Compatibility and integration of NDVI data obtained from AVHRR/NOAA and SEVIRI/MSG sensors.

A statistical analysis on the compatibility of NDVI indices is presented, which is obtained with data collected by AVHRR and SEVIRI (METEOSAT Second Generation – MSG) sensors, directly received at the Satellite Receiving Station of Department of Electronics and Telecommunication (DET) - University of Florence, located in Prato (Italy). The goal of this analysis is evaluation of the level of compatibility between the NDVI indices from AVHRR and SEVIRI, so as to extract indications for possibly integrating data from those sensors, exploiting their characteristics (high temporal frequency of available images – an image every 15 minutes – and the geometric invariance of the Earth-Satellite view for SEVIRI; AVHRR’s finest spatial resolution). SEVIRI’s and AVHRR’s NDVI to be compared were obtained with the same procedure, from data continuously received from January to December 2008 addressing the Tuscany Region, Italy. The processing was carried out using the classical formula (difference and sum ratio of near infrared and red reflectance) and a monthly-based maximum value composite (MVC) technique, so as to limit atmospheric effects. The monthly composite images were then geolocated and registered on Mercator maps with a nearest neighbour interpolation method. Statistical comparison between SEVIRI and AVHRR monthly maps was performed through histograms and scatter plots analysis and through the evaluation of medium values, variances and correlation coefficient. For the considered geographic area and the time period of interest, results show a good concordance between SEVIRI’s and AVHRR’s NDVI, encouraging the possibility of a combined used of the two sensors.