Ground-based Raman-lidar for day and night measurements of water vapor in the boundary layer

The solar-blind Raman-lidar based on a KrF laser (248 nm) developed at Lecc e's University (40 degrees 20' N, 18 degrees 6' E) is described. The lidar is currently used for day and night measurements of water vapor. The depend ence of the measurement range of the lidar on the laser beam divergence is investigated and it is shown that the KrF laser beam divergence can be redu ced by a factor similar to 10 by using a quite simple unstable cavity confi guration. The maximum range which was limited to approximately 500 m for a similar to 3 mrad divergence laser beam has increased up to 1200 m with a s imilar to 0.3 mrad divergence laser beam since the field of view of the tel escope was of 1 mrad. Water vapor profiles retrieved from lidar measurement s under different operating conditions are presented. The effect of boundar y-layer ozone absorption has also been investigated.