Adaptation and validation of a voxel based energy transport model for conifer species

Abstract

A spatially explicit energy balance model previously developed for deciduous trees was extended to account for physical differences in conifer species. These differences include the emission and scattering of radiation in needles compared to leaves as well as the boundary-layer conductance for needles. To validate the model, an array of sensors was placed in and around two separate isolated Picea pungens trees in a heterogeneous urban environment. Model validation examined components of the local-volume averaged needle energy budget utilizing radiative and turbulent fluxes as the forcing inputs. Analysis focused on the model's ability to reproduce integrated upward shortwave and longwave radiation, local radiation attenuation through the tree crown, and local needle surface temperature. The model performed quite well with R2 values above 0.9 for calculated versus measured integrated upward longwave and shortwave radiation and above 0.87 for needle surface temperature. The high level of agreement with experimental measurements was only possible with the modifications made to the boundary layer conductance for needles.