| Summary: | A field campaign for validation of the snow albedo product (SAL) of CM-SAF was arranged in Northern Finland in late April 2004. Both vertical and horizontal albedo profiling based on helicopter were carried out. In addition, ground based measurements of forested and open snow covered terrain were compared with the satellite based albedo values. The mean accuracy of the SAL product snow surface albedo was 3 % (absolute units) when compared to ground based measurements. Also the onset of the melting season was quite as evident in the satellite albedo data as in the ground measurements. The airborne data was used mainly for qualitative spatial variation analysis, because the vertical profiles showed clearly that the absolute value of the albedo varies with the flight altitude due to the variation of the land cover structure in the field of view. The spatial variation of the winter time surface albedo value is dominated by the variation of the land cover structure. In fact, there is a high correlation between the video image red intensity and surface albedo value and thus with the fraction of open terrain.
|
|---|