Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 12421-12447, 2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
19 Oct 2017
The influence of mid-latitude cyclones on European background surface ozone
K. Emma Knowland1,2, Ruth M. Doherty3, Kevin I. Hodges4, and Lesley E. Ott2 1Universities Space Research Association (USRA)/Goddard Earth Science Technology & Research (GESTAR), Columbia, Maryland, USA
2Global Modeling and Assimilation Office (GMAO), NASA Goddard Space Flight Center (GSFC), Greenbelt, Maryland, USA
3School of Geosciences, University of Edinburgh, Edinburgh, UK
4Dept. of Meteorology, University of Reading, Reading, UK
Abstract. The relationship between springtime mid-latitude cyclones and background ozone (O3) is explored using a combination of observational and reanalysis data sets. First, the relationship between surface O3 observations at two rural monitoring sites on the west coast of Europe – Mace Head, Ireland, and Monte Velho, Portugal – and cyclone track frequency in the surrounding regions is examined. Second, detailed case study examination of four individual mid-latitude cyclones and the influence of the associated frontal passage on surface O3 is performed. Cyclone tracks have a greater influence on the O3 measurements at the more northern coastal European station, Mace Head, located within the main North Atlantic (NA) storm track. In particular, when cyclones track north of 53° N, there is a significant relationship with high levels of surface O3 (> 75th percentile). The further away a cyclone is from the NA storm track, the more likely it will be associated with both high and low (< 25th percentile) levels of O3 at the observation site during the cyclone's life cycle. The results of the four case studies demonstrate (a) the importance of the passage of a cyclone's cold front in relation to surface O3 measurements, (b) the ability of mid-latitude cyclones to bring down high levels of O3 from the stratosphere, and (c) that accompanying surface high-pressure systems and their associated transport pathways play an important role in the temporal variability of surface O3. The main source of high O3 to these two sites in springtime is from the stratosphere, either from direct injection into the cyclone or associated with aged airstreams from decaying downstream cyclones that can become entrained and descend toward the surface within new cyclones over the NA region.

Citation: Knowland, K. E., Doherty, R. M., Hodges, K. I., and Ott, L. E.: The influence of mid-latitude cyclones on European background surface ozone, Atmos. Chem. Phys., 17, 12421-12447,, 2017.
Publications Copernicus
Short summary
First study to our knowledge to quantify the influence extratropical cyclones have on the temporal variability of springtime surface ozone (O3) measured on the west coast of Europe when cyclones are nearby. We show passing cyclones have a discernible influence on surface O3 concentrations. In-depth findings from four case studies, using a combination of reanalyses and a modeled tracer, demonstrate there are several transport pathways before O3-rich air eventually reaches the surface.
First study to our knowledge to quantify the influence extratropical cyclones have on the...