NSIDC Cryosphere Seminar
Estimating permafrost thickness in the Yukon-Kuskokwim Delta using LIDAR with Dr. Kevin Schaefer
Abstract: The thickness of the permafrost layer remains difficult to measure, yet is a key parameter on the status of permafrost. The Yukon-Kuskokwim Delta region in southwest Alaska consists of raised peat plateaus separated by sunken thermokarst gulleys and wetlands. Permafrost forms under the peat plateaus, causing them to heave up. Permafrost does not occur in the sunken thermokarst gulleys and wetlands. Because soil expands when frozen, the height of the peat plateaus relative to the sunken wetlands represents a measure of the thickness of the permafrost layer under the peat. We use LIDAR measurements of surface height from IceSat-2 to measure the height of individual peat plateaus. We then use the frozen soil expansion model from the Remotely Sensed Active Layer Thickness (ReSALT) algorithm to estimate permafrost thickness. We correlate the results with Active Layer Thickness (ALT) and soil moisture measured using L-band and P-band Synthetic Aperture Radar (SAR, both satellite and airborne, collected as part of NASA’s Arctic Boreal Vulnerability Experiment (ABoVE). Preliminary results indicate the height of the peat plateaus vary from 2-6 meters above the wetlands, indicating permafrost extends down to depths of 50-150 meters.
Bio: Kevin Schaefer is a senior research scientist studying permafrost dynamics using modeling, remote sensing, and in situmeasurements. Dr. Schaefer received an engineering degree in 1984 and worked for NASA on the Space Shuttle and Space Station programs. After a stint at the White House, Dr. Schaefer returned to school and received a PhD in atmospheric science in 2007. After a postdoc at NOAA, Dr. Schaefer started working at the National Snow and Ice Data Center in 2009.
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