An experimental study of the tree canopy-urban surface system optical and thermal signatures

Remote sensing for vegetation monitoring can involve mixed pixels with contributions from vegetation and background surfaces, causing biases in signals and their interpretations. This is especially so in cases when remote sensing applications are deployed in conditions with sparse vegetation, such as trees in urban areas, where multiple components within a pixel need to be considered; in such cases, the contained spectral information can be difficult to interpret.

A ground-based experimental layout consisting of a spectrometer and a thermal camera mounted on a portable crane for assessing the optical and thermal signatures of the tree canopy - underlying surface system, was deployed in a controlled field experiment. Two groups of five identically arranged containerised Acer platanoides 'Columnare' were placed into two adjacent built and non-built local microenvironments. Using the obtained thermal signatures, the relative contribution of the underlying surface and tree canopy to the overall spectral reflectance variation was examined.

A moderate correlation between the canopy-background temperature difference and the spectral reflectance for the built local microenvironment indicates that the synergy between thermal and spectral measurements in the fine scale is a promising method for disentangling the combined signal components. Further results will be presented in the conference.