FASTOF: Fully automated in-situ GC-TOF Observation of atmospheric trace gases

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Halocarbon compounds play an essential role in atmospheric chemistry, in the depletion ofstratospheric ozone and in radiative forcing of the atmosphere. They are most commonlymeasured by gas chromatography coupled to quadrupole mass spectrometry. We propose todevelop a novel measurement system, in which the quadrupole mass spectrometer is replacedby a much more powerful time-of-flight mass spectrometer, which has recently becomeavailable in a form which is suited for field deployment. The main advantage of this newlyavailable mass spectrometer is that it achieves the sensitivity of a quadrupole massspectrometer which is tuned to a single mass, but in the same time provides information on allmasses (full scan mode). We suggest to fully automate this instrument in order to be able todeploy it at remote field sites. First atmospheric observations will already be possible at anearly stage of the instrument development, while fully automated measurement capability willbe available after the second project year.We suggest three scientific areas for the first measurements with this instrument, focussing onhalogenated hydrocarbons in the atmosphere: (i) measure brominated and iodinatedhalocarbons which may impact stratospheric ozone in their source region, the marineboundary layer, (ii) use the scanning capability of the instrument to search for new, so farunidentified halocarbons in the atmosphere and (iii) measure hydrofluorocarbons, which couldbecome much more important greenhouse gases in the future and use the scanning capabilitiesof the TOF mass spectrometer in order to create an air archive allowing to quantify so farunidentified species, even at a later stage.With the work proposed here we would like to establish the GC-TOF technique foratmospheric trace gas measurements, which will provide much more detailed information inthe future. Many further applications of this instrument in national and international projectsare foreseeable, e.g. for studies of non-CO2 greenhouse gases and ozone depleting chemicals,their atmospheric trends, sinks and sources, distributions, variabilities and their impact onchemistry and climate of the atmosphere.