From the Subglacial Environment to the Coastal Ocean: Exploring Feedbacks Between Glacial Meltwater and Tidewater Glacier Dynamics.
Mass loss from the Antarctic and Greenland ice sheets has accelerated in recent decades and is predicted to contribute < 40 cm of mean sea level rise in the 21st Century. However, there is significant uncertainty in projections of ice sheet mass balance arising from unknowns in the dynamic respon...
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ftunivoregonsb:oai:scholarsbank.uoregon.edu:1794/28089 2023-05-15T14:12:39+02:00 From the Subglacial Environment to the Coastal Ocean: Exploring Feedbacks Between Glacial Meltwater and Tidewater Glacier Dynamics. Hager, Alexander Sutherland, David 2023-03-24 application/pdf https://scholarsbank.uoregon.edu/xmlui/handle/1794/28089 en_US eng University of Oregon https://scholarsbank.uoregon.edu/xmlui/handle/1794/28089 All Rights Reserved. Alaska Antarctica Glacial Fjords Greenland Ice-ocean Interactions Tidewater Glaciers Electronic Thesis or Dissertation 2023 ftunivoregonsb 2023-03-26T16:18:16Z Mass loss from the Antarctic and Greenland ice sheets has accelerated in recent decades and is predicted to contribute < 40 cm of mean sea level rise in the 21st Century. However, there is significant uncertainty in projections of ice sheet mass balance arising from unknowns in the dynamic response of tidewater glaciers to ocean forcing. At both the ice-ocean and ice-bed boundaries, glacial meltwater plays a vital role in governing the dynamics of tidewater glaciers, yet many meltwater processes are difficult to observe and are subsequently parameterized with unvalidated approximations in ice sheet models. Here, I employ a suite of numerical modeling experiments and observations to investigate how glacial meltwater at the bed and in the ocean affects the susceptibility of tidewater glaciers in Antarctica, Alaska, and Greenland to enhanced ocean forcing. It has historically been assumed that the formation of channelized subglacial drainage beneath Antarctic ice sheets is not possible, leading to the use of simplifying parameterizations of subglacial drainage under Antarctic ice sheets. However, recent observations have suggested subglacial channels exist beneath some Antarctic tidewater glaciers and could have a substantial impact on ice shelf ablation and glacier dynamics. In Chapter II, I pair numerical modeling experiments with observed radar specularity content from Thwaites Glacier, West Antarctica, to demonstrate that enough basal meltwater exists to form subglacial channels, which increase frontal ablation and basal friction beneath Thwaites Glacier. In Chapter III and IV, I transition to investigating the impact of glacial meltwater on glacial fjord dynamics. Leveraging numerical modeling with hydrographic observations from LeConte Bay, Alaska, I show that the sill-driven mixing and buoyancy forcing of subglacial discharge drives strong seasonal circulation regimes in LeConte Bay and may impede ice sheet models from accurately parameterizing ocean thermal forcing of tidewater glaciers. I then run ... Thesis Antarc* Antarctic Antarctica glacier glacier glaciers Greenland Ice Sheet Ice Shelf Thwaites Glacier Tidewater West Antarctica Alaska University of Oregon Scholars' Bank Antarctic Greenland The Antarctic Thwaites Glacier ENVELOPE(-106.750,-106.750,-75.500,-75.500) West Antarctica |
institution |
Open Polar |
collection |
University of Oregon Scholars' Bank |
op_collection_id |
ftunivoregonsb |
language |
English |
topic |
Alaska Antarctica Glacial Fjords Greenland Ice-ocean Interactions Tidewater Glaciers |
spellingShingle |
Alaska Antarctica Glacial Fjords Greenland Ice-ocean Interactions Tidewater Glaciers Hager, Alexander From the Subglacial Environment to the Coastal Ocean: Exploring Feedbacks Between Glacial Meltwater and Tidewater Glacier Dynamics. |
topic_facet |
