The surges of Variegated Glacier and their connection to climate and mass balance

• Main Authors: Eisen, Olaf, Harrison, W. D., Raymond, C. F.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2001
• Subjects: glacier; Journal of Glaciology; Alaska
• Online Access: https://epic.awi.de/id/eprint/4521/; https://epic.awi.de/id/eprint/4521/1/Ola2000b.pdf; https://hdl.handle.net/10013/epic.15096; https://hdl.handle.net/10013/epic.15096.d001

One of the questions still unanswered concerning the surge behavior of glaciersis their quasi-periodic occurrence.Some results on the influence of climate on surges of Variegated Glacier, Alaska, are discussed here.The main emphasis is put on the phenomenological connection between cumulative balance and surge initiation.Based on climate data from a neighboring weather station, a correlation betweenprecipitation, minimum temperature and local annual balance at a location in theaccumulation area is established for the period 1973-82.Additional data from two other weather stations make it possible to reconstructthe local annual balance back to 1905.The ice equivalent local cumulative balance between the last four surges in 1946/47, 1964/65, 1982/83 and 1994/95 is on average 43.5 m, with a1$\sigma$-error of 1.2~m.This surge level provides an explanation for the varying lengths of the surge intervals of Variegated Glacier.The initiation of a surge is determined by the accumulation of mass during the quiescent period prior to the surge, and thus by the average annual mass balancein the previous surge interval.This explanation for the length of the quiescent inverval cannot be directly interpreted in physical terms and the surge level can therefore not beused to explain the observed differences in surge intervals between different glaciers.The surge level is used to hindcast former unobserved surges, to compare the results with other surge datings obtained from photographs, and to establish a complete surge history for Variegated Glacier for the 20th century.