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| Titel |
Atmospheric transport and chemistry of trace gases in LMDz5B: evaluation and implications for inverse modelling |
| VerfasserIn |
R. Locatelli, P. Bousquet, F. Hourdin, M. Saunois, A. Cozic, F. Couvreux, J.-Y. Grandpeix, M.-P. Lefebvre, C. Rio, P. Bergamaschi, S. D. Chambers, U. Karstens, V. Kazan, S. van der Laan, H. A. J. Meijer, J. Moncrieff, M. Ramonet, H. A. Scheeren, C. Schlosser, M. Schmidt, A. Vermeulen, A. G. Williams |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 2 ; Nr. 8, no. 2 (2015-02-03), S.129-150 |
| Datensatznummer |
250116102
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| Publikation (Nr.) |
 copernicus.org/gmd-8-129-2015.pdf |
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| Zusammenfassung |
Representation of atmospheric transport is a major source of error in the
estimation of greenhouse gas sources and sinks by inverse modelling. Here we
assess the impact on trace gas mole fractions of the new physical
parameterizations recently implemented in the atmospheric global climate
model LMDz to improve vertical diffusion, mesoscale mixing by thermal plumes
in the planetary boundary layer (PBL), and deep convection in the
troposphere. At the same time, the horizontal and vertical resolution of the
model used in the inverse system has been increased. The aim of this paper is
to evaluate the impact of these developments on the representation of trace
gas transport and chemistry, and to anticipate the implications for
inversions of greenhouse gas emissions using such an updated model.
Comparison of a one-dimensional version of LMDz with large eddy simulations
shows that the thermal scheme simulates shallow convective tracer transport
in the PBL over land very efficiently, and much better than previous versions
of the model. This result is confirmed in three-dimensional simulations, by a
much improved reproduction of the radon-222 diurnal cycle. However, the
enhanced dynamics of tracer concentrations induces a stronger sensitivity of
the new LMDz configuration to external meteorological forcings. At larger
scales, the inter-hemispheric exchange is slightly slower when using the new
version of the model, bringing them closer to observations. The increase in
the vertical resolution (from 19 to 39 layers) significantly improves the
representation of stratosphere/troposphere exchange. Furthermore, changes in
atmospheric thermodynamic variables, such as temperature, due to changes in
the PBL mixing modify chemical reaction rates, which perturb chemical
equilibriums of reactive trace gases.
One implication of LMDz model
developments for future inversions of greenhouse gas emissions is the ability
of the updated system to assimilate a larger amount of high-frequency data
sampled at high-variability stations. Others implications are discussed at
the end of the paper. |
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