Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements
The current need for forecasting Greenland Ice Sheet contributions to global sea level rise is complicated by the lack of understanding of ice sheet hydrology. The proportion of meltwater contributing to sea level rise, as well as the pathways transporting meltwater on, through, and out of the ice s...
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ftcdlib:qt4fs5m1qf 2023-05-15T16:25:24+02:00 Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements Chu, Vena 238 2015-01-01 application/pdf http://www.escholarship.org/uc/item/4fs5m1qf http://n2t.net/ark:/13030/m5379hkz en eng eScholarship, University of California http://www.escholarship.org/uc/item/4fs5m1qf qt4fs5m1qf http://n2t.net/ark:/13030/m5379hkz public Chu, Vena. (2015). Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements. UCLA: Geography 0396. Retrieved from: http://www.escholarship.org/uc/item/4fs5m1qf Hydrologic sciences Remote sensing Geographic information science and geodesy Cryosphere Greenland dissertation 2015 ftcdlib 2016-04-02T19:17:04Z The current need for forecasting Greenland Ice Sheet contributions to global sea level rise is complicated by the lack of understanding of ice sheet hydrology. The proportion of meltwater contributing to sea level rise, as well as the pathways transporting meltwater on, through, and out of the ice sheet, are not well understood. Remote sensing of hydrologic dynamics in combination with small-scale fieldwork allows examination of broad spatial and temporal trends in the Greenland hydrologic system responding to a changing climate. This dissertation reviews the current state of knowledge on Greenland Ice Sheet hydrology, and examines three components of the Greenland hydrologic system: (1) fjord sediment plumes as an indicator of meltwater output, (2) supraglacial streamflow as an indicator of meltwater input to the ice sheet, and (3) moulin distribution and formation as a mechanism diverting meltwater from the surface of the ice sheet to the bed. Buoyant sediment plumes that develop in fjords downstream of outlet glaciers are controlled by numerous factors, including meltwater runoff. MODIS retrievals of sediment plume concentration show a strong regional and seasonal response to meltwater production on the ice sheet surface, despite limitations in fjords with rapidly calving glaciers, providing a tool for tracking meltwater release to the ocean. Summertime field observations and high-resolution satellite imagery reveal extensive supraglacial river networks across the southwestern ablation zone transporting large volumes of meltwater to moulins, yet these features remain poorly mapped and their discharges unquantified. A GIS modeling framework is developed to spatially adapt Manning’s equation for use with high-resolution WorldView-2 imagery to map supraglacial river discharge. Moulins represent connections between surface meltwater on the Greenland ice sheet and subglacial drainage networks, where increased meltwater can enhance ice sliding dynamics. A new high-resolution moulin dataset in western Greenland created from WorldView-1/2 imagery in the 2012 record melt year is used to assess moulin distribution and formation. Moulin locations show a significantly different distribution compared to geospatial variables in the entire study area, with moulins forming in areas of thinner ice, higher velocity and extensional strain rate, as well as lower surface elevation and slope, and higher bed elevation and slope. Doctoral or Postdoctoral Thesis Greenland Ice Sheet University of California: eScholarship Greenland |
institution |
Open Polar |
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University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
topic |
Hydrologic sciences Remote sensing Geographic information science and geodesy Cryosphere Greenland |
spellingShingle |
Hydrologic sciences Remote sensing Geographic information science and geodesy Cryosphere Greenland Chu, Vena Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements |
topic_facet |
Hydrologic sciences Remote sensing Geographic information science and geodesy Cryosphere Greenland |
description |
The current need for forecasting Greenland Ice Sheet contributions to global sea level rise is complicated by the lack of understanding of ice sheet hydrology. The proportion of meltwater contributing to sea level rise, as well as the pathways transporting meltwater on, through, and out of the ice sheet, are not well understood. Remote sensing of hydrologic dynamics in combination with small-scale fieldwork allows examination of broad spatial and temporal trends in the Greenland hydrologic system responding to a changing climate. This dissertation reviews the current state of knowledge on Greenland Ice Sheet hydrology, and examines three components of the Greenland hydrologic system: (1) fjord sediment plumes as an indicator of meltwater output, (2) supraglacial streamflow as an indicator of meltwater input to the ice sheet, and (3) moulin distribution and formation as a mechanism diverting meltwater from the surface of the ice sheet to the bed. Buoyant sediment plumes that develop in fjords downstream of outlet glaciers are controlled by numerous factors, including meltwater runoff. MODIS retrievals of sediment plume concentration show a strong regional and seasonal response to meltwater production on the ice sheet surface, despite limitations in fjords with rapidly calving glaciers, providing a tool for tracking meltwater release to the ocean. Summertime field observations and high-resolution satellite imagery reveal extensive supraglacial river networks across the southwestern ablation zone transporting large volumes of meltwater to moulins, yet these features remain poorly mapped and their discharges unquantified. A GIS modeling framework is developed to spatially adapt Manning’s equation for use with high-resolution WorldView-2 imagery to map supraglacial river discharge. Moulins represent connections between surface meltwater on the Greenland ice sheet and subglacial drainage networks, where increased meltwater can enhance ice sliding dynamics. A new high-resolution moulin dataset in western Greenland created from WorldView-1/2 imagery in the 2012 record melt year is used to assess moulin distribution and formation. Moulin locations show a significantly different distribution compared to geospatial variables in the entire study area, with moulins forming in areas of thinner ice, higher velocity and extensional strain rate, as well as lower surface elevation and slope, and higher bed elevation and slope. |
format |
Doctoral or Postdoctoral Thesis |
author |
Chu, Vena |
author_facet |
Chu, Vena |
author_sort |
Chu, Vena |
title |
Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements |
title_short |
Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements |
title_full |
Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements |
title_fullStr |
Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements |
title_full_unstemmed |
Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements |
title_sort |
hydrologic dynamics of the greenland ice sheet from remote sensing and field measurements |
publisher |
eScholarship, University of California |
publishDate |
2015 |
url |
http://www.escholarship.org/uc/item/4fs5m1qf http://n2t.net/ark:/13030/m5379hkz |
op_coverage |
238 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
Chu, Vena. (2015). Hydrologic dynamics of the Greenland Ice Sheet from remote sensing and field measurements. UCLA: Geography 0396. Retrieved from: http://www.escholarship.org/uc/item/4fs5m1qf |
op_relation |
http://www.escholarship.org/uc/item/4fs5m1qf qt4fs5m1qf http://n2t.net/ark:/13030/m5379hkz |
op_rights |
public |
_version_ |
1766014149277515776 |