The relative merit of cloud/clear identification in the NOAA/NASA Pathfinder AVHRR Land 10-day composites

Abstract

Abstract The Pathfinder Advanced Very High Resolution Radiometer (AVHRR) Land (PAL) dataset is a new generation of globally mapped long-term datasets produced from AVHRR onboard NOAA satellites. The PAL data, particularly their compressed version—the 10-day composites, are expected to be used quantitatively in climate applications/modelling and land cover/land cover change studies. There are, however, geographic areas that are not limited to tropics, where the 10-day composites are not cloud free. As a result, significant errors in the Normalized Difference Vegetation Index (NDVI), reflectances and brightness temperatures may occur. The PAL daily data processing included cloud/clear identification using the Clouds from AVHRR (CLAVR) procedure. The CLAVR flags were appended to each pixel but were not used for generating PAL 10-day data products. In this Letter, we use global PAL data for July 1988 to estimate quantitatively the effect of residual cloud contamination on PAL composite NDVI, reflectance, and ...