Reflectance spectroradiometer measurement system in 30 meter mast for validating satellite images

Reflectance spectroscopy is a well established field of research, evolved from simple laboratory instruments into a satellite-oriented global environment research tool. However, due to the effect of the atmosphere and the large area coverage of satellite images, reflectances extracted from satellite data or ground based spectra are not correlating properly. In order to improve the comparability of satellite-borne and ground-based reflectance observations, we have constructed a reflectance spectrometer measurement assembled to a 30 meter mast. With this construction we are able to average reflectance spectra from up to 400 m² area in the ground and up to 180 m² area in the level of tree tops, respectively. A primary function of our measurement system is the correction of satellite images from atmospheric effects. This paper presents the measurement system for validating satellite images, constructed to Arctic Research Centre in Sodankylauml. The operative measurements in the system started at the summer of 2006.