Results from the VISA project

The small lidar system has been used to measure the vertical structure of the atmospheric extinction in a dune area bordering The Hague (The Netherlands), at about 2.6 km from the North Sea. The atmospheric optical properties at this location are determined by a mixture of industrial, urban, rural and marine aerosols, which composition depends on the air mass history. The measurements were made unattended, around the clock, five days a week. About 250 extinction profiles were recorded every day. This report reviews the data base obtained and presents some selected results. The lidar system is described briefly. Factors influencing the accuracy of the inversion of lidar signals are discussed.