Reliability analysis for design of stake networks to measure glacier surface velocity
Abstract Measurement of glacier surface velocity provides some constraint on glacier flow models used to date ice cores recovered near the flow divide of remote high-altitude ice caps. The surface velocity is inferred from the change in position of a network of stakes estimated from the least-square...
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Cambridge University Press (CUP)
1999
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Online Access: | http://dx.doi.org/10.1017/s0022143000003130 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000003130 |
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crcambridgeupr:10.1017/s0022143000003130 2024-04-07T07:53:10+00:00 Reliability analysis for design of stake networks to measure glacier surface velocity David Chadwell, C. 1999 http://dx.doi.org/10.1017/s0022143000003130 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000003130 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Journal of Glaciology volume 45, issue 149, page 154-164 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1999 crcambridgeupr https://doi.org/10.1017/s0022143000003130 2024-03-08T00:35:52Z Abstract Measurement of glacier surface velocity provides some constraint on glacier flow models used to date ice cores recovered near the flow divide of remote high-altitude ice caps. The surface velocity is inferred from the change in position of a network of stakes estimated from the least-squares adjustment of geodetic observations – terrestrial and/or spaced-based – collected approximately 1 year apart. The lack of outliers in and the random distribution of the post-fit observation residuals are regarded as evidence that the observations contain no blunders. However, if the network lacks sufficient geometric redundancy, the estimated stake positions can shift to fit erroneous observations. To determine the maximum size of these potential undetected shifts, given the covariance of the observations and the approximate network geometry, expressions are developed to analyze a network for redundancy number and marginally detectable blunders (internal reliability), and the position shifts from marginally detectable blunders (external reliability). Two stake networks, one on the col of Huascar–n (9 ° –07'S, 77 ° –37'W; 6050 m a.s.l.) in the north-central Andes of Peru and one on the Guliya ice cap (35 ° –17'N, 81 ° –29'E; 6200 m a.s.l.) on the Qinghai–Tibetan Plateau in China, are examined for precision and internal and external reliability. Article in Journal/Newspaper Ice cap Journal of Glaciology Cambridge University Press Journal of Glaciology 45 149 154 164 |
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Open Polar |
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Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes David Chadwell, C. Reliability analysis for design of stake networks to measure glacier surface velocity |
topic_facet |
Earth-Surface Processes |
description |
Abstract Measurement of glacier surface velocity provides some constraint on glacier flow models used to date ice cores recovered near the flow divide of remote high-altitude ice caps. The surface velocity is inferred from the change in position of a network of stakes estimated from the least-squares adjustment of geodetic observations – terrestrial and/or spaced-based – collected approximately 1 year apart. The lack of outliers in and the random distribution of the post-fit observation residuals are regarded as evidence that the observations contain no blunders. However, if the network lacks sufficient geometric redundancy, the estimated stake positions can shift to fit erroneous observations. To determine the maximum size of these potential undetected shifts, given the covariance of the observations and the approximate network geometry, expressions are developed to analyze a network for redundancy number and marginally detectable blunders (internal reliability), and the position shifts from marginally detectable blunders (external reliability). Two stake networks, one on the col of Huascar–n (9 ° –07'S, 77 ° –37'W; 6050 m a.s.l.) in the north-central Andes of Peru and one on the Guliya ice cap (35 ° –17'N, 81 ° –29'E; 6200 m a.s.l.) on the Qinghai–Tibetan Plateau in China, are examined for precision and internal and external reliability. |
format |
Article in Journal/Newspaper |
author |
David Chadwell, C. |
author_facet |
David Chadwell, C. |
author_sort |
David Chadwell, C. |
title |
Reliability analysis for design of stake networks to measure glacier surface velocity |
title_short |
Reliability analysis for design of stake networks to measure glacier surface velocity |
title_full |
Reliability analysis for design of stake networks to measure glacier surface velocity |
title_fullStr |
Reliability analysis for design of stake networks to measure glacier surface velocity |
title_full_unstemmed |
Reliability analysis for design of stake networks to measure glacier surface velocity |
title_sort |
reliability analysis for design of stake networks to measure glacier surface velocity |
publisher |
Cambridge University Press (CUP) |
publishDate |
1999 |
url |
http://dx.doi.org/10.1017/s0022143000003130 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000003130 |
genre |
Ice cap Journal of Glaciology |
genre_facet |
Ice cap Journal of Glaciology |
op_source |
Journal of Glaciology volume 45, issue 149, page 154-164 ISSN 0022-1430 1727-5652 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0022143000003130 |
container_title |
Journal of Glaciology |
container_volume |
45 |
container_issue |
149 |
container_start_page |
154 |
op_container_end_page |
164 |
_version_ |
1795668805055152128 |