Combined modelling of shortwave and thermal radiation for one-dimensional SVATs

Expressions for the upwelling and downwelling fluxes of optical and thermal radiation between soil, vegetation and the sky are derived, under certain simple assumptions. These are that interception of radiation by the vegetat ion is a purely geometric effect, while scattering is isotropic, with a str ength given by a single-scattering albedo in the optical part of the spectr um, and by Kirchoff's Law in the thermal. The soil is assumed to be a lambe rtian reflector, also scattering according to an albedo and Kirchoff's Law. The model, called RM, conserves energy exactly. As part of a SVAT, it is d riven by measured insolation instead of net radiation, with little increase in computational cost and number of parameters.