International audienceRaman water vapor Lidar start to investigated 20 years ago on existing lidars in the frame of the NDACC network located in South of France (44°N, 6°E) and in Reunion Island (21°S, 55°E) with elasting scatter to register simultaneously cristal particules. From this experiment, a nex system have been designed to monitor the water vapor in the whole troposphere up to the lower stratosphere. Measurements have been validated with CFH and Vaisala radiosondes. Measuring quantities of a few ppmv in the lower stratosphere is achiveded. Calibration methodology have been developped and tested during the campaign MALICCA (MAïdo LIdar Calibration CAmpaign). The lidar water vapor profiles are calibrated with water vapor columns obtained from a collocated GNSS receiver. New methodologies of data averaging have been developped, for a long-term monitoring and studies of water transport around the tropopause. Few cases studies are presented to illustrated lidar capabilities