The variability of satellite derived surface BRDF shape over Australia from 2001 to 2011

The intra- and inter-annual variability of surface bidirectional reflectance distribution function (BRDF) in Australia has been analyzed using 11 years (2001-2011) of MODIS BRDF data. A statistic called here Root Mean Square (RMS) was used as a BRDF shape indicator to represent the overall BRDF shape and an Australian vegetation structure map was used to separate the different BRDF shape patterns by structure. The results show that the intra-annual variation of BRDF shape is stronger than the inter-annual variation although it is not clear yet whether the variation is related more to climate patterns or to vegetation structure (height and cover) or landcover class. However, BRDF shape patterns have strong similarity with vegetation structure classes. There is strong correlation between RMS and the Normalized Difference Vegetation Index (NDVI) at annual scale within structural classes indicating good relationship between BRDF and annual changes in cover within the classes.