No Cover Image

E-Thesis 276 views 63 downloads

Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet. / Laura Cordero-Llana

Swansea University Author: Laura Cordero-Llana

Abstract

The influence that supra-glacial lakes have had in the recent mass loss at the margins of the Greenland ice sheet has been widely studied. Lakes can drain to the lase of a glacier, lubricating the bed, and enhancing acceleration of the glacier and hence ice thinning. Recent studies suggested that me...

Full description

Published: 2012
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42327
Tags: Add Tag
No Tags, Be the first to tag this record!
first_indexed 2018-08-02T18:54:26Z
last_indexed 2018-08-03T10:09:51Z
id cronfa42327
recordtype RisThesis
fullrecord <?xml version="1.0"?><rfc1807><datestamp>2018-08-02T16:24:28.8541953</datestamp><bib-version>v2</bib-version><id>42327</id><entry>2018-08-02</entry><title>Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet.</title><swanseaauthors><author><sid>3c6832a7d6a7ecbe765de58918325201</sid><ORCID>NULL</ORCID><firstname>Laura</firstname><surname>Cordero-Llana</surname><name>Laura Cordero-Llana</name><active>true</active><ethesisStudent>true</ethesisStudent></author></swanseaauthors><date>2018-08-02</date><abstract>The influence that supra-glacial lakes have had in the recent mass loss at the margins of the Greenland ice sheet has been widely studied. Lakes can drain to the lase of a glacier, lubricating the bed, and enhancing acceleration of the glacier and hence ice thinning. Recent studies suggested that melt extent is not directly linked to the dynamic loss but it has been broken to be linked to peak summer speed ups of the ice sheet front. Large volumes of water are necessary to propagate cracks to the glacial bed via hydrofractures. Hydrological models showed that lakes above a critical volume can supply the necessary water for this process, so the ability to measure water depth in lakes remotely is important to study these processes. The aim of this thesis was to test the current models used for water depth calculations based on the optical properties of water. An optimisation model to estimate water depths was developed. Atmospherically-corrected data from ASTER and MODIS were used as an input to the water reflectance model. As a reference dataset, ICESat measurements were used to obtain lake geometries over empty lakes. Differences between modelled and reference depths are used in a minimisation model to obtain parameters for the water-reflectance model, yielding optimised lake depth estimates. The key contribution of this research was the development of a Monte Carlo simulation. This method allows the quantification of uncertainties in water depth and hence water volume, for the first time. This robust analysis provided better understanding of the sensitivity of the model to the input parameters. There is scope to improve current models of depth estimations if more extensive held observations are done.</abstract><type>E-Thesis</type><journal/><journalNumber></journalNumber><paginationStart/><paginationEnd/><publisher/><placeOfPublication/><isbnPrint/><issnPrint/><issnElectronic/><keywords>Geomorphology.;Remote sensing.;Geophysics.</keywords><publishedDay>31</publishedDay><publishedMonth>12</publishedMonth><publishedYear>2012</publishedYear><publishedDate>2012-12-31</publishedDate><doi/><url/><notes/><college>COLLEGE NANME</college><department>Geography</department><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><degreelevel>Doctoral</degreelevel><degreename>Ph.D</degreename><apcterm/><lastEdited>2018-08-02T16:24:28.8541953</lastEdited><Created>2018-08-02T16:24:28.8541953</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Biosciences, Geography and Physics - Geography</level></path><authors><author><firstname>Laura</firstname><surname>Cordero-Llana</surname><orcid>NULL</orcid><order>1</order></author></authors><documents><document><filename>0042327-02082018162445.pdf</filename><originalFilename>10798035.pdf</originalFilename><uploaded>2018-08-02T16:24:45.7170000</uploaded><type>Output</type><contentLength>26296865</contentLength><contentType>application/pdf</contentType><version>E-Thesis</version><cronfaStatus>true</cronfaStatus><embargoDate>2018-08-02T16:24:45.7170000</embargoDate><copyrightCorrect>false</copyrightCorrect></document></documents><OutputDurs/></rfc1807>
