References

ACP

Atmospheric Chemistry and Physics

ACP

Atmos. Chem. Phys.

1680-7324

Copernicus Publications

Göttingen, Germany

10.5194/acp-14-12553-2014

Analysis of elevated springtime levels of Peroxyacetyl nitrate (PAN) at the high Alpine research sites Jungfraujoch and Zugspitze

Pandey Deolal

¹ Henne

https://orcid.org/0000-0002-6637-4887

² Ries

³ Gilge

⁴ Weers

¹ Steinbacher

https://orcid.org/0000-0002-7195-8115

² Staehelin

https://orcid.org/0000-0001-7861-1889

¹ Peter

Institute for Atmospheric and Climate Science, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland

Laboratory for Air Pollution/Environmental Technology, Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland

Air Monitoring Network, Environment Agency Germany (UBA), Platform Zugspitze Schneefernerhaus (ZSF) of GAW-Global Station Zugspitze/Hohenpeissenberg, Germany

Hohenpeissenberg Meteorological Observatory, German Meteorological Service (DWD), Hohenpeissenberg, Germany

28 11 2014

14 22 12553 12571

2014

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://acp.copernicus.org/articles/14/12553/2014/acp-14-12553-2014.html

The full text article is available as a PDF file from https://acp.copernicus.org/articles/14/12553/2014/acp-14-12553-2014.pdf

The largest atmospheric peroxyacetyl nitrate (PAN) mole fractions at remote surface sites in the Northern Hemisphere are commonly observed during the months April and May. Different formation mechanisms for this seasonal maximum have previously been suggested: hemispheric-scale production from precursors accumulated during the winter months, increased springtime transport from up-wind continents or increased regional-scale production in the atmospheric boundary layer from recent emissions. The two high Alpine research sites Jungfraujoch (Switzerland) and Zugspitze (Germany) exhibit a distinct and consistent springtime PAN maximum. Since these sites intermittently sample air masses of free-tropospheric and boundary layer origin, they are ideally suited to identify the above-mentioned PAN formation processes and attribute local observations to these. Here we present a detailed analysis of PAN observations and meteorological conditions during May 2008 when PAN levels were especially elevated at both sites. The highest PAN concentrations were connected with anticyclonic conditions, which persisted in May 2008 for about 10 days with north-easterly advection towards the sites. A backward dispersion model analysis showed that elevated PAN concentrations were caused by the combination of favourable photochemical production conditions and large precursor concentrations in the European atmospheric boundary layer. The results suggest that the largest PAN values in spring 2008 at both sites were attributable to regional-scale photochemical production of PAN in the (relatively cold) planetary boundary layer from European precursors, whereas the contribution of inter-continental transport or free-tropospheric build-up was of smaller importance for these sites.

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