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Mount Rainier National Park glacier mass balance monitoring annual report, water year 2009: North Coast and Cascades Network

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Author(s): Jon L. Riedel, Michael Larrabee

Document Type: Natural Resource Technical Report NPS/NCCN/NRTR-2011/484
Publisher: National Park Service
Published Year: 2011
Pages: 23
DOI Identifier:
ISBN Identifier:

Glaciers are excellent indicators of climate change and important drivers of aquatic and terrestrial ecosystems. There are currently 27 major glaciers at Mount Rainier National Park, which cover about 90 km2. Since 2003, we have monitored the seasonal mass balance changes of two of these glaciers, Emmons (11.6 km2) and Nisqually (6.9 km2), using six measurement points per glacier. The purpose of this report is to describe and summarize data collected during the 2009 water year.

Measurement of winter, summer, and net mass balance on Mount Rainier is complicated by steep (inaccessible) ice falls, debris cover, and a 2000m range in elevation. With the large vertical extent, glacial melt begins at the terminus in early April and above 3000 m in July. Maximum accumulation occurs between about 2000 and 2500 m elevation, with significant redistribution of snow by wind from southwest to northeast at higher elevations.

Winter snow accumulation reached a maximum depth of 5.2 ±0.4 m on Nisqually Glacier and 3.6 ±0.8 m on Emmons Glacier in water year 2009. Water equivalent (w.e.) values averaged across the entire glacier are near the 2003-2008 winter balance average on Nisqually Glacier (+2.2 m w.e.) and 65 percent of average on Emmons Glacier (+1.46 m w.e.).

Maximum summer melt reached -9.9 m at stake 4 on lower Emmons Glacier in late September. Net summer balance averaged across the measurement sites on Emmons Glacier was -3.79 ±0.75 m w.e., and -3.26 ±0.58 m w.e. on Nisqually Glacier. Significant debris cover on the lower portions of both glaciers slowed average ice melt to 65-80 percent of melt observed on adjacent stakes on clear glacier surfaces.

In 2009, annual net mass balance was negative for the seventh consecutive water year on Emmons Glacier (-1.8 ±0.75 m w.e.) and Nisqually Glacier (-1.64 ±0.58 m w.e.), which continued a long-term trend of declining volume for both glaciers. Since water year 2003, Emmons and Nisqually Glaciers have shown a cumulative net balance of -7.82 and -9.55 m w.e., respectively. Multiplying these two values by the area of each glacier provides an estimated glacial-loss by volume since 2003 of 91M m3 at Emmons and 66 M m3 at Nisqually. This represents an estimate volume loss of about 14% and 31% at Emmons and Nisqually Glaciers.

We estimated that glaciers in the Nisqually and White River watersheds contributed 146 M m3 (37.4 B gallons) of melt water between May 1 and September 30, comprising between 15-20 percent of the total runoff in these basins. This estimate includes snow, glacial ice, and firn.

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Suggested Citations:
In Text Citation:
Riedel and Larrabee (2011) or (Riedel and Larrabee, 2011)

References Citation:
Riedel, J.L. and M. Larrabee, 2011, Mount Rainier National Park glacier mass balance monitoring annual report, water year 2009: North Coast and Cascades Network: Natural Resource Technical Report NPS/NCCN/NRTR-2011/484, National Park Service, 23 p..