Debris properties and mass-balance impacts on adjacent debris-covered glaciers, Mount Rainier, USA

Abstract

The north and east slopes of Mount Rainier, Washington, are host to three of the largest glaciers in the contiguous United States: Carbon Glacier, Winthrop Glacier, and Emmons Glacier. Each has an extensive blanket of supraglacial debris on its terminus, but recent work indicates that each has responded to late twentieth-and early twenty-first-century climate changes in a different way. While Carbon Glacier has thinned and retreated since 1970, Winthrop Glacier has remained steady and Emmons Glacier has thickened and advanced. There are several possible climatic and dynamic factors that can account for some of these disparities, but differences in supraglacial debris properties and distribution have not been systematically evaluated. We combine field measurements and satellite remote sensing analysis from a 10-day period in the 2014 melt season to estimate both the debris thickness distribution and key debris thermal properties on Emmons Glacier. A simplified energy-balance model was then used with debris surface temperatures derived from Landsat 8 thermal infrared bands to estimate the distribution of debris across all three debris-covered termini. The results suggest that differences in summer balance among these glaciers can be partly explained by differences in the thermal resistance of their debris mantles.

Differences in the transient responses of individual glaciers: a case study of the Cascade Mountains of Washington State, USA

“…An important caveat for some of these cases is that several glaciers on Mount Rainier have extensive debris cover, which can lower melt rates (e.g. Moore and others, 2019). While observations do support strongly negative b t , our estimates may be too negative for debris-covered glaciers.…”

Brief communication: A framework to classify glaciers for water resource evaluation and management in the Southern Andes

“…> 2 m) have not been validated, so their effectiveness at differentiating between intermediate and insulated glaciers is unknown. The influence of debris cover on sensitivity could potentially be assessed in a more direct way since a relationship between satellitederived surface temperatures and mass balance has been observed for debris-covered glaciers with debris thicknesses of up to 0.4 m (Moore et al, 2019). Evaluation of the geomorphology and glacier delineation could potentially be completed in an objective way, applying methods used to automatically detect debris-covered glaciers and rock glaciers (Lu et al, 2021;Robson et al, 2020).…”

Brief communication: A framework to classify glaciers for water resource evaluation and management in the Southern Andes

“…Utilizing this logistical regression approach for classification would facilitate the application of this scheme at a regional scale. The influence of debris cover on sensitivity could potentially be assessed in a more direct way since a relationship between satellite-derived surface temperatures and mass balance has been observed for debris-covered glaciers with debris thicknesses up to 0.4 m (Moore et al, 2019). Further investigation is needed to determine if this relationship exists for glaciers with thicker debris cover, and how it may vary along the Andean range.…”