Canopy Radiative Transfer for Global Vegetation Dynamic Models: Characterization of Foliage Clumping
Wenge
Ni-Meister, Hunter College of City University of New York, wenge.ni-meister@hunter.cuny.edu
(Presenting)
Nancy
Kiang, NASA Goddard Institute for Space Studies, nkiang@giss.nasa.gov
Paul
Moorcroft, Havard University, moorcrof@fas.harvard.edu
Calculation of canopy radiative transfer for simulation modeling of coupled biosphere-atmosphere interactions, such as in dynamic global vegetation models (DGVMs) coupled to atmospheric general circulation models (AGCMs), must be able to provide:
albedo of the vegetated land surface for the atmospheric model’s energy balance;2) incident radiation on foliage through the vegetation canopy for photosynthesis and stomatal conductance as controllers of land surface fluxes, and as determinant of vertical light competition amongplants;3) transmittance of radiation to the ground to predict soil temperature and snowmelt.
Clumping of foliage within plant canopies strongly influences the above three features, particularly as it affects the vertical profile of light in the canopy, which then strongly influences light competition within plant communities. For DGVMs, the level of clumping will change as vegetation structure changes due togrowth, senescence, and community dynamics. Acanopy radiative transfer algorithm for DGVMs mustbe able to quantify these structural changes andtranslate them to a measure of foliage clumping. Atthe same time, the algorithm must be computationally fast so as to be useful within a GCM.
We present new algorithms for quantifying foliage clumping and calculating canopy radiative transfer, developed for the Ent model, a new DGVM underdevelopment at NASA-GISS.