TY  - JOUR
A1  - Schuck, Tanja J.
A1  - Lefrancois, Fides
A1  - Gallmann, Franziska
A1  - Wang, Danrong
A1  - Jesswein, Markus
A1  - Hoker, Jesica
A1  - Bönisch, Harald
A1  - Engel, Andreas
T1  - Establishing long-term measurements of halocarbons at Taunus Observatory
T2  - Atmospheric chemistry and physics
N2  - In late 2013, a whole air flask collection programme was started at Taunus Observatory (TO) in central Germany. Being a rural site in close proximity to the Rhine–Main area, Taunus Observatory allows assessment of emissions from a densely populated region. Owing to its altitude of 825 m, the site also regularly experiences background conditions, especially when air masses approach from north-westerly directions. With a large footprint area mainly covering central Europe north of the Alps, halocarbon measurements at the site have the potential to improve the database for estimation of regional and total European halogenated greenhouse gas emissions. Flask samples are collected weekly for offline analysis using a GC/MS system simultaneously employing a quadrupole as well as a time-of-flight mass spectrometer. As background reference, additional samples are collected approximately once every 2 weeks at the Mace Head Atmospheric Research Station (MHD) when air masses approach from the site's clean air sector. Thus the time series at TO can be linked to the in situ AGAGE measurements and the NOAA flask sampling programme at MHD. An iterative baseline identification procedure separates polluted samples from baseline data. While there is good agreement of baseline mixing ratios between TO and MHD, with a larger variability of mixing ratios at the continental site, measurements at TO are regularly influenced by elevated halocarbon mixing ratios. Here, first time series are presented for CFC-11, CFC-12, HCFC-22, HFC-134a, HFC-227ea, HFC-245fa, and dichloromethane. While atmospheric mixing ratios of the chlorofluorocarbons (CFCs) decrease, they increase for the hydrochlorofluorocarbons (HCFCs) and the hydrofluorocarbons (HFCs). Small unexpected differences between CFC-11 and CFC-12 are found with regard to frequency and relative enhancement of high mixing ratio events and seasonality, although production and use of both compounds are strictly regulated by the Montreal Protocol, and therefore a similar decrease in atmospheric mixing ratios should occur. Dichloromethane, a solvent about which recently concerns have been raised regarding its growing influence on stratospheric ozone depletion, does not show a significant trend with regard to both baseline mixing ratios and the occurrence of pollution events at Taunus Observatory for the time period covered, indicating stable emissions in the regions that influence the site. An analysis of trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model reveals differences in halocarbon mixing ranges depending on air mass origin.
Y1  - 2018
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/49196
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-491968
SN  - 1680-7324
N1  - © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License.
VL  - 18
IS  - 22
SP  - 16553
EP  - 16569
PB  - EGU
CY  - Katlenburg-Lindau
ER  -