spelling 2018-08-02T16:24:28.8541953 v2 42327 2018-08-02 Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet. 3c6832a7d6a7ecbe765de58918325201 NULL Laura Cordero-Llana Laura Cordero-Llana true true 2018-08-02 The influence that supra-glacial lakes have had in the recent mass loss at the margins of the Greenland ice sheet has been widely studied. Lakes can drain to the lase of a glacier, lubricating the bed, and enhancing acceleration of the glacier and hence ice thinning. Recent studies suggested that melt extent is not directly linked to the dynamic loss but it has been broken to be linked to peak summer speed ups of the ice sheet front. Large volumes of water are necessary to propagate cracks to the glacial bed via hydrofractures. Hydrological models showed that lakes above a critical volume can supply the necessary water for this process, so the ability to measure water depth in lakes remotely is important to study these processes. The aim of this thesis was to test the current models used for water depth calculations based on the optical properties of water. An optimisation model to estimate water depths was developed. Atmospherically-corrected data from ASTER and MODIS were used as an input to the water reflectance model. As a reference dataset, ICESat measurements were used to obtain lake geometries over empty lakes. Differences between modelled and reference depths are used in a minimisation model to obtain parameters for the water-reflectance model, yielding optimised lake depth estimates. The key contribution of this research was the development of a Monte Carlo simulation. This method allows the quantification of uncertainties in water depth and hence water volume, for the first time. This robust analysis provided better understanding of the sensitivity of the model to the input parameters. There is scope to improve current models of depth estimations if more extensive held observations are done. E-Thesis Geomorphology.;Remote sensing.;Geophysics. 31 12 2012 2012-12-31 COLLEGE NANME Geography COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:28.8541953 2018-08-02T16:24:28.8541953 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Geography Laura Cordero-Llana NULL 1 0042327-02082018162445.pdf 10798035.pdf 2018-08-02T16:24:45.7170000 Output 26296865 application/pdf E-Thesis true 2018-08-02T16:24:45.7170000 false
title Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet.
spellingShingle Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet.
Laura Cordero-Llana
title_short Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet.
title_full Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet.
title_fullStr Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet.
title_full_unstemmed Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet.
title_sort Use of remote sensing to assess supra-glacial lake depths on the Greenland Ice Sheet.
author_id_str_mv 3c6832a7d6a7ecbe765de58918325201
author_id_fullname_str_mv 3c6832a7d6a7ecbe765de58918325201_***_Laura Cordero-Llana
author Laura Cordero-Llana
author2 Laura Cordero-Llana
format E-Thesis
publishDate 2012
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Geography{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Geography
document_store_str 1
active_str 0
description The influence that supra-glacial lakes have had in the recent mass loss at the margins of the Greenland ice sheet has been widely studied. Lakes can drain to the lase of a glacier, lubricating the bed, and enhancing acceleration of the glacier and hence ice thinning. Recent studies suggested that melt extent is not directly linked to the dynamic loss but it has been broken to be linked to peak summer speed ups of the ice sheet front. Large volumes of water are necessary to propagate cracks to the glacial bed via hydrofractures. Hydrological models showed that lakes above a critical volume can supply the necessary water for this process, so the ability to measure water depth in lakes remotely is important to study these processes. The aim of this thesis was to test the current models used for water depth calculations based on the optical properties of water. An optimisation model to estimate water depths was developed. Atmospherically-corrected data from ASTER and MODIS were used as an input to the water reflectance model. As a reference dataset, ICESat measurements were used to obtain lake geometries over empty lakes. Differences between modelled and reference depths are used in a minimisation model to obtain parameters for the water-reflectance model, yielding optimised lake depth estimates. The key contribution of this research was the development of a Monte Carlo simulation. This method allows the quantification of uncertainties in water depth and hence water volume, for the first time. This robust analysis provided better understanding of the sensitivity of the model to the input parameters. There is scope to improve current models of depth estimations if more extensive held observations are done.
published_date 2012-12-31T03:52:45Z
_version_ 1763752610569912320
score 11.013148

Similar Items