New Version of Balloon Hygrometer for in Situ Water Vapour Measurements in the Upper Troposphere and Lower Stratopshere (flash-bm)

The fluorescent technique is well recommended for in situ water vapor measurements in the upper troposphere, stratosphere and mesosphere on board balloons, highaltitude aircrafts and rockets. New version of the balloon optical fluorescent hygrometer (FLASH-BM) is presented. Special attention is devoted to the calibration procedures, stability, accuracy and precision of the flight instrument. New version of the vacuum ultraviolet hydrogen lamp is used for dissociation of the water vapour molecules. Technical specifications of this lamp as well as the procedure of the absolute calibration of its intensity are described. Some results of FLASH-BM test flight are presented and discussed.