A two-source energy balance approach using directional radiometric temperature observations for sparse canopy covered surfaces

A two-source energy balance model developed to use directional radiometric surface temperature for estimating component heat fluxes from soil and vegetation has had several recent modifications to account for some of the unique properties associated with sparse canopies. Two of these changes involve the algorithms predicting the divergence of net radiation inside the canopy and how to account for clumped vegetation, which affects both the wind and radiation penetration inside the canopy and radiative temperature partitioning between soil and vegetation components. Model results with and without these modifications are compared using data collected from a sparsely vegetated row crop of cotton (Gossypium hirsutum L, cv. Delta Pine 77), it is suggested that these two new algorithms be incorporated in any two-source model applied to sparse canopies.