Conclusions

This paper has outlined an approach to developing a robust algorithm to derive albedo and time series of reflectances that are corrected for view direction effects from AVHRR time series. POLDER top-of-the-atmosphere radiance measurements will be used to test the algorithm. Some initial results from a survey of POLDER directional reflectance signatures of Australian land cover were presented, which showed that while there was much correspondence between the spatial patterns of directional signatures and land cover types, there was a large spread of signatures within each land cover type. However, the similarity of two of the kernels of the BRDF model used to parameterise the directional signatures can produce spurious variations in the model parameters. Finally, some field measurements of grassland albedo were used to make the point that for the greatest accuracy in the estimation of land surface albedo from satellites, it is necessary to account for the detailed shape of the diurnal variation and the effect of the cloudiness on albedo.

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