HR: 1340h
AN: B33A-1023    [Abstracts]
TI: Pan-Arctic Freeze/Thaw Algorithm Development Using AMSR-E Data and Satellite Remote Sensing Technique
AU: * Nirala, M L
EM: mohan@ntsg.umt.edu
AF: Numerical Terradynamic Simulation Group, NTSG, University of Montana, Missoula, MT 59812 United States
AU: Kimball, J
EM: johnk@ntsg.umt.edu
AF: Numerical Terradynamic Simulation Group, NTSG, University of Montana, Missoula, MT 59812 United States
AU: Kimball, J
EM: johnk@ntsg.umt.edu
AF: Flathead Lake Biological Station, Division of Biological Sciences, 311 Biostation Lane, Polson, MT 59860 United States
AU: Running, S
EM: swr@ntsg.umt.edu
AF: Numerical Terradynamic Simulation Group, NTSG, University of Montana, Missoula, MT 59812 United States
AU: McDonald, K
EM: kyle.mcdonald@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 United States
AU: Oechel, W
EM: oechel@sunstroke.sdsu.edu
AF: Global Change Research Group, Department of Biology San Diego State University , San Diego, CA 92182 United States
AU: Njoku, E
EM: eni.g.njoku@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 United States
AB: We have developed an algorithm to determine freeze/thaw state in the pan-Arctic region using microwave brightness temperature and surface air temperature. We estimated emissivity using AMSR-E brightness temperature and ground air temperature. We found a strong linear relationship between AMSR-E surface emissivities and surface temperature at 6.9 and 36.5 GHz horizontal and vertical polarizations over arctic land surfaces. The results show that the 37 GHz channel demonstrates better surface temperature, while 6.9 indicates some unambiguous identification of RFI. Microwave- derived surface temperatures are compared with ground-based data over boreal-arctic flux tower sites. Analysis of the land surface temperature reveals that variation in short term (a few days) brightness temperature at 37 GHz is sensitive to air temperature changes. The amplitude of fluctuation in freeze/thaw is sufficiently large to be detected. Using this approach, we generated annual trends of emissivities which are used to evaluate freeze/thaw algorithm for arctic land covers. The microwave-derived surface temperature and soil moisture are used to estimate NEE at the boreal-arctic region and validated using flux tower sites data. Our results also indicate that carbon cycle response to climate change is nonlinear and strongly coupled to arctic surface hydrology. Calibration and validation activities involve comparisons between satellite remote sensing and tundra CO2 eddy flux tower and biophysical measurement networks and hydroecological process model simulations. We analyze spatial and temporal anomalies and environmental drivers of land-atmosphere net CO2 exchange at weekly and annual time steps. This work was performed at The University of Montana and Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
DE: 0480 Remote sensing
SC: Biogeosciences [B]
MN: Fall Meeting 2005