Phase: RAMI4PILPS
The Common Land model (CoLM) [Dai et al., 2003, 2004] features an improved two-stream approximation model of radiation transfer of the canopy, with attention to singularities in its solution and with separate integrations of radiation absorption by sunlit and shaded fractions of canopy.
To perform the various RAMI4PILPS experiments, the CoLM model solved the two-stream functions to get the reflected (Rveg) and transmitted (Τveg) fluxes in those areas covered by vegetation (assuming that the woody content was zero).
It then used the fractional vegetation cover (ƒveg) to obtain the total reflected flux, R = ƒveg · Rveg + (1 − ƒveg) α, and transmitted flux, Τ = ƒveg · Τveg + 1 − ƒveg, where α is the background albedo.
From these results the canopy absorption was then derived using the energy balance equation: A = 1 − R − (1-α)Τ.
The computer language of the CoLM implementation is Fortran 90.
It took less than 0.05 s to execute a single run on an ia64 machine with a SUSE Linux operating system and eight 1.4 GHz Intel Itanium processors having 8 Gb of RAM.
