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| Titel |
CO2 dispersion modelling over Paris region within the CO2-MEGAPARIS project |
| VerfasserIn |
C. Lac, R. P. Donnelly, V. Masson, S. Pal, S. Riette, S. Donier, S. Queguiner, G. Tanguy, L. Ammoura, I. Xueref-Remy |
| 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 ; 13, no. 9 ; Nr. 13, no. 9 (2013-05-14), S.4941-4961 |
| Datensatznummer |
250018650
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| Publikation (Nr.) |
 copernicus.org/acp-13-4941-2013.pdf |
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| Zusammenfassung |
| Accurate simulation of the spatial and temporal variability of tracer mixing
ratios over urban areas is a challenging and interesting task needed to be
performed in order to utilise CO2 measurements in an atmospheric inverse
framework and to better estimate regional CO2 fluxes. This study
investigates the ability of a high-resolution model to simulate
meteorological and CO2 fields around Paris agglomeration during the March
field campaign of the CO2-MEGAPARIS project. The mesoscale atmospheric
model Meso-NH, running at 2 km horizontal resolution, is coupled with the
Town Energy Balance (TEB) urban canopy scheme and with the Interactions
between Soil, Biosphere and Atmosphere CO2-reactive (ISBA-A-gs) surface
scheme, allowing a full interaction of CO2 modelling between the surface
and the atmosphere. Statistical scores show a good representation of the
urban heat island (UHI) with stronger urban–rural contrasts on temperature
at night than during the day by up to 7 °C. Boundary layer heights
(BLH) have been evaluated on urban, suburban and rural sites during the
campaign, and also on a suburban site over 1 yr. The diurnal cycles of the
BLH are well captured, especially the onset time of the BLH increase and its
growth rate in the morning, which are essential for tall tower CO2
observatories. The main discrepancy is a small negative bias over urban and
suburban sites during nighttime (respectively 45 m and 5 m), leading to a
few overestimations of nocturnal CO2 mixing ratios at suburban sites and a
bias of +5 ppm. The diurnal CO2 cycle is generally well captured for all
the sites. At the Eiffel tower, the observed spikes of CO2 maxima occur
every morning exactly at the time at which the atmospheric boundary layer
(ABL) growth reaches the measurement height. At suburban ground stations,
CO2 measurements exhibit maxima at the beginning and at the end of each
night, when the ABL is fully contracted, with a strong spatio-temporal
variability. A sensitivity test without urban parameterisation removes the
UHI and underpredicts nighttime BLH over urban and suburban sites, leading to
large overestimation of nocturnal CO2 mixing ratio at the suburban sites
(bias of +17 ppm). The agreement between observation and prediction for BLH
and CO2 concentrations and urban–rural increments, both day and night,
demonstrates the potential of using the urban mesoscale system in the context
of inverse modelling |
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