0000000001279047
AUTHOR
Thibaut Vairet
Intégration d’un modèle de développement urbain dans un modèle de simulation climatique urbain
National audience
How relevant are local climate zones and urban climate zones for urban climate research? Dijon (France) as a case study.
17 pages; International audience; Several typologies of urban surface properties have been proposed, in recent years, for urban heat island studies and climate modeling. Some were specifically developed for cities and urban climate issues, like the Urban Climate Zones, and the more recent Local Climate Zones. The initial objective of this paper is to evaluate the capacity of these two typologies to identify thermal environments in and around cities, and to determine which typology best captures the daily spatio-temporal patterns of surface and urban canopy heat islands. To simulate urban climate with a model, LULC data based on a given typology are required. To avoid circularity, we combine…
Évaluation des effets thermiques des leviers d'action visant à réduire l'îlot de chaleur urbain : l'exemple de Dijon.
Climate Change and Urban Heat Island (UHI) combine their effects and lead to increased frequencies and intensities of heat waves in urban environments. Considering the associated public health issues, several actions are possible: the color of the materials, the development of water surfaces or urban vegetation. In Dijon, a network of 60 stations makes it possible to evaluate the potential of these three actions. Analysis of the warm summer 2016 season reveals that the refreshing role of water only occurs during daytime, the effect of bright surfaces (concrete versus bitumen) on the air temperature is only a few tenths of a degree, while vegetation offers the largest refreshing potential. I…
Sensitivity of a climate model to urban form : application on Dijon Métropole
The urban environment is at the crossroads of two complex systems with different temporalities : climate and society. The urban climate is a modification of the climate caused by the presence of a city. The most successful expression of this climate change by the presence of the city is the phenomenon of Urban Heat Island (UHI). In a global context of adaptation and mitigation to climate change and urban development, this phenomenon of ICU tends to increase, and its health impacts on populations to become more prominent. This work is aimed at improving the knowledge of the impact of urban form and urban development on the intensity of the UCI through the implementation of a decision support…
Urban Heat Island (UHI) and heat waves: what relations?
With four years of measurements and alarge sample of stations, the MUSTARDijon network allows for a detailed characterization of the Urban HeatIsland (UHI), a warm season phenomenon. But UHI and maximum temperature values are out of phase at twodistinct time-scales. Seasonally, the maxima of UHI occur from May to July, i.e. before the annual peak oftemperature (July to August). At a daily time-scale, analysis of the two heat waves of July 2015 shows a lag of afew days between the peak of UHI and the heat wave. Two hypotheses are suggested to explain these lags:changes in radiative conditions and/or energy fluxes between the ground surface and the atmosphere.
Les Local Climate Zones face à la canicule de 2018 à Dijon.
Air temperatures measured by the MUSTARDijon network are analyzed during the summer 2018 (July 24 - August 8) heat wave. The WUDAPT method is applied to Dijon to identify Local Climate Zones (LCZs). Diurnal rhythms and nighttime mean temperatures are analyzed according to LCZs as well as to altitude and distance to the city center. During warm nights, altitude plays a negligible role. The temperatures depend to the distance of the city center. They are also associated to the anthropization summarized by the LCZs. Form of the building and vegetation are the two keys to understand and modulate the night temperatures which have the greatest impact on human health during heat waves.
Formes urbaines et ilots de chaleurs : simulations et outils d'aide à la décision pour une ville durable
National audience; Le monde s’urbanise. Selon les nations unies, plus d’un humain sur deux réside en milieu urbain et un septième de la population habite une agglomération millionnaire. Il s’agit d’une des mutations majeures de l’époque contemporaine. Chaque ville possède des caractéristiques propres (humaines, morphologiques...) mais l’Îlot de Chaleur Urbain (ICU) apparaît comme un phénomène inhérent et commun à toutes. En août 2003, l’Europe a subi une périodeestivale caniculaire ayant causé la mort de plus de 70 000 personnes dont 20 000 uniquement en France (Robine et al, 2008).