6533b836fe1ef96bd12a1c50

RESEARCH PRODUCT

About the Problem of Scaling from Ground Measurements to Low Resolution Satellite Data

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Only satellite data can really produce "global" datasets, and the role of satellite data in the study of global processes is really essential, but ground measurements are also needed to calibrate satellite data and to validate models routinely working with satellite data inputs. The problem of comparing ground measurements with the measurements made by a satellite, particularly in the case of low resolution data (as NOAA AVHRR) imply the consideration of the problem of scaling, both in the case of particular measurements and in the case of mathematical models relating such measurements. Within the context of the EFEDA field experiment, the problem of scaling from ground measurements to low resolution satellite data has been addresed by using high resolution LANDSAT data in the transition from ground data to AVHRR data. The change with the spatial scale in the observation of the measured values of NDVI is analyzed by comparing TM and AVHRR data with ground measurements (simultaneously made at the time of the satellite overpass), for a geographical area with a spatial structure ideally appropriated to study the problem of the spatial average of the values. I. INTRODUCTION