Ice island deterioration

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Creator: 

Crawford, Anna Jean

Date: 

2018

Abstract: 

Ice islands are large, tabular icebergs that calve from ice shelves and floating ice tongues. Their drift and deterioration is of concern to offshore industry and influences the dispersal of freshwater from Earth's major ice sheets. However, the analysis and modelling of ice island deterioration is constrained by a lack of systematic studies using field and remotely sensed data.

The aim of this thesis is to improve our understanding of ice island deterioration through the use and development of novel techniques and datasets. It uses complementary field and remotely sensed datasets in three studies that individually focus on vertical deterioration (i.e., thinning), small-scale areal deterioration (e.g., wave erosion), and large-scale areal deterioration (i.e., fracture). The study subjects are ice islands in eastern Canadian waters that calved from the Petermann Glacier of northwest Greenland between 2008 and 2012.

The vertical deterioration of a grounded Petermann ice island (PII) was quantified with stationary ice penetrating radar (IPR), mobile IPR and ablation stake data measurements collected over three field campaigns. Derived basal ablation was used to calibrate a basal ablation model, which was applied in a separate study to quantify the spatial distribution of meltwater from the drift and deterioration of hundreds of PIIs. This study used the Canadian Ice Island Drift, Deterioration and Detection Database, which was generated through the analysis of thousands of RADARSAT-2 synthetic aperture radar scenes. The database was also used to evaluate the fit of statistical distributions to the size-frequency distributions of PIIs. The results indicate that fracture remained an influential deterioration process over the monitoring period. A third study found that deterioration on the order of 40 cm could be detected under optimal conditions with aerial photogrammetry with structure-from-motion processing and that this technique was superior to laser scanning.

This thesis presents new insights into ice island deterioration processes. It also documents new techniques for measuring deterioration and contributes pertinent information to two major ice island research themes (i.e., hazards and freshwater vectors). Finally, many results and future research directions are applicable to ice island research conducted in both Polar Regions on planet Earth.

Subject: 

Physical Geography

Language: 

English

Publisher: 

Carleton University

Contributor: 

co-author, supervisor: 
Derek Mueller
co-author: 
Gabriel Joyal

Thesis Degree Name: 

Doctor of Philosophy: 
Ph.D.

Thesis Degree Level: 

Doctoral

Thesis Degree Discipline: 

Geography

Parent Collection: 

Theses and Dissertations

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