In addition to ground based measurements of nitric acid (HNO3), altitude profiles of nitric acid was conducted during the autumn, winter and spring using a series of balloon packs flown into the stratosphere. Each of the packages weighed approximately 60 kgs and consisted of instruments to measure nitric acid, the concentration of aersol particles of different sizes, temperature and ozone. Supporting flights were flown to measure water vapour and additional flights to monitor aerosol particle, ozone and condensation nuclei in the late winter and early spring period. The aim was to gain a detailed picture of the process of polar stratospheric cloud formation and the dehydration and denitrification that accompany it.
This was a cooperative program with the Universities of Denver and Wyoming. The climate monitoring group of NOAA in Boulder, Colorado(http://www.noaa.gov/) provided supporting flights and copies of the data may be retained from them if not from the principal investigator Stephen Wood.