Estimating ice temperature from short records in thermally disturbed boreholes

Abstract A technique to estimate undisturbed ice temperature is discussed for sensors placed in boreholes that have been heated to the melting point during drilling, and for which only a limited time span of temperature record is available. A short temperature record after the hole refreezes commonl...

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Published in:Journal of Glaciology
Main Author: Humphrey, Neil
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 1991
Subjects:
Online Access:http://dx.doi.org/10.1017/s0022143000005840
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000005840
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spelling crcambridgeupr:10.1017/s0022143000005840 2023-06-11T04:06:28+02:00 Estimating ice temperature from short records in thermally disturbed boreholes Humphrey, Neil 1991 http://dx.doi.org/10.1017/s0022143000005840 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000005840 en eng Cambridge University Press (CUP) Journal of Glaciology volume 37, issue 127, page 414-419 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1991 crcambridgeupr https://doi.org/10.1017/s0022143000005840 2023-05-01T18:21:50Z Abstract A technique to estimate undisturbed ice temperature is discussed for sensors placed in boreholes that have been heated to the melting point during drilling, and for which only a limited time span of temperature record is available. A short temperature record after the hole refreezes commonly results when using hot-water or steam drills, where measurements are constrained by logistics, ice deformation, sensor drift or other problems, or where the refreezing time is long because of near-freezing ice temperatures or large hole sizes. Short data records are also typical in ongoing drilling programs where temperature information may be necessary for the program itself. Building on analyses by Lachenbruch and Brewer (1959) and a numerical model by Jarvis and Clarke (1974), it is shown that estimates of undisturbed temperatures can be made from records of temperature that extend only marginally beyond the initial refreezing. Complex effects of hole size, heating history, and the thermodynamic and geometrical effects of a moving boundary (the freezing borehole walls) are important to temperature decay immediately after freeze-up, so that the standard technique of comparing temperature decay to an inverse of time model is not applicable, and comparsion has to be made to a numerical model of heat flow to a refreezing borehole. Data from Ice Stream B, Antarctica, are compared to the numerical model to illustrate the technique. Data are also compared to simpler (inverse time) thermal models, and a potential for error is pointed out, since a short data record can be spuriously matched with the simpler, one or two free-parameter, models. Article in Journal/Newspaper Antarc* Antarctica Ice Stream B Journal of Glaciology Cambridge University Press (via Crossref) Journal of Glaciology 37 127 414 419
institution Open Polar
collection Cambridge University Press (via Crossref)
op_collection_id crcambridgeupr
language English
topic Earth-Surface Processes
spellingShingle Earth-Surface Processes
Humphrey, Neil
Estimating ice temperature from short records in thermally disturbed boreholes
topic_facet Earth-Surface Processes
description Abstract A technique to estimate undisturbed ice temperature is discussed for sensors placed in boreholes that have been heated to the melting point during drilling, and for which only a limited time span of temperature record is available. A short temperature record after the hole refreezes commonly results when using hot-water or steam drills, where measurements are constrained by logistics, ice deformation, sensor drift or other problems, or where the refreezing time is long because of near-freezing ice temperatures or large hole sizes. Short data records are also typical in ongoing drilling programs where temperature information may be necessary for the program itself. Building on analyses by Lachenbruch and Brewer (1959) and a numerical model by Jarvis and Clarke (1974), it is shown that estimates of undisturbed temperatures can be made from records of temperature that extend only marginally beyond the initial refreezing. Complex effects of hole size, heating history, and the thermodynamic and geometrical effects of a moving boundary (the freezing borehole walls) are important to temperature decay immediately after freeze-up, so that the standard technique of comparing temperature decay to an inverse of time model is not applicable, and comparsion has to be made to a numerical model of heat flow to a refreezing borehole. Data from Ice Stream B, Antarctica, are compared to the numerical model to illustrate the technique. Data are also compared to simpler (inverse time) thermal models, and a potential for error is pointed out, since a short data record can be spuriously matched with the simpler, one or two free-parameter, models.
format Article in Journal/Newspaper
author Humphrey, Neil
author_facet Humphrey, Neil
author_sort Humphrey, Neil
title Estimating ice temperature from short records in thermally disturbed boreholes
title_short Estimating ice temperature from short records in thermally disturbed boreholes
title_full Estimating ice temperature from short records in thermally disturbed boreholes
title_fullStr Estimating ice temperature from short records in thermally disturbed boreholes
title_full_unstemmed Estimating ice temperature from short records in thermally disturbed boreholes
title_sort estimating ice temperature from short records in thermally disturbed boreholes
publisher Cambridge University Press (CUP)
publishDate 1991
url http://dx.doi.org/10.1017/s0022143000005840
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000005840
genre Antarc*
Antarctica
Ice Stream B
Journal of Glaciology
genre_facet Antarc*
Antarctica
Ice Stream B
Journal of Glaciology
op_source Journal of Glaciology
volume 37, issue 127, page 414-419
ISSN 0022-1430 1727-5652
op_doi https://doi.org/10.1017/s0022143000005840
container_title Journal of Glaciology
container_volume 37
container_issue 127
container_start_page 414
op_container_end_page 419
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