In the frame of the EUMETNET Programme of European Met Services, and in close co-operation with the Central Insitute for Meteorology and Geodynamics (Vienna), further development of the European operational weather radar network is carried out. This activity builds upon achievements from a previous similar undertaking, i.e. "CERAD" - Development and Implementation of the Central European Weather Radar . Key activities are the standardisation and operational implementaiton of radar data acquisition, coding, transmission and archiving, in the framework of relevant WMO rules and facilities (GTS network). K. Köck from the institute acts as the OPERA Programme Manager. The institute further contributes key elements in technical planning and project execution, based on long-term experience in dealing with precipitation measurement by radar (co-operation with Joanneum Research Graz in developing and operating/applying the multi-parameter C-band research weather radar Graz/Hilmwarte, development of radar network and terminal software for Austro Control) and on participation in relevant international projects (EU Research Actions COST- 72, -73 und -75, WMO Liaison Group on Operational European Weather Radar Networking - LGOEWRN). Development of the system concept for an international weather radar compositing system, presently involving 10 central European countries; implementation of communications and software tools, provision of call-in support