Approach and validation on land surface albedo retrieval using multiangular remote sensing observations

The main problem in the validation is that the field-measured albedo is different in scale from the albedo estimated using remote sensing data. The albedo-meter based field measurement is over a small area. On the contrary, the spatial resolution of the MODIS albedo production is about 1 km. Another problem is the different wavebands or albedo-meter and MODIS sensor. As a solution, we suggest to use the field multiangular measurements data that is captured in a small field of view (FOV) to retrieve the albedo by Ambrals model inversion. As a result, the retrieved albedo is comparable with that measured by albedo-meter since they have the same scale. At the same time, the effect of wavebands difference is also corrected. In the second step, we extend this method to the airborne MARS observations of the same target. Scaling-up can be considered based on the two inverted albedos. The retrieved albedo from airborne data can be validated using field measurement too. Finally, the airborne retrieved albedo can be used to validate the MODIS albedo production. In this framework, the field measured data sets come from a large satellite-airborne-ground synchronous experiment that was taken in Shunyi, which is in the north of Beijing, in April of 2001.