Tree-ring-based mass balance reconstruction at Easton Glacier, Washington, USA

Date
2015
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University of Delaware
Abstract
Tree-rings were used to reconstruct a 150-year mass balance record for Easton Glacier in the North Cascades Range of Washington State, USA. An annual ring-width chronology was developed from climate-sensitive Mountain Hemlock trees sampled at high-elevation stands on the south flank of Mount Baker. Dendroclimatic analyses revealed that tree growth was significantly correlated to spring temperature and seasonal snowpack, which provides the basis for the mass balance reconstruction. Linear regression analysis was applied to the ring-width chronology to reconstruct the mass balance history at Easton Glacier and to estimate regional mass balance variations for the period AD 1865-2014. The reconstructions show intervals of positive mass balance between AD 1865 to 1883 and AD 1956 to 1980, and intervals of negative mass balance between AD 1885 to 1895, 1930 to 1950, and the mid 1980s to 2010. The generalized periods of positive and negative mass balance correspond well with known periods of advance and retreat for Easton Glacier, as well as independent proxy records developed for the Pacific Northwest. Our results highlight the influence of the Pacific Decadal Oscillation (PDO) and provide the framework for studies of long-term climate and glacier variability in our study area.
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