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| Titel |
Vertical mixing in atmospheric tracer transport models: error characterization and propagation |
| VerfasserIn |
C. Gerbig, S. Körner, J. C. Lin |
| 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 ; 8, no. 3 ; Nr. 8, no. 3 (2008-02-08), S.591-602 |
| Datensatznummer |
250005549
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| Publikation (Nr.) |
 copernicus.org/acp-8-591-2008.pdf |
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| Zusammenfassung |
| Imperfect representation of vertical mixing near the surface in atmospheric
transport models leads to uncertainties in modelled tracer mixing ratios.
When using the atmosphere as an integrator to derive surface-atmosphere
exchange from mixing ratio observations made in the atmospheric boundary
layer, this uncertainty has to be quantified and taken into account. A
comparison between radiosonde-derived mixing heights and mixing
heights derived from ECMWF meteorological data during May–June 2005 in
Europe revealed random discrepancies of about 40% for the daytime with
insignificant bias errors, and much larger values approaching 100% for
nocturnal mixing layers with bias errors also exceeding 50%. The
Stochastic Time Inverted Lagrangian Transport (STILT) model was used to
propagate this uncertainty into CO2 mixing ratio uncertainties,
accounting for spatial and temporal error covariance. Average values of 3 ppm
were found for the 2 month period, indicating that this represents a
large fraction of the overall uncertainty. A pseudo data experiment shows
that the error propagation with STILT avoids biases in flux retrievals when
applied in inversions. The results indicate that flux inversions employing
transport models based on current generation meteorological products have
misrepresented an important part of the model error structure likely leading
to biases in the estimated mean and uncertainties. We strongly recommend
including the solution presented in this work: better, higher resolution
atmospheric models, a proper description of correlated random errors, and
a modification of the overall sampling strategy. |
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