GLACIER MONITORING IN DENALI NATIONAL PARK AND PRESERVE

Glaciers are a major feature in Denali National Park and Preserve (Denali), covering about 17%, 1 million acres, of the park. Glacier behavior in Denali varies from apparent steady flow glaciers to erratic surge-type glaciers. This variety offers opportunities to study glacier movements dominated by climate as well as those that are influenced by other factors. A formal glacier monitoring program began in Denali in 1991 as part of the National Park Service’s Long-term Ecological Monitoring Program, in cooperation with the US Geological Survey and the Geophysical Institute at the University of Alaska-Fairbanks. The fundamental aspect of the program was an “index” method, or single point mass balance monitoring. That method has been supplemented with more detailed mass balance measurements on a smaller glaciers, terminus monitoring on multiple glaciers, selected movement monitoring, depth measurements, and photo documentation. Protocols for the index method were developed in hopes of extending the use of the method to other park units. The glacier monitoring program also includes

Two index monitoring sites are maintained in Denali, on the Kahiltna and Muldrow glaciers, both sites are at or near the ELA and attempt to measure conditions on the south and north sides of the Alaska Range, respectively. Since monitoring began in 1991, the Kahiltna glacier index site has had a slightly positive mass balance and a variable velocity that ranges from 180 to 250 meters per year. Seasonal balances are on the order of +/- one meter of water equivalency per year. During the same time period, the Traleika glacier has shown a consistently negative mass balance within a slightly narrower range of seasonal balances. Interestingly, the surface altitude of the index site has been increasing steadily despite the period of negative mass balance. This thickening may play a role in the surge-cycle of the Muldrow glacier, to which the Traleika is a major tributary. Since 1991, the Traleika glacier has flowed at a rate between 20 and 70 meters per year. In addition to the methods used and data acquired through the index monitoring program, results will be presented from other components of the glacier monitoring program in Denali.