Global analysis of halogenated trace gases in the UTLS: from long-lived to short-lived substances

• Main Author: Jesswein, Markus
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2024
• Subjects: ddc:550; Antarctic; The Antarctic; Pacific; Antarc*
• Online Access: http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/81395; https://nbn-resolving.org/urn:nbn:de:hebis:30:3-813956; https://doi.org/10.21248/gups.81395; http://publikationen.ub.uni-frankfurt.de/files/81395/Thesis_jesswein_upload.pdf

In this dissertation, the distribution of chlorinated and brominated substances in the upper troposphere and lower stratosphere is investigated. These substances contribute significantly to the catalytic decomposition of ozone and are involved in the recurrent formation of the polar ozone hole in the Antarctic winter and spring. The Montreal Protocol, a multilateral environmental treaty to protect the ozone layer, has successfully reduced emissions of long-lived chlorine- and bromine-containing substances. Short-lived chlorinated and brominated substances, some of which are natural and anthropogenic in origin, are not regulated by the Montreal Protocol and it can be assumed that their relative contribution to the stratospheric halogen budget will increase, while the contribution of long-lived compounds will steadily decrease. The distribution of long- and short-lived halogenated substances are part of current research. For the upper troposphere and lower stratosphere, the very short-lived substances are particularly important. The lower stratosphere needs special investigation in this respect, since its composition is influenced by different transport processes. The influences on ozone trends in the lower stratosphere are subject to great uncertainties. Especially in the Southern Hemisphere, the number of observations is very limited. In this work, the GhOST (Gas chromatograph for Observational Studies using Tracers) instrument was used during the SouthTRAC measurement campaign on the German HALO (High Altitude and LOng range) research aircraft, providing observations of halogenated hydrocarbons in Antarctic late winter to early spring 2019, a generally poorly sampled region. The polar vortex was, compared to previous years, significantly weaker and shifted towards the eastern South Pacific and South America. From the airborne measurements of chlorinated source gases, inorganic chlorine (the sum of active chlorine and reservoir gases; Cly) could be inferred with the result that Cly within the vortex increased up ...