Surface geophysical data for characterizing shallow, discontinuous frozen ground near Fort Yukon, Alaska
Dates
Publication Date
2020-10-16
Start Date
2012-08-24
End Date
2012-08-30
Citation
Briggs, M.A., White, E.A., and Lane, J.W., 2020, Surface geophysical data for characterizing shallow, discontinuous frozen ground near Fort Yukon, Alaska: U.S. Geological Survey data release, https://doi.org/10.5066/P9UST855.
Summary
The distribution of permafrost in cold regions is subject to temporal and spatial changes influenced by climate, landscape disturbance, and ecosystem succession. Remote sensing from airborne and satellite platforms is increasing our understanding of landscape-scale permafrost distribution, but typically lacks the resolution to characterize finer-scale processes and phenomena, which are often better captured by surface geophysical methods. Specifically, the electrical conductivity of the earth can be used to infer lithological and pore fluid properties, and in this case to delineate frozen, partially frozen, and unfrozen ground. Here, we present electromagnetic induction (EMI) data collected in August 2012 around the highly dynamic [...]
Summary
The distribution of permafrost in cold regions is subject to temporal and spatial changes influenced by climate, landscape disturbance, and ecosystem succession. Remote sensing from airborne and satellite platforms is increasing our understanding of landscape-scale permafrost distribution, but typically lacks the resolution to characterize finer-scale processes and phenomena, which are often better captured by surface geophysical methods. Specifically, the electrical conductivity of the earth can be used to infer lithological and pore fluid properties, and in this case to delineate frozen, partially frozen, and unfrozen ground. Here, we present electromagnetic induction (EMI) data collected in August 2012 around the highly dynamic Twelvemile Lake, Yukon Flats, central Alaska, USA. This data release presents raw and processed results from hand-carried frequency domain EMI data collected with the GEM-2 instrument (Geophex, Ltd.) at approximately 0.75 m off the ground in both vertical and horizontal coplanar modes.
Electromagnetic induction data were used to map variations in subsurface electrical conductivity to infer shallow (approximate upper 5 m of soil) patches of permafrost. The raw instrument quadrature data can be used as a surrogate for bulk soil conductivity, and this raw data can be 'inverted' to recover true depth-specific conductivity values. Only data file 115 was inverted (‘Processed’) here, collected along the upper northwest corner of Twelvemile Lake throughout a mixed shrub and sedge/grass meadow and within the adjacent forest. This area of transiently-dried lakebed is described in these publications: https://doi.org/10.1002/ppp.1893, https://doi.org/10.1002/2014GL059251.
Preview Image
Frequency-Domain Electromagnetic Induction methods near Twelve Mile, AK