Monica Palmer

Date of Award

2011

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Earth Sciences

Advisor

Gordon S. Hamilton

Second Committee Member

Cynthia S. Loftin

Third Committee Member

Steven A. Arcone

Abstract

The mass balance of an ice sheet is the difference between mass input from snowfall and mass output from ice flow, blowing snow near the coast, and sublimation. Current estimates for the mass balance of the Antarctic ice sheet have large errors, making it difficult to quantify its contribution to sea-level rise. Most of the error in current estimates arises from a lack of detailed accumulation rate data which is difficult to measure remotely. Accumulation rates vary across small distances, complicating extrapolation of point data, such as ice cores, to regional averages. The size of the ice sheet further complicates collection of widespread ground measurements. Here, we describe a new method for extracting high-resolution accumulation rates from radar profiles, and conduct an analysis of the data. Our method is based on extensive datasets collected during recent overland traverses of the East Antarctic Ice Sheet. These datasets consist of ground-penetrating radar (GPR) profiles, firn/ice cores, and global-positioning system (GPS) data. All three sets of observations are combined to extract high-resolution accumulation rates along traverse routes. This method is effect at capturing small-scale spatial variability in snow distribution over different time periods which provides an opportunity to investigate both spatial and temporal variability in snowfall. The high spatial resolution and long temporal coverage of the data also enable investigation into the effects of topography, climate, and ice advection on accumulation rate distribution. A comparison between our accumulation rate dataset and three widely-used compilations reveals that the large-scale continental compilations perform well over large distances (> 100 km) but do not capture the small scale variability (<10 km) that may account for much of the error in current mass input estimates. We argue that our high-resolution accumulation rate estimates have the potential to greatly improve mass balance estimates compared to the continental scale datasets. This research presents a new method for deriving high-resolution accumulation rates that can be used to better describe the variability of snow distribution across Antarctica in an effort to better understand the ice sheet's current contribution to sea level rise.

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