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

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