A model study of the January 2006 low total ozone episode over Western Europe and comparison with ozone sonde data 1Royal Meteorological Institute of Belgium, Brussels, Belgium
2Research Centre Jülich, Institute for Chemistry and Dynamics of the Geosphere 1: Stratosphere, Jülich, Germany
3Research Centre Karlsruhe, Institute for Meteorology and Climate Research, IMK, Karlsruhe, Germany
Received: 01 Dec 2008 – Published in Atmos. Chem. Phys. Discuss.: 05 Mar 2009 – Published: 08 Sep 2009Abstract. Total column and stratospheric ozone levels at mid-latitudes often
reveal strong fluctuations on time scales of days caused by dynamic
processes. In some cases the total ozone column is distinctly reduced
below climatological values. Here, a very low total ozone episode
around 19 January 2006 over Western Europe is investigated when the
observed total ozone column over Uccle (BE), measured by a Brewer
spectrophotometer, reached a daily minimum of 200 DU, the
lowest recorded value at this station. In order to investigate the
mechanisms leading to the ozone minimum, the present study used data
from (i) six ozone sounding stations in Western and Middle Europe,
(ii) ECMWF meteorological fields, (iii) a simulation of the CLaMS
model for January 2006, (iv) a multi-year run of the chemistry
transport model KASIMA, and (v) a six-year run of the climate
chemistry model ECHAM5/MESSy1. The ozone decrease at different heights
was quantified and it was determined to what extent different
transport mechanisms, and instantaneous, in-situ chemical ozone
depletion contributed to the event. All three models reproduced
the evolution and formation of the event. The ozone column decrease
between Θ=300 and 750 K was strongest at Uccle (BE)
and De Bilt (NL) with 108 and 103 DU, respectively, and
somewhat lower at Hohenpeissenberg (DE), Payerne (CH), Prague (CZ) and
Lerwick (UK) with 85, 84, 83 and 74 DU, respectively.
This analysis demonstrated that mainly the displacement of the ozone
depleted polar vortex contributed to the ozone column decrease.
Advection of ozone-poor low-latitude air masses was important in the
UTLS region. The vertical displacement of isentropes connected with
divergence of air out of the column was found to be of minor importance
compared to the horizontal transport processes. Severe low total ozone
episodes seem to occur when the mentioned mechanisms are superimposed.
Instantaneous, in-situ chemical ozone depletion accounted for only
2±1% of the overall total ozone decrease at the sounding stations.
Citation: Mangold, A., Grooß, J.-U., De Backer, H., Kirner, O., Ruhnke, R., and Müller, R.: A model study of the January 2006 low total ozone episode over Western Europe and comparison with ozone sonde data, Atmos. Chem. Phys., 9, 6429-6451, doi:10.5194/acp-9-6429-2009, 2009.