scholarly journals Une simulation des interactions ville-atmosphère à différentes échelles : application sur Strasbourg

Climatologie ◽  
2015 ◽  
Vol 12 ◽  
pp. 44-64
Author(s):  
Pierre P. Kastendeuch ◽  
Georges Najjar
Keyword(s):  

Plusieurs modèles météorologiques ont été utilisés pour simuler les interactions ville-atmosphère à différentes échelles. Cette chaîne de simulation implique l’utilisation de réanalyses globales d’une résolution de 16 km comme données de forçage météorologique. Ce forçage est utilisé pour contraindre un modèle de méso-échelle qui permet d’atteindre une résolution de 250 m sur la ville grâce à la technique du grid-nesting. Finalement les champs du modèle à 250 m ont été utilisés comme forçage météorologique pour un modèle de simulation de canopée urbaine en 3D qui fonctionne avec une résolution de quelques mètres. Les outils utilisés pour atteindre cet objectif sont : les réanalyses du CEPMMT, le modèle Méso-NH & SURFEX (de Météo-France et du Laboratoire d’Aérologie) et le modèle de canopée urbaine LASER/F (Icube). Une simulation a été réalisée sur Strasbourg pour tester cette chaîne sur une période qui va du 13 au 17 août 2002. Les validations montrent que les processus de surface et atmosphériques simulés par Méso-NH & SURFEX pour la résolution de 250 m sont en accord avec les mesures de terrain. Pour s’assurer que le modèle de canopée urbaine en 3D s’intègre bien dans la chaîne de simulation, ses résultats sont comparés à ceux de SURFEX pour un quartier. Les analyses montrent que les résultats obtenus par ce modèle sont en accord avec ceux de SURFEX. L’introduction de la géométrie réelle du quartier en 3D permet même un gain appréciable pour certaines variables. Vu la cohérence des résultats obtenus, l’adjonction du modèle de canopée urbaine se justifie dans cette chaîne. Et ceci d’autant plus que ce type de modèle permet l’accès à de nouvelles informations avec un haut niveau de détails.

2002 ◽  
Author(s):  
Jane M. Smith ◽  
S. J. Smith
Keyword(s):  

2006 ◽  
Vol 7 ◽  
pp. 247-250 ◽  
Author(s):  
N. Söhne ◽  
J.-P. Chaboureau ◽  
S. Argence ◽  
D. Lambert ◽  
E. Richard

Abstract. An objective evaluation of mesoscale simulations by the model-to-satellite approach is performed. The model-to-satellite approach consists in calculating brightness temperatures (BT) from model variables with a radiative transfer code. It allows to compare directly and quantitatively simulations and observations by calculating statistical scores. This method is detailed and used herein to objectively evaluate an ensemble of Meso-NH simulations of the Algiers 2001 flash flood. In particular, the improvement due to the grid-nesting is shown.


2019 ◽  
Vol 11 (12) ◽  
pp. 4352-4376 ◽  
Author(s):  
Xin‐Zhong Liang ◽  
Qi Li ◽  
Haixia Mei ◽  
Mingjian Zeng
Keyword(s):  

