Contributions of multi-view angle remote sensing to land-surface and biogeochemical research

Land-surface and biogeochemical research is growing in its dependence upon quantitative vegetation structural and functional information from remote sensing. Multiple view angle (MVA) remote sensing has rapidly evolved from a few modeling and measurement efforts to operational algorithms and spaceborne instruments capable of analyzing the information contained in the angular reflectance signature of the Earth's surface and atmosphere. The shape of the bidirectional reflectance distribution function (BRDF) of vegetation and atmospheric constituents is most sensitive to the orientation and location of the photon scatterers in 3-dimensional space (e.g., foliage at canopy and landscape scales). Early evidence indicates that MVA measurements will contribute the most to land-surface and biogeochemical research efforts: (1) by providing unique information on changes in the spatial distribution of the scatterers (e.g., foliage) associated with vegetation structural changes that result from disturbance such as land-use, wildfire, and wind, and (2) by accounting of artifacts inherent to single-angle optical remote sensing time series data resulting from solar and view geometry changes and atmospheric perturbations (e.g., aerosols). Examples of each are developed and presented as a means to highlight some issues for land-surface and biogeochemical research and the ways in which MVA measurements can make a contribution.