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Large quantities of organic carbon are stored in frozen soils (permafrost) within Arctic and sub-Arctic regions. A warming climate can induce environmental changes that accelerate the microbial breakdown of organic carbon and the release of the greenhouse gases carbon dioxide and methane. This feedback can accelerate climate change, but the magnitude and timing of greenhouse gas emission from these regions and their impact on climate change remain uncertain. Here we find that current evidence suggests a gradual and prolonged release of greenhouse gas emissions in a warming climate and present a research strategy with which to target poorly understood aspects of permafrost carbon dynamics.
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Abstract: We present an inverse modeling approach for reconstructing the effective thermal conductivity of snow on a daily basis using air temperature, ground temperature and snow depth measurements. The method is applied to four sites in Alaska. To validate the method we used measured snow densities and snow water equivalents. The modeled thermal conductivities of snow for the two interior Alaska sites have relatively low values and reach their maximum near the end of the snow season, while the conductivities at the two sites on the Alaskan North Slope are higher and reach their maximum earlier in the snow season. We show that the reconstructed daily thermal conductivities allow for more accurate modeling of ground...
Categories: Data,
Publication;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Alaska CSC,
Climate and Ecosystem Modeling,
SWE,
Snow thermal conductivity,
Thermal properties, All tags...
inverse modeling,
permafrost,
snow, Fewer tags
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Abstract (from ScienceDirect): Ice wedge polygons on the North Slope of Alaska have been forming for many millennia, when the ground thermally contracts in the winter and water fills in the cracks during the snowmelt season. The infiltrated water then freezes and turns into ice. In this paper we investigate temperature dynamics around the ice wedges and surrounding permafrost. A 2-D nonlinear heat equation with phase change is utilized to compute temperature across the ice wedge and surrounding area. Thermal properties of the ground material are estimated by assimilating temperature measurements in the center of ice wedge polygons. The developed finite element model is successfully validated using two analytical...
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Abstract (from http://www.sciencedirect.com/science/article/pii/S0165232X1400038X#): We present an inverse modeling approach for reconstructing the effective thermal conductivity of snow on a daily basis using air temperature, ground temperature and snow depth measurements. The method is applied to four sites in Alaska. To validate the method we used measured snow densities and snow water equivalents. The modeled thermal conductivities of snow for the two interior Alaska sites have relatively low values and reach their maximum near the end of the snow season, while the conductivities at the two sites on the Alaskan North Slope are higher and reach their maximum earlier in the snow season. We show that the reconstructed...
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