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| Titel |
Comparing atmospheric transport models for future regional inversions over Europe – Part 1: mapping the atmospheric CO2 signals |
| VerfasserIn |
C. Geels, M. Gloor, P. Ciais, P. Bousquet, P. Peylin, A. T. Vermeulen, R. Dargaville, T. Aalto, J. Brandt, J. H. Christensen, L. M. Frohn, L. Haszpra, U. Karstens, C. Rödenbeck, M. Ramonet, G. Carboni, R. Santaguida |
| 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 ; 7, no. 13 ; Nr. 7, no. 13 (2007-07-02), S.3461-3479 |
| Datensatznummer |
250005117
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| Publikation (Nr.) |
 copernicus.org/acp-7-3461-2007.pdf |
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| Zusammenfassung |
The CO2 source and sink distribution across Europe can be
estimated in principle through inverse methods by combining CO2
observations and atmospheric transport models. Uncertainties of such
estimates are mainly due to insufficient spatiotemporal coverage of
CO2 observations and biases of the models. In order to assess the
biases related to the use of different models the CO2
concentration field over Europe has been simulated with five
different Eulerian atmospheric transport models as part of the
EU-funded AEROCARB project, which has the main goal to estimate the
carbon balance of Europe. In contrast to previous comparisons, here
both global coarse-resolution and regional higher-resolution models
are included. Continuous CO2 observations from continental,
coastal and mountain sites as well as flasks sampled on aircrafts
are used to evaluate the models' ability to capture the
spatiotemporal variability and distribution of lower troposphere
CO2 across Europe. 14CO2 is used in addition to
evaluate separately fossil fuel signal predictions. The simulated
concentrations show a large range of variation, with up to ~10 ppm higher surface concentrations over Western and Central Europe in
the regional models with highest (mesoscale) spatial resolution.
The simulation – data comparison reveals that generally
high-resolution models are more successful than coarse models in
capturing the amplitude and phasing of the observed short-term
variability. At high-altitude stations the magnitude of the
differences between observations and models and in between models is
less pronounced, but the timing of the diurnal cycle is not well
captured by the models.
The data comparisons show also that the timing of the observed
variability on hourly to daily time scales at low-altitude stations
is generally well captured by all models. However, the amplitude of
the variability tends to be underestimated. While daytime values are
quite well predicted, nighttime values are generally underpredicted.
This is a reflection of the different mixing regimes during day and
night combined with different vertical resolution between models. In
line with this finding, the agreement among models is increased when
sampling in the afternoon hours only and when sampling the mixed
portion of the PBL, which amounts to sampling at a few hundred
meters above ground. The main recommendations resulting from the
study for constraining land carbon sources and sinks using
high-resolution concentration data and state-of-the art transport
models through inverse methods are given in the following: 1) Low
altitude stations are presently preferable in inverse studies. If
high altitude stations are used then the model level that represents
the specific sites should be applied, 2) at low altitude sites only
the afternoon values of concentrations can be represented
sufficiently well by current models and therefore afternoon values
are more appropriate for constraining large-scale sources and sinks in
combination with transport models, 3) even when using only afternoon
values it is clear that data sampled several hundred meters above
ground can be represented substantially more robustly in models than
surface station records, which emphasize the use of tower data in
inverse studies and finally 4) traditional large scale transport
models seem not sufficient to resolve fine-scale features associated
with fossil fuel emissions, as well as larger-scale features like
the concentration distribution above the south-western Europe. It is
therefore recommended to use higher resolution models for
interpretation of continental data in future studies. |
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