Item: Climate change and sierra nevada snowpack
Title: Climate change and sierra nevada snowpack
Proceedings: Proceedings of the 1996 International Snow Science Workshop, Banff, Canada
Authors: Tammy Johnson, Pete Fohl, Jeff Dozier, Tammy Johnson, Department of Geography, University of California, Institute for Computational Earth System Science, University of California, School of Environmental Science and Management, University of Califor
Abstract: Mountainous areas, particularly in the western U.S., provide a large fraction of the fresh water supply. This reserve is possibly vulnerable to changes in climate. Regional precipitation patterns, especially snow, which is a sensitive indicator of change, are predicted to vary with global warming. This study uses a statistical model to link snow water equivalent (SWE) measurements over a 65 year time series to analyze the snow accumulation trends in the Sierra Nevada. We found that snowmelt timing has recently been occurring earlier in the mid-elevations while the maximum amount of seasonal SWE is not changing. However, the monthly snow fraction of the season maximum (snow fraction) are shifting both by month and elevation. Overall, the snow fractions are decreasing, which indicates that snow is accumulating later and melting earlier in the Sierra Nevada. The exceptions are January 1, which is unchanged; low elevations in the early part of the season; and high elevations in mid-season, where the SWE fraction has been increasing. Since values are given for the first of the month, this suggests less snow in January and February, yet more in March, as reflected in the April 1 values. The decrease of SWE fractions on May 1 average to a 23% loss over the last 65 years, while June 1 fractions are down 32%, with greater losses in the higher elevations.
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Keywords: climate change, sierra nevada, snow, historic data, water resources
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