Formation and distribution of sea ice in the Gulf of St. Lawrence: A process‐oriented study using a coupled ocean‐ice model

Abstract

A coupled ocean-ice model for the eastern Canadian shelf is used to examine main physical processes affecting sea ice conditions in the Gulf of St. Lawrence (GSL) and adjacent waters. The coupled model is based on NEMO and uses OPA9 as the ocean circulation component and LIM2 as the ice model. The coupled model is forced by atmospheric reanalysis fields produced by Large and Yeager (2004). The model results are used to examine the roles of thermodynamics and dynamics on sea ice distributions and patterns of ice production and melting, and the influence of ice capping on the circulation in the study region. Analysis of model results indicates that local production of sea ice is important in shallower areas over the northern and western GSL. Equatorward advection of sea ice from the St. Lawrence Estuary is affected significantly by the Gaspe Current. An index is used to quantify the relative importance of thermodynamic and dynamics of sea ice in the GSL. It is found that both thermodynamics and dynamics are important over most of the GSL, except for waters around Anticosti Island, in the southeastern Gulf, and over the eastern Scotian Shelf, where dynamics (or sea ice movements) are the most important mechanism for the presence of sea ice. The study also demonstrates that ice capping significantly reduces the strength of the winter circulation in the GSL.

Emergent Relationships Among Sea Ice, Longwave Radiation, and the Beaufort High Circulation Exposed Through Parameter Uncertainty Analysis

“…While these parameters adopt constant values in the model, it is known that they can have strong temporal and spatial variability, for instance, in response to snow density and snow metamorphism (Meinander et al, 2013;Sturm et al, 1997). Other studies have also identified that the stability of the atmospheric boundary layer could affect clouds and sea ice, through modulations of the turbulent exchanges of heat and water vapor (Kay et al, 2016;Urrego-Blanco & Sheng, 2014). In EHV0, the air-ocean turbulent exchanges are estimated using Monin-Obukhov similarity theory, in which vertical gradients of momentum, temperature, and humidity are functions of coefficients C s and C u for stable and unstable atmosphere conditions, respectively, as defined by Large and Pond (1982).…”

Mapping the long‐term influence of river discharge on coastal ocean chlorophyll‐a

“…Flow to the Gulf of St. Lawrence increases in warm months with snow melt. Sea ice forms in the Gulf in December and begins to spread seaward (east), eventually covering most of the Gulf, reaching its maximum extent in March, thereafter beginning to melt (Urrego‐Blanco & Sheng, 2014). The lack of distinctive areas of moderate to high correlation in the Gulf of St. Lawrence from the spatiotemporal analysis are likely due to a lack of data due to cloud cover and masking or inaccurate estimates of chl‐ a due to ice cover (Fig.…”

“…The lack of distinctive areas of moderate to high correlation in the Gulf of St. Lawrence from the spatiotemporal analysis are likely due to a lack of data due to cloud cover and masking or inaccurate estimates of chl‐ a due to ice cover (Fig. 5A) (Urrego‐Blanco & Sheng, 2014). The Gulf of St. Lawrence is known to be highly productive, but higher productivity in the eastern region, has previously been attributed to upwelling (Savenkoff et al., 2001).…”

Sea Ice Interannual Variability and Sensitivity to Fall Oceanic Conditions and Winter Air Temperature in the Gulf of St. Lawrence, Canada

“…All charts are then gridded on a 0.01°latitude by 0.015°longitude grid (approximately 1 km resolution). Following Table 3.1 of the Canadian Ice Service (2005) documentation, thickness (and therefore volume) is estimated from the mean thickness of stages of ice growth whether it is new ice (stage 1, <10 cm: 5 cm), nilas (stage 2, <10 cm): 5 cm), gray ice (stage 4, 10-15 cm: 12.5 cm), gray-white ice (stage 5, 15-30 cm: 22.5 cm), thin first-year ice (stage 7, 30-70 cm: 50 cm), medium first-year ice (stage 1•, 70-120 cm: 95 cm) and thick first-year ice (stage 4•, >120 cm: 160 cm), following a practice used by Peterson and Prinsenberg (1990) and Prinsenberg et al (1997) and routinely used for the validation of sea ice volume production in numerical models of the Gulf of St. Lawrence (Brickman & Drozdowski, 2012;Brickman et al, 2016;Saucier et al, 2003;Smith et al, 2013;Tang et al, 2008;Urrego-Blanco & Sheng, 2014). Prior to 1983, the CIS reported ice categories into fewer classifications using a single category of first-year ice (≥30 cm) with a suggested average thickness of 65 cm.…”