Tropical cirrus clouds near cold point tropopause under ice supersaturated conditions observed by lidar and balloon‐borne cryogenic frost point hygrometer

Simultaneous vertical profiles of cirrus cloud backscattering and frost point temperature were obtained for the first time in the tropopause region over Bandung, Indonesia, (6.9°S, 107.6°E). These profiles were measured by ground‐based lidar and by balloon‐borne Cryogenic Frost point Hygrometer (CFH) sondes. Supersaturation up to several ten percent was observed by the CFH just below the cold point tropopause at the altitude where a cirrus cloud was observed by lidar. The water vapor mixing ratio decreased slightly at the altitude of the cirrus cloud, suggesting that this decrease was caused by uptake in the cirrus cloud and that the water vapor reduction corresponds to the lower limit of the cloud water content of the observed cirrus cloud. Theoretical calculations of the scattering parameters for the observed cirrus cloud particles and estimations of the time constants for sedimentation and for condensational growth indicate that particles size range is between 4 μm and 30 μm.