HR: 0830h
AN: B31C-0319    [PDF]
TI: Detecting and Analyzing Trends in Freeze Thaw Cycles of High Northern Latitude Soils Using Passive Microwave Satellites Since 1988
AU: * Smith, N V
EM: nicolev@gps.caltech.edu
AF: California Institute of Technology Environmental Science and Engineering Division of Geological and Planetary Sciences, 1200 E. California Blvd. MS 100-23, Pasadena, CA 91125 United States
AU: Saatchi, S S
EM: saatchi@congo.jpl.nasa.gov
AF: Jet Propulsion Laboratory California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AU: Randerson, J T
EM: jranders@uci.edu
AF: California Institute of Technology Environmental Science and Engineering Division of Geological and Planetary Sciences, 1200 E. California Blvd. MS 100-23, Pasadena, CA 91125 United States
AU: Randerson, J T
EM: jranders@uci.edu
AF: University of California, Irvine Earth System Science Department, 3212 Croul Hall, Irvine, CA 92697 United States
AB: In the far north, soil respiration rates are controlled by a complex interaction of soil freeze state, active layer depth, soil moisture and substrate form and availability. The freeze thaw boundary represents a significant first order constraint on soil respiration and is detectable using satellite imagery. Using satellite data from the Special Sensor Microwave/Imager (SSM/I) spanning the period 1988-2002, we developed a technique to detect the timing of freeze and thaw of soils north of 45 degrees N. We analyzed both biome and site level trends in the onset of freeze and thaw since 1988. Our results indicate that the spring thaw advanced in both tundra and boreal forests of North America, and in tundra and larch forests in Eurasia. Fall freeze was delayed in both boreal and tundra North America, but advanced in both tundra and larch forests in Eurasia. Boreal Eurasia maintained nearly constant freeze and thaw timing since 1988. The growing season length increased in North America, but remained nearly constant in Eurasia due to both an earlier thaw and freeze in tundra and larch ecosystems.
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
DE: 1640 Remote sensing
DE: 1823 Frozen ground
SC: Biogeosciences [B]
MN: 2003 Fall Meeting