TITLE: Distributed temperature sensing data from a borehole drilled to the base of Sermeq Kujalleq (Store Glacier), Greenland, in July 2019

ASSOCIATED PUBLICATION: Thermodynamics of a fast-moving Greenlandic outlet glacier revealed by fiber-optic distributed temperature sensing

ASSOCIATED PUBLICATION TEASER: Highly resolved observations from a 1,043 m deep borehole show highly variable ice properties and heterogeneous deformation.

ABSTRACT: This is distributed temperature sensing (DTS) data from a 1,043 m borehole drilled to the base of Sermeq Kujalleq (Store Glacier), Greenland, 28 km inland from the glacier terminus. The DTS system was installed on 5 July 2019, with recordings continuing until cable failure on 13 August 2019. The record resolution is ~0.65 m.

KEYWORDS: Greenland, distributed temperature sensing (DTS), ice boreholes, Store Glacier, marine-terminating glacier, ice temperature

PERSONNEL: NAME: Robert Law ROLE: ContactPerson, DataCollector, DataCurator, ProjectMember ORGANISATION: Scott Polar Research Institute, University of Cambridge ORCID: orcid.org/0000-0003-0067-5537

NAME: Poul Christoffersen
ROLE: ProjectLeader, ProjectManager
ORGANISATION: Scott Polar Research Institute, University of Cambridge
ORCID: orcid.org/0000-0003-2643-8724

NAME: Bryn Hubbard
ROLE: ProjectManager 
ORGANISATION: Centre for Glaciology, Aberystwyth University
ORCID: orcid.org/0000-0002-3565-3875

NAME: Samuel Doyle
ROLE: DataCollector, ProjectMember
ORGANISATION: Centre for Glaciology, Aberystwyth University
ORCID: orcid.org/0000-0002-0853-431X

LINEAGE/METHODOLOGY: The data was gathered from Store Glacier, Greenland, in 2019 using a borehole drilling system as described in Doyle et al. (2018) with an additional heater unit. Drilling occured from 4-5 July 2019. The vertical spatial resolution is ~0.65 m, with a sampling resolution of 0.25 m. The measurement averaging time was originally set at 2 minutes with near continuous operation from 5 July to 21 July whereupon it was set to 10 minutes with a rest time of 40 minutes, with the rest time increased to 4 hours on 23rd July to reduce power consumption for unattended operation. This raw instrument-produced data was then processed using the DTS processing package 'dtsalibration' written in Python (des Tombe et al., 2020) with the sampling time increased dependent on usage/figure output (8 hours for image plot of entire record, 96 hours for final plot before failure).

INSTRUMENTATION: The data was collected with a Silixa XT-DTS. The cable was a BRUsens DTS steel-armored cable with 2 single-mode (OS2) fibres and 4 multi-mode (OM3) fibres in a dublex arrangement using a basal turnaround assemblage. The single-mode fibres were used in a seperate distributed acoustic sensing study (Booth et al., 2020). The dtscalibration Python package (v0.9.2) was used to process the data (https://python-dts-calibration.readthedocs.io/ https://pypi.org/project/dtscalibration/ https://github.com/dtscalibration/python-dts-calibration). Data sheets are provided where possible in the data_sheets directory.

QUALITY: The data was calibrated using thermistor data and temperate ice at the phase-transition temperature. 95% confidence intervals are reported in Law et al. (2021) and are provided in this data set, derived from a Monte Carlo simulation. The data was fitted to thermistors, subjectivity in this fitting, and thermistor uncertainty from factors such as ice-bath calibration may further increase unertainty - see Law et al. (2021) for a full discussion.

RELATED URLS: https://www.spri.cam.ac.uk/people/law/ https://www.spri.cam.ac.uk/people/christoffersen/ https://www.erc-responder.eu/

TEMPORAL COVERAGE: 07:45 5 July 2019 - 21:30 13 August 2019.

SPATIAL COVERAGE: 70.57 N, 50.09 W

RESOLUTION: ~0.65 m spatial resolution.

LOCATION: Sermeq Kujalleq (Store Glacier), Uummannaq Fjord, Greenland. Drill site at 70.57 N, 50.09 W.

REFERENCES:

Booth, A. D., Christoffersen, P., Schoonman, C., Clarke, A., Hubbard, B., Law, R., Doyle, S. H., Chudley, T. R., & Chalari, A. (2020). Distributed Acoustic Sensing of Seismic Properties in a Borehole Drilled on a Fast‐Flowing Greenlandic Outlet Glacier. Geophysical Research Letters, 47(13), e2020GL088148. https://doi.org/10.1029/2020GL088148

des Tombe, B., Schilperoort, B., Perkó, Z., Bakker, M., Van De Giesen, N., & Selker, J. (2019). Distributed Temperature Sensing (DTS) calibration with confidence intervals. European Geophysical Union, Geophysical Research Abstracts, 21, 2019–16681. https://doi.org/10.3390/s20082235

Doyle, S. H., Hubbard, B., Christoffersen, P., Young, T. J., Hofstede, C., Bougamont, M., Box, J. E., & Hubbard, A. (2018). Physical Conditions of Fast Glacier Flow: 1. Measurements From Boreholes Drilled to the Bed of Store Glacier, West Greenland. Journal of Geophysical Research: Earth Surface, 123(2), 324–348. https://doi.org/10.1002/2017JF004529

Law, R., Christoffersen, P., Hubbard, B., Doyle, S. H., Chudley, T. R., Schoonman, C., Bougamont, M., des Tombe, B., Schilperoort, B., Kechavarzi, C., Booth, A., & Young, T. J. (2021). Thermodynamics of a fast-moving Greenlandic outlet glacier revealed by fiber-optic distributed temperature sensing. Minor revisions in Science Advances.