Nichols College Dudley, MA 01571, USA

Glaciological and Arctic Sciences Institute, University of Idaho, Moscow ID 83843, USA

Denali National Park and Preserve, P.O. Box 9, Denali Park, AK 99755, USA

Geography Program, University of Northern British Columbia, 3333 University Way, Prince George, B.C. V2L 2R4, Canada

Glaciological and Arctic Sciences Institute, University of Idaho, Moscow ID 83843, USA

Glaciological and Arctic Sciences Institute, University of Idaho, Moscow ID 83843, USA

Institute of Geodesy, Universitat der Bundeswehr, Werner Heisenberg Weg, 85577 Neubiberg, Germany