HR: 0800h
AN: C31A-1111    [Abstracts]
TI: The Annual Freeze-/Thaw Cycle in the Caribou Poker Creek Research Watershed, Alaska: Combining RADAR With Model Results
AU: * Schroeder, R
EM: ronny.schroeder@bgc-jena.mpg.de
AF: Max Planck Institute for Biogeochemistry Jena, Hans-Knoell-Strasse 10, Jena, 07745 Germany
AU: McDonald, K
EM: kyle.mcdonald@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 United States
AU: Kimball, J
EM: johnk@ntsg.umt.edu
AF: University of Montana, 311 BioStation Lane, Polson, MT 59860-9659 United States
AU: Podest, E
EM: erika.podest@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 United States
AU: Zimmermann, R
EM: rzimmer@uni-bonn.de
AF: University of Bonn, Walter-Flex-Strasse 3, Bonn, 53113 Germany
AB: A globally applicable method that uses RADAR remote sensing to detect the Freeze-/Thaw Cycle (FTC) on earth, e.g. in the boreal zone of North America or Eurasia, is shown. The focus of this work was the Caribou Poker Creek Research Watershed (CPCRW), which is a small area of relatively complex terrain in the interior of Alaska. We will demonstrate the potential of our FTC method, when combining the annual remotely sensed FTC map with modeled direct solar radiation load at the surface, which uses for the latter a Digital Elevation Model (DEM) as input. The result of our work confirms that the timing of thaw in spring is clearly a function of the solar intensity, which is driven mainly by topographic effects, in particular by the values of aspect and slope across CPCRW. For the freeze-up in autumn however it is speculated that the spatial distribution of water in the soil marks the end of the non-frozen period. In our study, this has caused the north facing slope freezing-up later than the drier south oriented slope, though the observed permafrost distribution in the area as well as our estimates of modeled clear-sky-radiation do not match with this result.
DE: 0704 Seasonally frozen ground
SC: Cryosphere [C]
MN: Fall Meeting 2005