Calibration adjustment of the NOAA AVHRR Normalized Difference Vegetation Index without recourse to component channel 1 and 2 data

The effect of sensor degradation in the Advanced Very High Resolution Radiometer (AVHRR) channels 1 and 2 on the Normalized Difference Vegetation Index (NDVI) has been established. Three models have been developed that adjust NDVI for sensor degradation without recourse to component channel 1 and 2 data. The models have been verified with data obtained by the AVHRR on board of NOAA-7, -9 and -11. Two models provide accurate results in some cases, but perform less well in others. A third model is applicable to all cases investigated, and estimates the effect of sensor degradation with a maximum RMS error of 0·002NDVI. The remaining error depends on surface characteristics and the magnitude of sensor degradation, and cannot be accounted for without the component channel 1 and 2 data.