Assessing Sea Ice Trafficability in a Changing Arctic

Abstract

Arctic sea ice has undergone rapid changes during the last few decades, with negative implications for over-ice travel and on-ice operations, which benefit from services provided by the sea ice. A Parameter-based Trafficability Hierarchy (PATH) is presented here as a framework for developing quantitative assessment strategies that can guide planning and execution of operations on or near sea ice and quantify the impacts of recent changes on ice use. A PATH assessment has been completed for three case studies in Arctic Alaska. These cases, which correspond to a range of different icescapes and ice uses, identify and quantify different parameters linked to trafficability and safe operations. For ice road applications, PATH was used to determine an ice thickness compensation factor, a factor increasing the minimal thickness threshold for operations, to help translate sporadic auger ice thickness measurements along the Kotzebue–Kiana community ice road into an envelope for safe operations. A compensation factor as high as 1.5 was found to be necessary to ensure safety because of the high local thickness variability that is currently a concern for ice road operators. A PATH assessment of ice roughness for ice trail routing at Utqiaġvik draws on satellite remote sensing and is relevant for over-ice travel in general, including escape, evacuation, and rescue. We compared the routing of local snowmobile trails with Synthetic Aperture Radar (SAR) data products to identify specific ranges of ice conditions, roughness, and topography favored for ice trail construction. The same combination of data sources was used to identify potentially beneficial trail routes. Finally, an ice stability and safety assessment was completed for ice road construction and maintenance by industry near the Northstar Island oil production facility. We evaluated small-scale ice displacement data obtained from SAR interferometry to infer internal ice strain and stress and used these data in assessing the potential for fractures to reduce load-bearing capacity.

Mapping pan-Arctic landfast sea ice stability using Sentinel-1 interferometry

“…InSAR has also been shown to reveal plausible rheologies for landfast ice (Dammert et al, 1998) and has been used to determine the origin of internal ice stresses (Berg et al, 2015). Combined with inverse modeling, InSAR enables us to determine ice deformation modes (Dammann et al, 2016), rates, and the associated stress and fracture potentials (Dammann et al, 2018b). These studies have demonstrated (1) the potential of In-SAR as a tool for assessing landfast ice dynamics and stability through local case studies and (2) its utility as a planning tool for on-ice operations (Dammann et al, 2018a, b).…”

Landfast sea ice stability – mapping pan-Arctic ice regimes with implications for ice use, subsea permafrost and marine habitats

“…Prior studies have demonstrated the utility of InSAR over landfast ice as a planning tool for on-ice operations (Dammann et al, 2018a;Dammann et al, 2018b) but we argue here that such utility and potential applications also extend to maritime activities and shipping. In regards to the latter, vessel traffic typically does not traverse landfast ice.…”

“…As an example, on shorter time scales, industry ice 30 roads would be able to accommodate less strain than community ice trails due to different mode of transportation and user specific needs. Further steps to identify such thresholds are outlined in Dammann et al (2018a).…”

Marine mammal ecology and health: finding common ground between conventional science and indigenous knowledge to track arctic ecosystem variability

“…Three insights emerged from the study, including: (1) tracking ice conditions along ice trails revealed clear interannual variability in the thickness of the shore-fast ice, (2) documenting trail building and hunting strategies demonstrated how the community responds to variability, and (3) developing CS information resources for the community facilitated interaction with hunters and demonstrated project relevance to environmental challenges facing the community. These insights provided a foundation for the development of a framework to quantify the impacts of loss of sea ice on safety of onice travel and operations across a range of difference icescapes and ice uses (Dammann et al 2018), which remain some of the biggest challenges for Alaska Native marine mammal hunters (Huntington et al 2017). Motivated by the need to forecast safe sea-ice conditions at operational timescales (<10 days), insights from CS-IK sea ice partnerships were included in exploring how IK fits into a forecaster toolbox to support useful sea-ice information products (Deemer et al 2018).…”