HYGROSONDE - A DIRECT MEASUREMENT OF WATER-VAPOR IN THE STRATOSPHERE AND MESOSPHERE

A rocket-borne optical hygrometer for night time in situ measurements of the middle atmospheric water content was successfully launched from Esrange, Sweden, in December 1994. Utilizing the OH photofragment flu orescence technique, the instrument takes measurements in an undisturb ed volume outside the rocket shock front. A profile of water vapor was obtained between 17 and 70 km. The stratospheric mixing ratio increas es from 3.5 ppmv near 20 km to around 6 ppmv above 45 km, while the me sospheric profile shows a strongly stratified structure; The results a re discussed in terms of horizontal transport and compared to recently published model results on the redistribution of water vapor in the w inter polar mesosphere.