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A method for remotely monitoring glaciers with regional application to the Pacific Northwest

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Author(s): Brooke Medley

Document Type: M.S. Thesis
Publisher: Oregon State University
Published Year: 2008
Pages: 85
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An integrative method for monitoring glacier geometry change and mass balance is presented and applied to the Pacific Northwest, USA. Acting as a baseline for interpretation of future changes in glacier size and shape, we first derive a new inventory of regional glacier cover using remotely sensed data. To investigate current climate controls on glacier health, we next model glacier mass balance for select glaciers, incorporating glacier hypsometry results from our new remotely derived inventory. Model results are then used to interpret climate-glacier interactions through sensitivity analysis and the future impacts on glacier geometry. These steps when taken together create a method for remote monitoring of glacier health and dynamics that can be replicated globally.

Inventory results derived from the Advanced Spaceborne Thermal Emission and Reflection Radiometer imagery for the Pacific Northwest indicate that both the North Cascades National Park (99.0 ± 5.0 km2) and the Cascade volcanoes of Washington and Oregon (96.0 ± 4.8 km2) contain similar ice coverage while glaciers of the Olympic Mountains account for only 37.3 ± 1.9 km2. Additionally, significant semi-annual variations in glacier coverage on the Cascade volcanoes highlight the need to consider recent mass balance variations when selecting satellite data for glacier inventorying.

Modeling results provided insight into climate-glacier interactions. Model results from the study glaciers show a recent strengthening of the relationship between summer balance and the El Niño/Southern Oscillation (ENSO) from the mid-1980s to the present. The correlation strengthening between ENSO and summer temperatures around 1985 is manifested in our results through enhanced summer melt. However, the influence of the Pacific Decadal Oscillation (PDO) on balance fluctuations is more ambiguous, as the recent 1976/77 shift into a warm phase is weakly distinguishable at only one study glacier. Glacier sensitivity estimates for a 1° C rise in temperature range from -0.73 to -1.09 mw.e., decreasing with latitude; however, no discernible pattern of precipitation sensitivity exists. At South Cascade glacier, a 30% increase in winter precipitation could offset a 1° C rise in temperature. Glaciers further south require a >40% increase in winter precipitation to remain in balance. However, South Cascade is the only glacier of the four study glaciers that could not exist under a 2° C warming scenario as its accumulation area occupies very low elevations. We postulate that the sensitivity of South Cascade glacier does not change as rapidly as those of the remaining three glaciers as the glacier retreats, making it the most vulnerable to climate change.

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In Text Citation:
Medley (2008) or (Medley, 2008)

References Citation:
Medley, B., 2008, A method for remotely monitoring glaciers with regional application to the Pacific Northwest: M.S. Thesis, Oregon State University, 85 p..