The chlorophyll variability in meteosat derived NDVI in a context of drought monitoring

In this study we propose a validation method for the Meteosat SEVIRI derived NDVI values in regards to vegetation health from ground observations. The percentage of vegetation cover and the chlorophyll content are selected as vegetation health variables and their variability within and between SEVIRI pixels are assessed. No significant variability was found within pixels but between pixels for each of the variables. These variables are compared first separately with NDVI values, and later combined, with the NDVI values composited at different time steps. Results show that the combination of variables shows a similar trend than the mean NDVI or max NDVI calculated for the whole period of the study, as the presence of clouds influenced the daily NDVI values. We conclude that NDVI values can be used without compromising the variability of chlorophyll content and percentage of vegetation cover within those pixels. This funding can be used to understand the variation of NDVI which can be observed during a drought period.