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Trace gases
Trace gases in the stratosphere
Trace gases in the stratosphere - destruction of stratospheric ozone by halogenated
hydrocarbons (CFC, HCFC etc.) - their vertical distribution measured using cryogenic
sampling (balloon borne "cryosampler") and subsequent gaschromatographic analysis
Science objectives
In 1974 Molina and Rowland alarmed the world with their hypothesis,
continuous emissions of halogenated hydrocarbons to be responsible for
a reduction of stratospheric ozone. This hypothesis and a tremendous
need for experimental data initialised this project in 1976. The main
task was the measurement of vertical distributions of all relevant
trace gases, achieved by using cryogenic sampling ("cryosampler")
with subsequent gaschromaotographic analyses.
Since then 25 balloon flights have been carried out at midlatitudes
(Gap and Aire sur l'Adour, France), in the tropics (Hyderabad, India)
and in the arctic (Kiruna, Sweden). So far the last two flights took
place in France and India in 1999. Analytical methods were improved
continuously. Today the most versatile instrument is a Varian SATURN
GC/MS system with ion trap detector, besides other systems with different
conventional detectors. The data base - soon available on this page -
includes all species of importance in stratospheric ozone chemistry.
Other activities today: investigations on volcanogenic gases and glacier
ice samples.
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