HR: 1340h
AN: B43C-1460    [Abstracts]
TI: Modeling the Impact of Vegetation Structure on Canopy Radiative Transfer for a Global Vegetation Dynamic Model
AU: * Ni-Meister, W
EM: wenge.ni-meister@hunter.cuny.edu
AF: department of Geography Hunter College of The City University of New York, 695 Park Ave, New York, NY 100065, United States
AU: Kiang, N
EM: nkiang@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, United States
AU: Yang, W
EM: wyang@hunter.cuny.edu
AF: department of Geography Hunter College of The City University of New York, 695 Park Ave, New York, NY 100065, United States
AB: The transmission of light through plant canopies results in vertical profiles of light intensity that affect the photosynthetic activity and gas exchange of plants, their competition for light, and the canopy energy balance. The accurate representation of the canopy light profile is then important for predicting ecological dynamics. The study presents a simple canopy radiative transfer scheme to characterize the impact of the horizontal and vertical vegetation structure heterogeneity on light profiles. Actual vertical foliage profile and a clumping factor which are functions of tree geometry, size and density and foliage density are used to characterize the vertical and horizontal vegetation structure heterogeneity. The simple scheme is evaluated using the ground and airborne lidar data collected in deciduous and coniferous forests and was also compared with the more complex Geometric Optical and Radiative Transfer (GORT) model and the two-stream scheme currently being used to describe light interactions with vegetation canopy in most GCMs. The simple modeled PAR profiles match well with the ground data, lidar and full GORT model prediction, it performs much better than the simple Beer's&plaw used in two stream scheme. This scheme will have the same computation cost as the current scheme being used in GCMs, but provides better photosynthesis, radiative fluxes and surface albedo estimates, thus is suitable for a global vegetation dynamic model embedded in GCMs.
DE: 0360 Radiation: transmission and scattering
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0466 Modeling
DE: 0480 Remote sensing
SC: Biogeosciences [B]
MN: 2007 Fall Meeting