The Greenland Ice Sheet: Reconstruction under Modern-Day Conditions and Sensitivity to the North Atlantic Oscillation

• Main Author: Pingree, Katherine A.
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2010
• Subjects: Climatic changes; North Atlantic oscillation; Greenland Ice Sheet; Climate; Earth Sciences; Glaciology; Greenland; Ice Sheet; North Atlantic
• Online Access: https://digitalcommons.library.umaine.edu/etd/743; https://digitalcommons.library.umaine.edu/context/etd/article/1744/viewcontent/PingreeKA2010.pdf

The Greenland Ice Sheet, the sole remaining ice sheet in the Northern Hemisphere, is currently undergoing dynamic changes that have resulted in increasing mass loss. Representing 6-7 m of sea level equivalence, the Greenland Ice Sheet is of great interest to both the scientific community and society. Atmospheric variations are a major controlling aspect of continental glaciations and the health of ice sheets. The Greenland Ice Sheet is particularly exposed to the North Atlantic Oscillation (NAO), a well-known atmospheric fluctuation in sea level pressure between the Icelandic Low and Bermuda-Azores High. Persistence of a single phase of the NAO is known to cause significant changes in mass balance trends over the Greenland Ice Sheet that result in similar changes to the ice sheet. Quantitative estimates of these changes in ice thickness and volume, however, are lacking. NAO is chosen as a characteristic climate driver because it is an identifiable major modern atmospheric oscillation influencing temperature and precipitation over Greenland and may aid in predicting the future response of the Greenland Ice Sheet as well as improving the interpretation of its past. To investigate the Greenland Ice Sheet’s sensitivity to the NAO, numerical ice sheet modeling is utilized. The University of Maine Ice Sheet Model (UMISM) is used to develop a reconstruction of the present-day Greenland Ice Sheet driven primarily with modern-day atmospheric conditions and positive-degree-day mass balance calculations. These mass balance conditions and reconstructed ice sheet are then used to investigate the Greenland Ice Sheet’s sensitivity to persistent NAO phase conditions. Average surface temperature and total precipitation data from six distinctive years in the NAO record are used to drive persistent positive and negative NAO phase UMISM model runs. Comparisons to the reference mass balance conditions and ice sheet identify the resulting changes to the ice sheet (ice thickness and volume). Model runs are compared at temporally ...