Ice ridge keel size distributions: Analysis of ice ridge keel thickness from Upward Looking Sonar data from the Fram Strait using extreme value theory.
The present thesis explored sea ice ridges in the Fram Strait from data collected at 79 degrees N, 65 degrees W in 2006/2007 by an Upward Looking Sonar instrument, IPS4, and used extreme value analysis to provide an estimate of how deep sea ice ridges could be in this area, and its return period. Ic...
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Online Access: | http://hdl.handle.net/11250/247276 |
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ftntnutrondheimi:oai:ntnuopen.ntnu.no:11250/247276 2023-05-15T15:11:37+02:00 Ice ridge keel size distributions: Analysis of ice ridge keel thickness from Upward Looking Sonar data from the Fram Strait using extreme value theory. Kvadsheim, Synnøve Espy, Patrick Joseph Høyland, Knut Norges teknisk-naturvitenskapelige universitet, Fakultet for naturvitenskap og teknologi, Institutt for fysikk 2014 http://hdl.handle.net/11250/247276 eng eng Institutt for fysikk 730603 ntnudaim:8665 http://hdl.handle.net/11250/247276 74 Master thesis 2014 ftntnutrondheimi 2019-09-17T06:49:16Z The present thesis explored sea ice ridges in the Fram Strait from data collected at 79 degrees N, 65 degrees W in 2006/2007 by an Upward Looking Sonar instrument, IPS4, and used extreme value analysis to provide an estimate of how deep sea ice ridges could be in this area, and its return period. Ice in the Fram Strait originate from different regions in the Arctic Ocean and is therefore representative of the ice ridge distribution in the Arctic.Ice ridges were identified using the Rayleigh method, choosing a threshold value of 2.5 m and a minimum draft value of 5 m.The mean keel draft value was found to be 7.7 m. The shallowest keel observed had a draft of 5.0 m, while the deepest keel was 24.97 m deep. Extreme value analysis was performed on the data collected to find estimates of extreme values of ice ridge keel draft, and its 100-year return level.The shape parameter in the Generalized Pareto distribution was estimated to be close to zero, which qualified for a reduction to the Exponential distribution. The 100-year return level was estimated to be in the range of 37 45 m with the Generalized Pareto distribution and the Exponential distribution. The Weibull distribution was also used in the same analysis, but gave a much lower result with a 100-year return level of 29 m. The fraction of ice observed defined as ice ridges was 3 %. The probability of encountering ice ridges deeper than 20 m was 0.15 m, corresponding to previous results from similar analysis. Master Thesis Arctic Arctic Ocean Fram Strait Sea ice NTNU Open Archive (Norwegian University of Science and Technology) Arctic Arctic Ocean |
institution |
Open Polar |
collection |
NTNU Open Archive (Norwegian University of Science and Technology) |
op_collection_id |
ftntnutrondheimi |
language |
English |
description |
The present thesis explored sea ice ridges in the Fram Strait from data collected at 79 degrees N, 65 degrees W in 2006/2007 by an Upward Looking Sonar instrument, IPS4, and used extreme value analysis to provide an estimate of how deep sea ice ridges could be in this area, and its return period. Ice in the Fram Strait originate from different regions in the Arctic Ocean and is therefore representative of the ice ridge distribution in the Arctic.Ice ridges were identified using the Rayleigh method, choosing a threshold value of 2.5 m and a minimum draft value of 5 m.The mean keel draft value was found to be 7.7 m. The shallowest keel observed had a draft of 5.0 m, while the deepest keel was 24.97 m deep. Extreme value analysis was performed on the data collected to find estimates of extreme values of ice ridge keel draft, and its 100-year return level.The shape parameter in the Generalized Pareto distribution was estimated to be close to zero, which qualified for a reduction to the Exponential distribution. The 100-year return level was estimated to be in the range of 37 45 m with the Generalized Pareto distribution and the Exponential distribution. The Weibull distribution was also used in the same analysis, but gave a much lower result with a 100-year return level of 29 m. The fraction of ice observed defined as ice ridges was 3 %. The probability of encountering ice ridges deeper than 20 m was 0.15 m, corresponding to previous results from similar analysis. |
author2 |
Espy, Patrick Joseph Høyland, Knut Norges teknisk-naturvitenskapelige universitet, Fakultet for naturvitenskap og teknologi, Institutt for fysikk |
format |
Master Thesis |
author |
Kvadsheim, Synnøve |
spellingShingle |
Kvadsheim, Synnøve Ice ridge keel size distributions: Analysis of ice ridge keel thickness from Upward Looking Sonar data from the Fram Strait using extreme value theory. |
author_facet |
Kvadsheim, Synnøve |
author_sort |
Kvadsheim, Synnøve |
title |
Ice ridge keel size distributions: Analysis of ice ridge keel thickness from Upward Looking Sonar data from the Fram Strait using extreme value theory. |
title_short |
Ice ridge keel size distributions: Analysis of ice ridge keel thickness from Upward Looking Sonar data from the Fram Strait using extreme value theory. |
title_full |
Ice ridge keel size distributions: Analysis of ice ridge keel thickness from Upward Looking Sonar data from the Fram Strait using extreme value theory. |
title_fullStr |
Ice ridge keel size distributions: Analysis of ice ridge keel thickness from Upward Looking Sonar data from the Fram Strait using extreme value theory. |
title_full_unstemmed |
Ice ridge keel size distributions: Analysis of ice ridge keel thickness from Upward Looking Sonar data from the Fram Strait using extreme value theory. |
title_sort |
ice ridge keel size distributions: analysis of ice ridge keel thickness from upward looking sonar data from the fram strait using extreme value theory. |
publisher |
Institutt for fysikk |
publishDate |
2014 |
url |
http://hdl.handle.net/11250/247276 |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Fram Strait Sea ice |
genre_facet |
Arctic Arctic Ocean Fram Strait Sea ice |
op_source |
74 |
op_relation |
730603 ntnudaim:8665 http://hdl.handle.net/11250/247276 |
_version_ |
1766342454987980800 |