Geologic Publications for Mount Rainier

Mount Rainier National Park glacier mass balance monitoring annual report, water year 2011: North Coast and Cascades Network

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

Category: PUBLICATION
Document Type: Natural Resource Data Series NPS/NCCN/NRDS-2015/752
Publisher: National Park Service
Published Year: 2015
Volume:
Number:
Pages: 32
DOI Identifier:
ISBN Identifier:
Keywords:

Abstract:
Glaciers are sensitive indicators of climate change and important drivers of aquatic and terrestrial ecosystems. Glaciers are a high-priority Vital Sign in the North Coast and Cascades Network (NCCN) monitoring plan (Riedel et al. 2008). 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 methods developed as part of the NCCN protocol for Long Term Monitoring of Glaciers at Mount Rainier National Park (Riedel et al., 2010). The purpose of this report is to describe and summarize data collected during the 2011 water year.

Measurement of winter, summer, and net mass balance on Mount Rainier is complicated by steep, often inaccessible ice falls, debris cover, and a 2000 m range in elevation. With the large vertical extent, glacial melt typically begins at the terminus in April and does not begin above 3000 m until 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.

In water year 2011, winter snow accumulation reached a maximum depth of 3.48 m w.e. on Nisqually Glacier and 3.20 m w.e. on Emmons Glacier. Water equivalent (w.e.) values averaged across the entire glacier were 138% of the 2003-2010 average on Nisqually Glacier [+3.28 (±0.77)m w.e.] and 104% of average on Emmons Glacier [+2.35 (±0.46) m w.e.].

Net summer balance on Nisqually Glacier was -2.84 (±1.00) m w.e., and -2.37 (±0.72) m w.e. on Emmons Glacier (81 and 73% of average, respectively). Significant debris cover on the lower portions of both glaciers slowed average ice melt to 41-80% of melt observed on adjacent stakes on clear glacier surfaces.

In 2011, annual net mass balance was positive for Nisqually Glacier [+0.44 (±1.26) m w.e.], the second consecutive positive year. Emmons Glacier had a slight negative balance [-0.02 (±0.85) m w.e.]. Net balances for both glaciers were within the margin of error. Despite the modest increases in glacier balance since 2010, the overall trend in cumulative balance has been strongly negative for both glaciers. Since 2003, the cumulative balance for Nisqually Glacier is -8.61 m w.e. and for Emmons Glacier it is -7.71 m w.e. The cumulative net volume loss in the past eight years is 89.4 million m³ and 58.1 million m³ for Emmons and Nisqually glaciers, respectively.

The equilibrium line altitude was 150 m below average on Emmons Glacier and more than 500 m below average on Nisqually Glacier. The large departure from average for Nisqually glacier was attributed in part to significant snow avalanche debris originating from the upper mountain being deposited at stakes 4 and 4A. This resulted in the deepest snow measured on either glacier in 2011 and the deepest snow measured at these sites in the last 9 years.

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Suggested Citations:
In Text Citation:
Riedel and Larrabee (2015) or (Riedel and Larrabee, 2015)

References Citation:
Riedel, J.L. and M. Larrabee, 2015, Mount Rainier National Park glacier mass balance monitoring annual report, water year 2011: North Coast and Cascades Network: Natural Resource Data Series NPS/NCCN/NRDS-2015/752, National Park Service, 32 p..