Cirrus climatological results front lidar measurements at OHP (44 degrees N, 6 degrees E)

A climatology of cirrus clouds over the Observatoire de Haute Provence in F rance has been constructed from the analysis of ground-based lidar measurem ents taken from 1997 to 1999. During this period the high-resolution Raylei gh/Mie lidar collected 384 nights of measurements and cirrus profiles are o bserved in about half of these cases. We find subvisible cirrus (tau < 0.83 ) constitute <similar to> 20 % of cirrus cloud occurrences and that the mea n thickness of a subvisible cirrus cloud layer is less than 1 km. A discuss ion of the error associated with these determinations is also presented.