Scaling to the MERIS resolution: Mapping accuracy and spatial variability

Within the framework of ESA's Earth Observation Programme, the Medium Resolution Imaging Spectrometer (MERIS) is developed as one of the payload components of the ENVISAT-1, expected to be operational in 1999. MERIS is a fully programmable imaging spectrometer, however a standard 15 channel band set will be transmitted for each 300 m. pixel lover land) covering the visible and near-infrared wavelength range. In preparation of MERIS, studies on simulated data are being conducted to explore the potential of the instrument for land applications. Algorithms to spectrally and spatially degrade airborne imaging spectrometer data sets to match the MERIS resolution are presented including a data set derived from GERIS 63 channel data over a agricultural site in central Spain (the Almaden test site. MERIS data at spatial resolutions varying from 12 meter up to 300 meter are spatially analyzed using variogram surfaces. These allow to gain insight into the nature of the data and its spatial dependency showing however little noticeable changes even at a sub-pixel level. However when evaluating mapping accuracy clearly different optimal sampling sizes are found for the different end members. For the "soil" endmember the smallest resolution is optimal however for "vegetation" endmember a resolution around 100 m. optimizes the estimation of local variance.