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Open Access Thesis

Abstract

Anthropogenic disturbance and global warming are enhancing the influx of freshwater into the oceans from melting glaciers and ice sheets. The Greenland Ice Sheet (GrIS) has experienced accelerated surface melt which is expected to reduce North Atlantic Deep Water (NADW) formation and Atlantic thermohaline circulation. More than half of the GrIS total mass loss is due to meltwater runoff produced on the surface by supraglacial lakes, streams, and rivers. The goal of this study is to monitor changes in supraglacial drainage systems developed in the Southwest region on the GrIS for the 2009-2017 melt seasons and to map the impact of melting glaciers and ice sheets on the nearby ocean salinity for the available 2011-2017 images. A change detection analysis was first conducted using four types of very high-resolution WorldView (WV) satellite imagery. This included 3 WV1, 2 WV2, and 1 WV3 panchromatic images with spatial resolutions of 0.5, 0.46, and 0.31 meters, respectively, as well as 3 WV2 and 2 WV3 multispectral images with spatial resolutions of .85 meters and 1.65 meters, respectively. To map the seasonal changes of supraglacial streams, a modified normalized difference water index (NDWI ice) was used on multispectral images to discern supraglacial water features from bare ice. Then, an object-oriented classification was used to classify objects as supraglacial water features over all WV images in which area changes were compared to assess total surface change of the identified features on the GrIS. Next, meltwater discharge in a delineated catchment was estimated using the regional atmosphere model Modèle Atmosphérique Régional (MAR) and verified with automatic weather station (AWS) data. Finally, sea surface salinity (SSS) changes from Soil Moisture and Ocean Salinity Mission (SMOS) were mapped to show how melting glaciers and icesheets affect ocean salinity. The results of the classification revealed moderate yearly changes in area for the classes identified. Lake area stayed under 0.22% of the catchment area for the study period and river varied between 0.24% to 3.73% of the catchment area. Most years, ice stayed under 1% of the catchment area, except July 2016 where it reached about 7.69% of the catchment area. Slush area ranged between 0.013% and 41.30% of the catchment area. Lake appears to be stable overall, while river had a slight decrease over time. Ice displayed a gradual increase over time, but slush displayed the biggest change with a very noticeable downward trend over the study period. Overall, supraglacial drainage systems showed moderate increases in area over time, with slush showing the largest negative variability in area during the study period. The values of AWS modeled melt (𝑀 mod), MAR melt energy (ME), and MAR runoff (RU) all appear to be increasing over time while surface mass balance (SMB) appeared to be decreasing over time. The observed average change in AWS 𝑀 mod was 2.9%. The observed average change in RU was 12%, SMB was 12.6%, and ME was 9.45% for the study period. This research observed a decreasing trend in SSS during the months following the peak melt for the study period. The observed average change in SSS for July was -0.83%. The observed average change in SSS for August was 0.04%. A decreasing average of 0.36% was observed in SSS over the study period. This research improves the understanding of the GrIS response and development, ocean response to meltwater inputs, and provides reliable estimates of the effects of rising temperatures on the GrIS.

Year of Submission

2026

Degree Name

Master of Arts

Department

Department of Geography

First Advisor

Bingqing Liang

Date Original

2026

Object Description

1 PDF file (xiv, 158 pages)

Language

en

File Format

application/pdf

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