Środowiskowe Seminarium Fizyki Atmosfery

Cloud properties are of crucial importance for climate change studies. It is essential that global observation systems placed on satellit platforms are used for their observation. Only such an approach makes it possible to determine global cloud properties and corresponding changes on global and regional scales. Such trends have already been reported for cloudiness over Europe effected by the collapse of Soviet Union and change of economies in countries of Eastern Europe.In this presentation a survey of modern passive techniques to retrieve cloud properties from satellite observations in the optical spectral range (visible-near IR) is given. The techniques to determine the cloud top height (and bottom) positions, the effective radius of droplets and cloud liquid water path are described in detail. The main emphasis is given to retrievals performed with the use of SCIAMACHY instrument onboard ENVISAT (launched on March 1, 2002). The SCIAMACHY measures the top-of-atmosphere reflectance in the spectral range 0.24-2.4 micrometers with high spectral resolution (usually 0.2nm). The high spectral resolution is essential for the determination cloud altitudes and also for the determination of abundances of trace gases such as O3, NO2, CO, CO2 and CH4.