The MANTRA campaigns - studying the stratosphere from balloons

The MANTRA (Middle Atmosphere Nitrogen Trend Assessment) series of high-altitude balloon flights is being undertaken to investigate changes in the concentrations of mid-latitude stratospheric ozone, and of nitrogen and chlorine compounds that play a role in ozone chemistry. Two balloons have been launched from Vanscoy, Saskatchewan, the first in August 1998 and the second in August 2000. Each carried a payload of instruments to measure vertical concentration profiles of stratospheric trace gases, and made observations from a float altitude of about 35 km for one day. Several of these instruments were flown 15-20 years ago and thus provide a link to historical data predating the onset of mid-latitude ozone loss. We are now preparing for two additional MANTRA flights, in 2002 and 2003. These new flights will extend the number of trace gases measured, and will include most of the previously flown instruments along with several new ones. This will enable a comparison of measurements of the same gases made by different instruments for the investigation of previously observed discrepancies and an assessment of the instruments' performance. The measurements will also be used to quantify changes in the chemical balance of the stratosphere, with a focus on changes in nitrogen oxides. In addition, the resulting data will be used for validation of several satellite instruments.