The "Reflective Optics System Imaging Spectrometer" (ROSIS) is a compact, programmable imaging spectrometer based on a CCD matrix detector array. The optics of the system is made of reflective components only. The present horizontal resolution is 500 pixels across -track for a one -camera system with 32 selectable channels out of 85 within the spectral range 430 -850 nm. The spectral mode permits all 85channels to be read using every third across -track pixel. The instrument has been designed specifically for the monitoring of water colour and of natural chlorophyll fluorescence in order to derive concentrations of phytoplankton chlorophyll and other pigments, suspeded matter and yellow substance, and to map their horizontal distribution in the sea. However, its high spectral resolution (of 5 nm) and flexibility also permits new applications in the remote sensing of atmospheric parameters such as cloud -top height and vegetation monitoring. An airborne prototype of ROSIS is being jointly developed at present by MBB, GKSS and DFVLR. ABSTRACTThe "Reflective Optics System Imaging Spectrometer" (ROSIS) is a compact, programmable imaging spectrometer based on a CCD matrix detector array. The optics of the system is made of reflective components only. The present horizontal resolution is 500 pixels across-track for a one-camera system with 32 selectable channels out of 85 within the spectral range 430 -850 nm. The spectral mode permits all 85 channels to be read using every third across-track pixel. The instrument has been designed specifically for the monitoring of water colour and of natural chlorophyll fluorescence in order to derive concentrations of phytoplankton chlorophyll and other pigments, suspeded matter and yellow substance, and to map their horizontal distribution in the sea. However, its high spectral resolution (of <5 nm) and flexibility also permits new applications in the remote sensing of atmospheric parameters such as cloud-top height and vegetation monitoring. An airborne prototype of ROSIS is being jointly developed at present by MBB, GKSS and DFVLR.