HR: 09:15h
AN: C31A-06    [PDF]
TI: ICESat Observations of Forest Canopy Height
AU: * Harding, D J
EM: david.j.harding@nasa.gov
AF: NASA's Goddard Space Flight Center, Mail Code 921, Greenbelt, MD 20771 United States
AU: Carabajal, C C
EM: claudia@stokes.gsfc.nasa.gov
AF: NVI @ NASA's Goddard Space Flight Center, Mail Code 926, Greenbelt, MD 20771 United States
AB: The Ice, Cloud and Land Elevation Satellite (ICESat), a component of the NASA Earth Observing System, was launched into orbit on January 12th, 2003. The ICESat mission acquires globally distributed profiles with the Gesoscience Laser Altimeter System (GLAS), providing observations of ice sheet elevation, cloud and aerosol heights, land topography and vegetation characteristics. Vegetation height is a key indicator of the amount of above-ground carbon stored in forests, which is an essential component in the cycling of carbon dioxide between the Earth's atmosphere and land surface. Vegetation height is also a useful indicator of forest age and habitat quality. Traditional orbital remote sensing methods are not well suited to measure vegetation height. The laser altimeter waveforms recorded by the GLAS instrument provide a global means to sample the height of vegetation along the ICESat profiles. In forested areas where the ground is flat or gently sloping, we observe that the waveforms record the laser pulse reflected from vegetation and, slightly later in time, the reflection from the ground. The time difference between these two echoes yields a direct measurement of maximum canopy height. As anticipated, in areas of steep terrain, the vegetation and ground returns become mixed together in the waveforms, making the analysis more difficult and requiring independent information on ground slope at the laser footprint location. We illustrate waveform retrieval of canopy height for low slope settings for several forest ecosystems, and validate the GLAS height retrievals for Pacific Northwest forest stands using a technique that matches observed and simulated waveforms where extensive high-resolution airborne laser mapping of ground topography and vegetation height is available.
DE: 0400 Biogeosciences
DE: 1294 Instruments and techniques
DE: 1640 Remote sensing
SC: Cryosphere [C]
MN: 2003 Fall Meeting