Comparison of water vapour soundings in the upper troposphere
Abstract
We report on a study to compare upper tropospheric humidity measurements by three devices: Vaisala RS80 radiosondes, Meteolabor Snow White frost-point hygrometers and surface acoustic wave (SAW) hygrometers from the University of Cambridge, UK. The SAW hygrometer is a new frost-point instrument in which a SAW device replaces the chilled mirror of a conventional frost-point hygrometer. The SAW device responds to much smaller amounts of condensate, thereby increasing sensitivity and reducing response time. This hygrometer is the only one of the three designed to be capable of measurement of the low ppmv-levels of stratospheric water vapour. The three devices were flown as an integrated package, together with an ozonesonde, on a series of 30 flights from Aberystwyth, UK. Evaluation of the Snow White sonde led to a modification to monitor the phototransistor output during flight. We report on the relative performance of the three sensors and conclude that the standard radiosonde measurements are accurate in the upper troposphere, provided certain corrections are made.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....11432V