Small-scale deformation of an Arctic sea ice floe detected by GPS and satellite imagery

Abstract

Small-scale (~100 to 200 m) deformations of an Arctic sea ice floe were detected from multiple GPS-equipped buoys that were deployed on the same ice floe. Over a nine-month period three deformation events were recorded. At each case the event was of limited duration, each lasting less than a day. The events were highly compressive in nature with the area occupied by the buoy array decreasing by over half of the original area. The strain rate during the deformation, of the order of 10-5 s-1 , is about three orders of magnitude larger than previous estimates for brittle fracturing for cracks of about 100 m in length. On the 2-day time scale, the strain rate became too small and none of the deformation events could be detected. This suggests that satellite data with longer time scales may significantly underestimate the amount of intermittent, small-scale brittle failure of total deformation. Taken as a whole, our results show the influence that large-scale wind stress can have on small-scale deformation. However, it is important to note that the impact of largescale wind stress is also dependent on the properties of sea ice as well as on the spatial and temporal evolution of the underlying forces that influence the fracturing process.

Resolving Fine-Scale Surface Features on Polar Sea Ice: A First Assessment of UAS Photogrammetry Without Ground Control

“…Taking this further, colour thresholding, derived from the colour distribution histograms of the images, could be used to identify and track melt pond expansion, permitting estimation of the surface heat budget between the ice and atmosphere during sea ice decay [60]. Correlation-based image tracking techniques have already showed satisfactory outcomes in sea ice displacement retrieval from ENVISAT data [61], and similar approaches could be applied to time series of UAV-SfM orthomosaics to track small-scale motion and deformations, provided the UAS orthomosaics are accurately georeferenced [62]. The derivative of strain rates is a fundamental factor in multi-temporal sea ice stability research [34], and is a scale-dependent variable which cannot be linearly extrapolated from coarse-scale space observation [7].…”

Annual Cycles of Sea Ice Motion and Deformation Derived From Buoy Measurements in the Western Arctic Ocean Over Two Ice Seasons

“…The δ 15% at the 1‐hr scale extrapolated from the linear relationship with the logarithm of temporal scale decreased to less than 5% for all seasons. This implies that extreme ice deformation events occur over very small areas in linear kinematic features, that is, cracks and ridges, which can be considered as small‐scale brittle failure of the ice pack (Hwang et al, 2015). For both ice seasons, δ 15% decreased substantially from autumn to winter.…”

Arctic Climate Change, Economy and Society (ACCESS): Integrated perspectives

“…In addition, mean sea-ice thickness declined from more than 3 m down to less than 2 m (Renner et al 2014 ; Lindsay and Schweiger 2015 ), leading to a stark reduction in multiyear ice (Comiso 2012 ). Other Arctic sea-ice characteristics have also started to change and will likely continue to do so, like the length of the sea-ice-free season, earlier break up and later freeze up, the occurrence of melt ponds and the under ice topography (e.g., Hwang et al 2015 ; Divine et al 2016 ). All of these changes must be documented and understood, as they all play a role in the Arctic climate system, but they also have a direct impact on the human use of the Arctic.…”

“…The project provided contributions related to the impacts of climate change on the natural environment in the Arctic. Some examples include new direct and satellite-based observations of sea-ice properties (Hwang et al 2015 ; Divine et al 2016 ), atmospheric conditions (Gascard et al 2017 and references therein) and sea state (Dmitrenko et al 2014; Oziel et al 2016 ); development of a method to design better observation networks (Kaminski et al 2015 ); data analysis and modelling to improve scenarios of future sea ice and ocean (Gascard 2012 ; Gascard et al 2017 ). The project used much of these findings to inform studies on the impacts of climate change on society including costs and benefits of off-shore resource extraction (Petrick et al 2017 ), tourism, marine transportation, salmon ( Salmo salar ) farming in Norway, and different scenarios (model or narrative based) of future development for example for the maritime Arctic (Brigham 2015 ) and fisheries (Eide 2017 ).…”