Northern Harding Icefield glacier mass balance summary: 2010–2017

Kurtz, Deb

doi:10.36967/2306622

Glaciers cover nearly half of Kenai Fjords National Park, serving an important role in ecosystem dynamics and attracting hundreds of thousands of visitors to the park each year. Glacial melt is important to park managers as it impacts visitor experience, infrastructure (e.g., trails and roads), and downstream habitats. Glacier mass balance is the annual gain and loss of ice calculated as a sum of seasonal measurements of accumulation and ablation (the loss of ice through melt, sublimation, and calving). Long-term glacier mass balance studies provide an established method for monitoring the status of glaciers and can be used to estimate rates of change and to predict thresholds and trigger points that could result in major changes to glacier extent and downstream systems. This report summarizes field efforts and results of eight years of stake-based mass balance measurements on the northern Harding Icefield, for water years 2010–2017. From 2010–2017, seasonal measurements were conducted at six sites on the northern Harding Icefield to quantify seasonal and annual point mass balances along an elevation gradient from 532 m to 1290 m. Cumulative winter mass balances range from 0.47 to 1.81 meters water equivalent (m w.e.) at the lowest site (532 m a.s.l), and 2.11 m w.e. to 3.43 m w.e. at the highest site with continuous annual data (1230 m a.s.l). Summer mass balances range from −5.85 m w.e. to −8.35 m w.e. at the lowest site (532 m a.s.l.) and −0.54 to −2.24 at the site located at 1230 m a.s.l.. Although all sites display interannual variability in the seasonal and annual mass balance, the general trend is of decreasing mass balance. The two sites at the lowest elevations are in the ablation zone and display persistent negative mass balances. The two sites at the middle elevations have been oscillating around a zero or neutral balance and are near the Equilibrium Line Altitude (ELA). The two sites at the highest elevations have positive balances (mass gain) but have shown a decrease over the period of measurements. This has resulted in significant surface melt and elevation loss at lower elevations of Exit Glacier over the period of record.

Northern Harding Icefield glacier mass balance summary: 2010–2017

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