Comparison of energy fluxes calculated with the Penman-Monteith equation and the vegetation models SiB and Cupid

Abstract

This study compares measured and modelled energy fluxes and surface temperatures calculated with three land-surface parametrization schemes of varying complexity. The Penman-Monteith equation, the big-leaf model SiB and the multilayer model Cupid have been tested with data from the LOTREX 10E/HIBE89 experiment. Two days with almost clear sky, 5 and 6 July 1989, were chosen for the present tests. Soil and vegetation input parameters were taken from the literature and from field observations. All three models capture the magnitude and behaviour of the energy balance terms. Cupid, which is the most complex of the three models, shows the best agreement between measurements and simulations, with the advantage that the intercomparison of vertical profiles of temperature, humidity and wind within and above the vegetation is possible. The partitioning between sensible and latent heat fluxes predicted with the Penman-Monteith equation is also in good agreement with the measurements, taking into account the simplicity of this method. Discrepancies are observed in the relative contributions of the canopy transpiration and surface evaporation to the total latent heat flux calculated with SiB and Cupid.