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| Titel |
Global multi-year O3-CO correlation patterns from models and TES satellite observations |
| VerfasserIn |
A. Voulgarakis, P. J. Telford, A. M. Aghedo, P. Braesicke, G. Faluvegi, N. L. Abraham, K. W. Bowman, J. A. Pyle, D. T. Shindell  |
| 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 ; 11, no. 12 ; Nr. 11, no. 12 (2011-06-22), S.5819-5838 |
| Datensatznummer |
250009860
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| Publikation (Nr.) |
 copernicus.org/acp-11-5819-2011.pdf |
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| Zusammenfassung |
| The correlation between measured tropospheric ozone (O3) and carbon
monoxide (CO) has been used extensively in tropospheric chemistry studies to
explore the photochemical characteristics of different regions and to
evaluate the ability of models to capture these characteristics. Here, we
present the first study that uses multi-year, global, vertically resolved,
simultaneous and collocated O3 and CO satellite (Tropospheric Emission
Spectrometer) measurements, to determine this correlation in the middle/lower
free troposphere for two different seasons, and to evaluate two
chemistry-climate models. We find results that are fairly robust across
different years, altitudes and timescales considered, which indicates that
the correlation maps presented here could be used in future model
evaluations. The highest positive correlations (around 0.8) are found in the
northern Pacific during summer, which is a common feature in the observations
and the G-PUCCINI model. We make quantitative comparisons between the models
using a single-figure metric (C), which we define as the correlation
coefficient between the modeled and the observed O3-CO correlations for
different regions of the globe. On a global scale, the G-PUCCINI model shows
a good performance in the summer (C=0.71) and a satisfactory
performance in the winter (C=0.52). It captures midlatitude features
very well, especially in the summer, whereas the performance in regions like
South America or Central Africa is weaker. The UKCA model
(C=0.46/0.15 for July–August/December–January on a global scale)
performs better in certain regions, such as the tropics in winter, and it
captures some of the broad characteristics of summer extratropical
correlations, but it systematically underestimates the O3-CO correlations
over much of the globe. It is noteworthy that the correlations look very
different in the two models, even though the ozone distributions are similar.
This demonstrates that this technique provides a powerful global constraint
for understanding modeled tropospheric chemical processes. We investigated
the sources of the correlations by performing a series of sensitivity
experiments. In these, the sign of the correlation is, in most cases,
insensitive to removing different individual emissions, but its magnitude
changes downwind of emission regions when applying such perturbations.
Interestingly, we find that the O3-CO correlation does not solely reflect
the strength of O3 photochemical production, as often assumed by earlier
studies, but is more complicated and may reflect a mixture of different
processes such as transport. |
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