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Scientific Investigations Report 2010–5247

Re-analysis of Alaskan Benchmark Glacier Mass-Balance Data Using the Index Method

By Ashley E. Van Beusekom, Shad R. O’Neel, Rod S. March, Louis C. Sass, and Leif H. Cox

ABSTRACT

At Gulkana and Wolverine Glaciers, designated the Alaskan benchmark glaciers, we re-analyzed and re-computed the mass balance time series from 1966 to 2009 to accomplish our goal of making more robust time series. Each glacier’s data record was analyzed with the same methods. For surface processes, we estimated missing information with an improved degree-day model. Degree-day models predict ablation from the sum of daily mean temperatures and an empirical degree-day factor. We modernized the traditional degree-day model and derived new degree-day factors in an effort to match the balance time series more closely. We estimated missing yearly-site data with a new balance gradient method. These efforts showed that an additional step needed to be taken at Wolverine Glacier to adjust for non-representative index sites.

As with the previously calculated mass balances, the re-analyzed balances showed a continuing trend of mass loss. We noted that the time series, and thus our estimate of the cumulative mass loss over the period of record, was very sensitive to the data input, and suggest the need to add data-collection sites and modernize our weather stations.

First December 15, 2010

For additional information contact:
Director, Alaska Science Center
U.S. Geological Survey
4210 University Drive
Anchorage, Alaska 99508
http://alaska.usgs.gov

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Suggested citation:

Van Beusekom, A.E., O'Neel, S.R., March, R.S., Sass, L.C., and Cox, L.H., 2010, Re-analysis of Alaskan benchmark glacier mass-balance data using the index method: U.S. Geological Survey Scientific Investigations Report 2010–5247, 16 p.



Contents

Abstract

Introduction

Study Methods

Results of Data Analysis

Conclusions

References Cited

Appendix A. Description of Input and Output Data


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