In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 18, No. 22 ( 2018-11-22), p. 16553-16569
Abstract:
Abstract. 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.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-18-16553-2018
DOI:
10.5194/acp-18-16553-2018-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
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