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Climate-related research activities at the Loch Vale WEBB site

Permafrost

In a study of groundwater occurrence and contributions to streamflow in Loch Vale, it was determined that ice stored in permafrost (including rock glaciers) represented the second largest ground water reservoir in the basin [Clow et al., 2003b]. Rock glaciers were mapped and the depth to ice was measured using seismic refraction methods. The extent of potential permafrost was modeled based on remotely-sensed snow cover data and climatic data from the 3 weather stations in Loch Vale. Mean annual air temperatures (MATs) were sufficiently cold to support permafrost above 3460 m (50% of the watershed); however, MATs increased by 2.6°C between 1983 and 2007 [Clow, submitted 2008]. If other climatic factors remain constant, the increase in air temperatures at Loch Vale is sufficient to increase the lower elevational limit of permafrost by approximately 300 m [Clow et al., 2003b; Clow, submitted 2008]. Additional evidence for melting permafrost in Loch Vale is provided by unexpectedly long average transit times for water and sulfur, based on analyses of CFCs, sulfur-35 isotopes, and tritium [Clow et al., 2003a; Clow et al., 2005; Michel et al., 2000].

Earlier research in Loch Vale documented that glaciers contained water approximately equivalent to mean annual runoff for the basin [Ingersoll, 1995]. During drought conditions in 2002-2003, the runoff:precipitation ratio increased from approximately 0.7 to almost 1.0, suggesting that glacier and permafrost melt may have subsidized runoff during late summer [Baron et al., submitted 2008]. Melting glacial ice and permafrost has been implicated as a driving force for increasing nitrate concentrations in streams in Loch Vale [Baron et al., submitted 2008].

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