Quality assurance in the FMI Doppler Weather Radar Network

The Finnish Meteorological Institute designed, acquired and installed a network of 8 C-band Doppler radars during the years 1993-2005.We describe the principles used in the network design, the basic infrastructure of the network, as well as the technical properties of the radars.Data quality is improved by filtering of unwanted echoes and thresholding, and the electrical calibration of power and the antenna pointing is controlled by pairedradar analysis and solar observations.The radar data are used to serve society in a wide range of applications from aviation weather service to flood protection.High quality of end-user products is achieved by maintaining optimal measurements of individual radars, homogeneity of the entire radar network, and careful processing of the data.Volume scans consisting of 11 elevation angles have been designed to give simultaneously good quality precipitation data near the surface, secondly, good quality wind profiles based on the Doppler data, and thirdly, three-dimensional data (cloud tops and cross sections) for the requirements of aviation.Doppler-filtering, image processing and adjustment for vertical profile of reflectivity are applied to improve the data quality.