MISR abstract

Widlowski, J., Pinty, B., Gobron, N., Verstraete, M., Diner, D.J., Davis, A.B.,. (2002). Detection of Surface Structure and Heterogeneity using MISR/Terra observations. Eos Trans. AGU, 83(47), Fall Meet. Suppl. 2002, Abstract # B21A-0713

The recent availability of quasi-simultaneous multispectral and multidirectional measurements from space, as provided by the Multiangle Imaging Spectro-Radiometer (MISR) on board the Terra platform, offers new and unique opportunities to document the anisotropy of land surfaces at critical solar wavelengths. This contribution outlines simple physical principles supporting the interpretation of the anisotropy of spectral radiances exiting terrestrial surfaces in terms of a signature of surface heterogeneity. The shape of the anisotropy function is represented with two model parameter values which may be mapped and interpreted in their own right. Beyond the information about the heterogeneity of the surface, the value of one of these parameters also permits identifying geophysical conditions where the surface heterogeneity becomes significant. Structure functions and singularity measures can be employed to describe the non-stationary and intermittent behaviour of geophysical fields. This approach is applied on synthetic height field measurements of a large variety of vegetation canopies. The joint analysis of the shape of the anisotropy function together with the height fields yields remarkable patterns of organization: It is possible for multiangular instruments, like MISR, to deliver information about the type of surface heterogeneity at the subpixel scale, that is in agreement with canopy structure characterizations obtained by other means.

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