~100 m), and surface waters are somewhat less saline (~29) than most of the Archipelago due to high river discharge and bounding sills to the east and west (Williams et al, 2018;Xu et al, 2021). The region is highly nutrient limited, with nitrate concentrations amongst the lowest measured anywhere in the Arctic (Back et al, 2021), however a modest bottom-ice algae bloom still occurs in the spring, peaking in late-May (Campbell et al, 2016).…”