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| Titel |
The diurnal evolution of the urban heat island of Paris: a model-based case study during Summer 2006 |
| VerfasserIn |
H. Wouters, K. Ridder, M. Demuzere, D. Lauwaet, N. P. M. Lipzig |
| 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. 17 ; Nr. 13, no. 17 (2013-09-02), S.8525-8541 |
| Datensatznummer |
250085656
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| Publikation (Nr.) |
 copernicus.org/acp-13-8525-2013.pdf |
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| Zusammenfassung |
| The urban heat island (UHI) over Paris during summer 2006 was simulated using
the Advanced Regional Prediction System (ARPS) updated with a simple urban
parametrization at a horizontal resolution of 1 km. Two integrations were
performed, one with the urban land cover of Paris and another in which Paris
was replaced by cropland. The focus is on a five-day clear-sky period, for
which the UHI intensity reaches its maximum. The diurnal evolution of the UHI
intensity was found to be adequately simulated for this five day period. The
maximum difference at night in 2 m temperature between urban and rural areas
stemming from the urban heating is reproduced with a relative error of less
than 10%. The UHI has an ellipsoidal shape and stretches along the
prevailing wind direction. The maximum UHI intensity of 6.1 K occurs at
23:00 UTC located 6 km downstream of the city centre and this largely
remains during the whole night. An idealized one-column model study
demonstrates that the nocturnal differential sensible heat flux, even though
much smaller than its daytime value, is mainly responsible for the maximum
UHI intensity. The reason for this nighttime maximum is that additional heat
is only affecting a shallow layer of 150 m. An air uplift is explained by
the synoptic east wind and a ramp upwind of the city centre, which leads to a
considerable nocturnal adiabatic cooling over cropland. The idealized study
demonstrates that the reduced vertical adiabatic cooling over the city
compared to cropland induces an additional UHI build-up of 25%. The UHI
and its vertical extent is affected by the boundary-layer stability,
nocturnal low-level jet as well as radiative cooling. Therefore, improvements
of representing these boundary-layer features in atmospheric models are
important for UHI studies. |
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