The ESA Medium Resolution Imaging Spectrometer MERIS - a review of the instrument and its mission

Following the successful operations of the ERS-1 and 2 satellites which are mainly dedicated to physical oceanography and ice observations from space, the European Space Agency (ESA) developed a multidisciplinary Earth observ ation instrument within its polar Earth Observation Programme with a focus on biological ocean observations. The Medium Resolution Imaging Spectromete r (MERIS) will be launched onboard Envisat-1 in the 1999-2000 time frame, p roviding a European remote sensing capability for observing for example oce anic biology and marine water quality through observations of water colour: MERIS will have a medium spectral and high radiometric resolution and a dua l spatial resolution, within a global mission, covering open ocean and coas tal zone waters, important aspects of the atmosphere, and large ecosystems over land. The global mission of MERIS will have a major contribution to sc ientific projects aimed at greater understanding of the role of oceans and ocean productivity in the climate system and our ability to forecast change through models. Secondary objectives of the MERIS mission will be directed to the measurement of atmospheric parameters associated with clouds, water vapour and aerosols in addition to land surface parameters, important in p articular for the understanding of vegetation processes. In advance of the launch of MERIS, algorithms are being developed for the i nterpretation of MERIS observations and dedicated studies are ongoing to es tablish the means of validating the data products. The aim of this paper is to provide a comprehensive overview of the MERIS c oncept, its mission and data products in context of the driving scientific requirements.