2005 ◽  
Vol 62 (9) ◽  
pp. 3232-3249 ◽  
Author(s):  
Gregory J. Tripoli

Abstract This paper presents the results of a series of idealized cloud resolving simulations of the evolution of moist roll convection observed as part of the Lake-Induced Convection Experiment (Lake-ICE) that took place during the 1997/98 winter over central Lake Michigan. Satellite and radar observations of the roll convection depict striking linear rolls stretching from 10 km off the western shore of the lake, across to the eastern shore, and then continuing across Michigan. The spacing of the primary rolls was observed to be 6 km, giving a ratio of spacing to depth of about 5:1, which is consistent with theory. In addition, a longer wavelength (13 km) of stationary banding was observed parallel to the shoreline. In an earlier study of this case, multiply nested simulations of the convective rolls based on real data variable initialization were successful in producing banded structures with similar spacing and location over the water to those observed using fine grid resolution of about 500 m. Unfortunately, the initial locations of simulated bands were organized primarily by numerical effects of grid interpolation. This suggested that the spacing of the bands was robust, but that their initial location was highly sensitive to subtle systematic forcings. In this paper, a set of idealized model experiments, designed to isolate the role that physically realistic local forcing plays in the organization of the rolls, was performed. Because externally generated upstream turbulence was suppressed in these tests so as not to bias the result, the generation of rolls was delayed until 20–30 km downwind of the observed location and the location simulated in the previous grid nesting experiments. It was shown that the subtle effects of the shoreline geometry were sufficient to spawn a near-surface streamwise vorticity that became the primary seed for roll development at the most efficient mode of roll convection. These results suggest that previous structures evolved in the upstream shear-driven land-based mixed layer were likely also important in determining where the nonlocal overturning was first triggered. It is not clear from these results whether the shear-driven structures that evolved over the land also played a significant role in organizing the structural geometry of the lake rolls. Results also suggested that the shore parallel bands were a robust feature of the atmospheric structure resulting from resonant gravity wave trapping in the frontal layer.


2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Igor Litvinchev ◽  
Edith Lucero Ozuna Espinosa

A problem of packing a limited number of unequal circles in a fixed size rectangular container is considered. The aim is to maximize the (weighted) number of circles placed into the container or minimize the waste. This problem has numerous applications in logistics, including production and packing for the textile, apparel, naval, automobile, aerospace, and food industries. Frequently the problem is formulated as a nonconvex continuous optimization problem which is solved by heuristic techniques combined with local search procedures. New formulations are proposed for approximate solution of packing problem. The container is approximated by a regular grid and the nodes of the grid are considered as potential positions for assigning centers of the circles. The packing problem is then stated as a large scale linear 0-1 optimization problem. The binary variables represent the assignment of centers to the nodes of the grid. Nesting circles inside one another is also considered. The resulting binary problem is then solved by commercial software. Numerical results are presented to demonstrate the efficiency of the proposed approach and compared with known results.


2014 ◽  
Vol 57 (3) ◽  
pp. 355-368 ◽  
Author(s):  
JIANG Wen-Bin ◽  
LIN Mian ◽  
LI Yong ◽  
FAN Feng-Xin ◽  
YAN Jun

1996 ◽  
Vol 80 (1-2) ◽  
pp. 167-202 ◽  
Author(s):  
Peter P. Sullivan ◽  
James C. McWilliams ◽  
Chin-Hoh Moeng

2000 ◽  
Vol 72 (2-4) ◽  
pp. 203-221 ◽  
Author(s):  
J. Stein ◽  
E. Richard ◽  
J. P. Lafore ◽  
J. P. Pinty ◽  
N. Asencio ◽  
...  

2021 ◽  
Vol 14 (6) ◽  
pp. 3317-3333
Author(s):  
Tobias Gronemeier ◽  
Kerstin Surm ◽  
Frank Harms ◽  
Bernd Leitl ◽  
Björn Maronga ◽  
...  

Abstract. We demonstrate the capability of the PALM model system version 6.0 to simulate neutrally stratified urban boundary layers. Our simulation uses the real-world building configuration of the HafenCity area in Hamburg, Germany. Using PALM's virtual measurement module, we compare simulation results to wind-tunnel measurements of a downscaled replica of the study area. Wind-tunnel measurements of mean wind speed agree within 5 % on average while the wind direction deviates by approximately 4∘. Turbulence statistics similarly agree. However, larger differences between measurements and simulation arise in the vicinity of surfaces where building geometry is insufficiently resolved. We discuss how to minimize these differences by improving the grid layout and give tips for setup preparation. Also, we discuss how existing and upcoming features of PALM like the grid nesting and immersed boundary condition help improve the simulation results.


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