Computed tomography (CT) scans of ice cores collected in two perennial ice patches at Ward Hunt Island, Nunavut, Canada.

Computed tomographic (CT) scanning was used (February 2018) for the analysis of ice cores collected with a 75 mm inner diameter SPIRE auger in July 2017 on two permanent ice patches on Ward Hunt Island, Nunavut, Canada. The coring was made vertically. The SIPRE was able to drill through bands of ice with a high content of fine-grained sediments. When a drilling refusal occurred because of a coarser sediment layer (i.e. gravel, blocky material), the ice corer was changed to an 82.5 mm diamond carbide core barrel. The bottom of the ice patches was considered to be attained when the corer extracted large pieces of rock or frozen soil interpreted as the bed of the ice patch. Core#1 was retrieved from ice patch IP1 (83°05'38.39''N; 74°11'58.62'') and core#2 from ice patch IP2 (83°04'54.92''N; 74°04'31.05''). Both cores extended from the surface to the bottom of the ice patches. The core sequence is 319 cm long for core#1 and 249 cm long for core#2. The cores were scanned at the Centre Eau Terre Environnement of the Institut National de la Recherche Scientifique (INRS-ETE), from top to bottom, providing transverse and longitudinal slices images that create a three-dimensional image stack after compilation. The pixel resolution of each horizontal (X) and vertical (Y) image is 0.195 x 0.195 mm giving a two-dimensional pixel resolution of 0.038 mm². Each slice integrates a thickness (Z) of 0.4 mm, making the voxel (volume) resolution of 0.0152 mm³. The output of the scanning is a set of DICOM 16-bit greyscale images. The pixel value, expressed in Hounsfield units (HU), represents the linear attenuation of the X-rays, which depends mainly on the density of the material.

Audrey Veillette (U. Montreal) and Michel Paquette (U. Montreal) helped to collect ice cores in the field. Louis-Frédéric Daigle (INRS-ETE) performed the core scan. Logistical support was provided by Polar Continental Shelf Program (PCSP), Parks Canada and Northern Studies Center (CEN). Financial support was provided by NSERC-ADAPT and NSERC Discovery.

Nordicana D1 - Données des stations climatiques du nord de l'île d'Ellesmere au Nunavut, Canada / Climate station data from Northern Ellesmere Island in Nunavut, Canada

Published

Version 1.0 (1900-1900) - Updated February 12, 2021

Additional information to open CT-scans