Towards a Climatology of Australian Land Surface Albedo for use in Climate Models

IAN F. GRANT

CSIRO Atmospheric Research, Australia

Abstract: This paper describes the motivation and an approach for deriving a time series of albedo maps of Australia from historical Advanced Very High Resolution Radiometer (AVHRR) data. Polarization and Directionality of the Earth's Reflectances (POLDER) measurements will be used to test the angular correction algorithm. Some initial results from a survey of POLDER directional reflectance signatures of Australian land cover are presented. Those results show that, while there is much correspondence between the spatial patterns ofdirectional signatures and land cover types, there is a large spread of signatures within each land cover type. However, the similarity of two of the kernels of the bidirectional reflectance distribution function (BRDF) model used to parameterise the directional signatures can produce spurious variations in the model parameters. Finally, some field measurements ofgrassland albedo are 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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