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| Titel |
Impact of transatlantic transport episodes on summertime ozone in Europe |
| VerfasserIn |
G. Guerova, I. Bey, J.-L. Attié, R. V. Martin, J. Cui, M. Sprenger |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 6, no. 8 ; Nr. 6, no. 8 (2006-06-20), S.2057-2072 |
| Datensatznummer |
250003919
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| Publikation (Nr.) |
 copernicus.org/acp-6-2057-2006.pdf |
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| Zusammenfassung |
| This paper reports on the transport of ozone (O3) and related species over
the North Atlantic ocean and its impact on Europe. Measurements of nitrogen
dioxide (NO2) and carbon monoxide (CO) columns from the GOME and MOPITT
satellite instruments, respectively, are used in conjunction with the
GEOS-CHEM global model of transport and tropospheric chemistry to identify
the major events of long range transport that reach Europe over the course of
summer 2000. Sensitivity model simulations are used to analyse observed O3
distributions with respect to the impact of long range transport events. For
that purpose, we used in-situ O3 observations taken at the mountain site of
Jungfraujoch as well as O3 vertical profiles taken in the vicinity of
central European cities. Over the course of summer 2000, we identified 9
major episodes of transatlantic pollution transport; 7 events are associated
with transient cyclones while 2 events occur through zonal transport (e.g. by
advection in the strong low-level westerly winds established in summer
between the Azores anticyclone and transient cyclones). We find that on
average three episodes occur per month with the strongest ones being in June.
The number and frequency of long range transport events that reach Europe are
driven by the position and strength of the Azores anticyclone. Model
sensitivity simulations indicate that the summer mean North American O3
contribution ranges from 3 to 5 ppb (7–11%) in the planetary boundary layer
and 10 to 13 ppb (18–23%) in the middle and upper troposphere. During
particular episodes, North American sources can result in O3 enhancements up
to 25–28 ppb in the layer between 800–600 hPa and 10–12 ppb in the boundary
layer. The impact of the zonal transport events on O3 distribution over
Europe is more clearly seen below 700 hPa as they tend to transport pollution
at lower levels while the events associated with transient cyclones are more
likely to have an impact on the middle and upper troposphere (i.e. above 600 hPa).
The air mass origins found in the GEOS-CHEM model are clearly confirmed
by back trajectory analyses. During most of the 9 events, a strong
contribution in North American O3 is in general associated with only little
European O3 and vice-versa (in particular at the Jungfraujoch). A
substantial North American contribution (e.g., 30% or higher) to O3 over
Europe does not always result in pronounced O3 enhancements in the
observations during our period of study. |
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