Das Projekt "European polar stratospheric cloud and lee wave experiment" wird vom Umweltbundesamt gefördert und von Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre ICG-1: Stratospäere durchgeführt. EUPLEX will critically test current hypotheses for the three key processes of arctic stratospheric ozone depletion chemistry: 1. PSC formation and properties in Lee-wave and synoptic scale PSC; 2. Halogen activation on PSC, and; 3. Chemical ozone loss. Optimum chemica1 and microphysical information will be measured on dedicated flights of a suitably instrumented high-altitude research aircraft employing two new flight strategies: 1. Quasi-Lagrangian flights through Lee-wave PSC; 2. Multiple flights probing the same air masses twice within time periods of several days. Comparison of these first-time observations and state of the art microphysical and chemical models will yield improved or new parameterisations or corroborate established concepts that are a prerequisite for numerical simulations to predict the future state of the azone layer.