Alaska Antarctica Glacial Fjords Greenland Ice-ocean Interactions Tidewater Glaciers |
description |
Mass loss from the Antarctic and Greenland ice sheets has accelerated in recent decades and is predicted to contribute < 40 cm of mean sea level rise in the 21st Century. However, there is significant uncertainty in projections of ice sheet mass balance arising from unknowns in the dynamic response of tidewater glaciers to ocean forcing. At both the ice-ocean and ice-bed boundaries, glacial meltwater plays a vital role in governing the dynamics of tidewater glaciers, yet many meltwater processes are difficult to observe and are subsequently parameterized with unvalidated approximations in ice sheet models. Here, I employ a suite of numerical modeling experiments and observations to investigate how glacial meltwater at the bed and in the ocean affects the susceptibility of tidewater glaciers in Antarctica, Alaska, and Greenland to enhanced ocean forcing. It has historically been assumed that the formation of channelized subglacial drainage beneath Antarctic ice sheets is not possible, leading to the use of simplifying parameterizations of subglacial drainage under Antarctic ice sheets. However, recent observations have suggested subglacial channels exist beneath some Antarctic tidewater glaciers and could have a substantial impact on ice shelf ablation and glacier dynamics. In Chapter II, I pair numerical modeling experiments with observed radar specularity content from Thwaites Glacier, West Antarctica, to demonstrate that enough basal meltwater exists to form subglacial channels, which increase frontal ablation and basal friction beneath Thwaites Glacier. In Chapter III and IV, I transition to investigating the impact of glacial meltwater on glacial fjord dynamics. Leveraging numerical modeling with hydrographic observations from LeConte Bay, Alaska, I show that the sill-driven mixing and buoyancy forcing of subglacial discharge drives strong seasonal circulation regimes in LeConte Bay and may impede ice sheet models from accurately parameterizing ocean thermal forcing of tidewater glaciers. I then run ... |
author2 |
Sutherland, David |
format |
Thesis |
author |
Hager, Alexander |
author_facet |
Hager, Alexander |
author_sort |
Hager, Alexander |
title |
From the Subglacial Environment to the Coastal Ocean: Exploring Feedbacks Between Glacial Meltwater and Tidewater Glacier Dynamics. |
title_short |
From the Subglacial Environment to the Coastal Ocean: Exploring Feedbacks Between Glacial Meltwater and Tidewater Glacier Dynamics. |
title_full |
From the Subglacial Environment to the Coastal Ocean: Exploring Feedbacks Between Glacial Meltwater and Tidewater Glacier Dynamics. |
title_fullStr |
From the Subglacial Environment to the Coastal Ocean: Exploring Feedbacks Between Glacial Meltwater and Tidewater Glacier Dynamics. |
title_full_unstemmed |
From the Subglacial Environment to the Coastal Ocean: Exploring Feedbacks Between Glacial Meltwater and Tidewater Glacier Dynamics. |
title_sort |
from the subglacial environment to the coastal ocean: exploring feedbacks between glacial meltwater and tidewater glacier dynamics. |
publisher |
University of Oregon |
publishDate |
2023 |
url |
https://scholarsbank.uoregon.edu/xmlui/handle/1794/28089 |
long_lat |
ENVELOPE(-106.750,-106.750,-75.500,-75.500) |
geographic |
Antarctic Greenland The Antarctic Thwaites Glacier West Antarctica |
geographic_facet |
Antarctic Greenland The Antarctic Thwaites Glacier West Antarctica |
genre |
Antarc* Antarctic Antarctica glacier glacier glaciers Greenland Ice Sheet Ice Shelf Thwaites Glacier Tidewater West Antarctica Alaska |
genre_facet |
Antarc* Antarctic Antarctica glacier glacier glaciers Greenland Ice Sheet Ice Shelf Thwaites Glacier Tidewater West Antarctica Alaska |
op_relation |
https://scholarsbank.uoregon.edu/xmlui/handle/1794/28089 |
op_rights |
All Rights Reserved. |
_version_ |
1766284986467483648 |