Introduction to the EUCREX-94 mission 206

Part of the EUCREX-94 experiment was devoted to the study of the radiative properties of boundary layer clouds in relation with their microphysical and structural properties. Mission 206, on April 18, is particularly attractive because of a general trend in cloud geometrical thickness within the sampled region, with corresponding values of optical thickness between 4 and 70. The cloud system has been extensively documented in situ with an instrumented aircraft, while two other aircraft were measuring its radiative properties with radiometers and a lidar. This paper introduces the scientific objectives of the experiment and describes the instrumental setup. After a presentation of the meteorological situation, the various papers of this series are briefly introduced.