Investigating the Hydrology of the Western Greenland Ice Sheet: Spatiotemporal Variability and Implications on Ice-Dynamics

Since the 1990's the Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate in response to climatic warming and is currently the largest terrestrial contributor to sea-level rise. While ice sheet models agree the GrIS will continue losing mass throughout the century, there are...

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Bibliographic Details
Main Author: Mejia, Jessica Z.
Format: Doctoral or Postdoctoral Thesis
Language:unknown
Published: Digital Commons @ University of South Florida 2021
Subjects:
Online Access:https://digitalcommons.usf.edu/etd/9598
https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=10795&context=etd
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spelling ftunisfloridatam:oai:digitalcommons.usf.edu:etd-10795 2023-05-15T16:28:41+02:00 Investigating the Hydrology of the Western Greenland Ice Sheet: Spatiotemporal Variability and Implications on Ice-Dynamics Mejia, Jessica Z. 2021-04-02T07:00:00Z application/pdf https://digitalcommons.usf.edu/etd/9598 https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=10795&context=etd unknown Digital Commons @ University of South Florida https://digitalcommons.usf.edu/etd/9598 https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=10795&context=etd USF Tampa Graduate Theses and Dissertations Glaciology Moulins Subglacial Lake drainage Climate Geology Geophysics and Seismology dissertation 2021 ftunisfloridatam 2022-11-03T18:46:46Z Since the 1990's the Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate in response to climatic warming and is currently the largest terrestrial contributor to sea-level rise. While ice sheet models agree the GrIS will continue losing mass throughout the century, there are significant uncertainties associated with future sea-level rise contributions. Predicting the GrIS's response to future climate warming scenarios is limited by gaps in our understanding of the links between ice sheet hydrology and dynamics. Meltwater produced on the ice surface flows within supraglacial streams that deliver it to crevasses or moulins—vertical conduits extending from the ice surface to the ice sheet's bed. When the rate of meltwater delivery to moulins exceeds the hydraulic capacity of the moulin-connected subglacial drainage system, meltwater will temporarily backup within moulin shafts, increasing water pressures at the bed which can increase sliding speeds. Despite the central role of moulins in connecting supraglacial and subglacial hydraulic systems, little is known about their role in coupling hydrology and sliding on the GrIS. This dissertation uses several new data sets acquired within the ablation area of Sermeq Avannarleq in the western GrIS to further our understanding of the hydraulic systems that influence sliding within the GrIS ablation area. First, I investigate whether delays in the timing of meltwater delivery for more extensive, higher-elevation catchments could explain the previously progressively later timing of peak daily ice velocity observed with increased elevation and distance from the ice sheet's margin. We measured meltwater delivery to moulins, moulin water level, and the ice velocity response for two moulins at different elevations. Our results show that differences in the timing of meltwater delivery caused peak moulin water level to consistently occur later in the day at our higher-elevation moulin, lagging behind peak pressure at the lower elevation site by 1–3.25 hours. ... Doctoral or Postdoctoral Thesis Greenland Ice Sheet Digital Commons University of South Florida (USF) Greenland Avannarleq ENVELOPE(-49.100,-49.100,62.133,62.133) Sermeq Avannarleq ENVELOPE(-50.833,-50.833,71.033,71.033)
institution Open Polar
collection Digital Commons University of South Florida (USF)
op_collection_id ftunisfloridatam
language unknown
topic Glaciology
Moulins
Subglacial
Lake drainage
Climate
Geology
Geophysics and Seismology
spellingShingle Glaciology
Moulins
Subglacial
Lake drainage
Climate
Geology
Geophysics and Seismology
Mejia, Jessica Z.
Investigating the Hydrology of the Western Greenland Ice Sheet: Spatiotemporal Variability and Implications on Ice-Dynamics
topic_facet Glaciology
Moulins
Subglacial
Lake drainage
Climate
Geology
Geophysics and Seismology
description Since the 1990's the Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate in response to climatic warming and is currently the largest terrestrial contributor to sea-level rise. While ice sheet models agree the GrIS will continue losing mass throughout the century, there are significant uncertainties associated with future sea-level rise contributions. Predicting the GrIS's response to future climate warming scenarios is limited by gaps in our understanding of the links between ice sheet hydrology and dynamics. Meltwater produced on the ice surface flows within supraglacial streams that deliver it to crevasses or moulins—vertical conduits extending from the ice surface to the ice sheet's bed. When the rate of meltwater delivery to moulins exceeds the hydraulic capacity of the moulin-connected subglacial drainage system, meltwater will temporarily backup within moulin shafts, increasing water pressures at the bed which can increase sliding speeds. Despite the central role of moulins in connecting supraglacial and subglacial hydraulic systems, little is known about their role in coupling hydrology and sliding on the GrIS. This dissertation uses several new data sets acquired within the ablation area of Sermeq Avannarleq in the western GrIS to further our understanding of the hydraulic systems that influence sliding within the GrIS ablation area. First, I investigate whether delays in the timing of meltwater delivery for more extensive, higher-elevation catchments could explain the previously progressively later timing of peak daily ice velocity observed with increased elevation and distance from the ice sheet's margin. We measured meltwater delivery to moulins, moulin water level, and the ice velocity response for two moulins at different elevations. Our results show that differences in the timing of meltwater delivery caused peak moulin water level to consistently occur later in the day at our higher-elevation moulin, lagging behind peak pressure at the lower elevation site by 1–3.25 hours. ...
format Doctoral or Postdoctoral Thesis
author Mejia, Jessica Z.
author_facet Mejia, Jessica Z.
author_sort Mejia, Jessica Z.
title Investigating the Hydrology of the Western Greenland Ice Sheet: Spatiotemporal Variability and Implications on Ice-Dynamics
title_short Investigating the Hydrology of the Western Greenland Ice Sheet: Spatiotemporal Variability and Implications on Ice-Dynamics
title_full Investigating the Hydrology of the Western Greenland Ice Sheet: Spatiotemporal Variability and Implications on Ice-Dynamics
title_fullStr Investigating the Hydrology of the Western Greenland Ice Sheet: Spatiotemporal Variability and Implications on Ice-Dynamics
title_full_unstemmed Investigating the Hydrology of the Western Greenland Ice Sheet: Spatiotemporal Variability and Implications on Ice-Dynamics
title_sort investigating the hydrology of the western greenland ice sheet: spatiotemporal variability and implications on ice-dynamics
publisher Digital Commons @ University of South Florida
publishDate 2021
url https://digitalcommons.usf.edu/etd/9598
https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=10795&context=etd
long_lat ENVELOPE(-49.100,-49.100,62.133,62.133)
ENVELOPE(-50.833,-50.833,71.033,71.033)
geographic Greenland
Avannarleq
Sermeq Avannarleq
geographic_facet Greenland
Avannarleq
Sermeq Avannarleq
genre Greenland
Ice Sheet
genre_facet Greenland
Ice Sheet
op_source USF Tampa Graduate Theses and Dissertations
op_relation https://digitalcommons.usf.edu/etd/9598
https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=10795&context=etd
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