INFLUENCE OF THE INTERACTIONS OF LOCAL DYNAMICAL PROCESSES WITH LARGE-SCALE FLOW ON AIR QUALITY IN THE GRENOBLE AREA

The vertical distribution of ozone over the Grenoble area is investigated for two summer smog episodes in 1999 and 2003. The effects of the interactions of local dynamical processes with large-scale circulations were estimated using numerical modelling. The results suggest that a terrain-induced shear layer above the boundary layer confines pollutants within the valley. Vertical exchanges through this shear layer have a considerable influence on the near-surface ozone concentration from day to day

Estimation of urban sensible heat flux using a dense wireless network of observations

The determination of the sensible heat flux over urban terrain is challenging due to irregular surface geometry and surface types. To address this, in 2006-07, a major field campaign (LUCE) took place at the École Polytechnique Fédérale de Lausanne campus, a moderately occupied urban site. A distributed network of 92 wireless weather stations was combined with routine atmospheric profiling, offering high temporal and spatial resolution meteorological measurements. The objective of this study is to estimate the sensible heat flux over the built environment under convective conditions. Calculations were based on Monin-Obukhov similarity for temperature in the surface layer. The results illustrate a good agreement between the sensible heat flux inferred from the thermal roughness length approach and independent calibrated measurements from a scintillometer located inside the urban canopy. It also shows that using only one well-selected station can provide a good estimate of the sensible heat flux over the campus for convective conditions. Overall, this study illustrates how an extensive network of meteorological measurements can be a useful tool to estimate the sensible heat flux in complex urban environment

An investigation of ozone and planetary boundary layer dynamics over the complex topography of Grenoble combining measurements and modeling

International audienceThis paper concerns an evaluation of ozone (O3) and planetary boundary layer (PBL) dynamics over the complex topography of the Grenoble region through a combination of measurements and mesoscale model (METPHOMOD) predictions for three days, during July 1999. The measurements of O3 and PBL structure were obtained with a Differential Absorption Lidar (DIAL) system, situated 20 km south of Grenoble at Vif (310 m a.s.l.). The combined lidar observations and model calculations are in good agreement with atmospheric measurements obtained with an instrumented aircraft (METAIR). Ozone fluxes were calculated using lidar measurements of ozone vertical profiles concentrations and the horizontal wind speeds measured with a Radar Doppler wind profiler (DEGREANE). The ozone flux patterns indicate that the diurnal cycle of ozone production is controlled by local thermal winds. The convective PBL maximum height was some 2700 m above the land surface while the nighttime residual ozone layer was generally found between 1200 and 2200 m. Finally we evaluate the magnitude of the ozone processes at different altitudes in order to estimate the photochemical ozone production due to the primary pollutants emissions of Grenoble city and the regional network of automobile traffic

Estimation of urban sensible heat flux using a dense wireless network of observations

The determination of the sensible heat flux over urban terrain is challenging due to irregular surface geometry and surface types. To address this, in 2006–07, a major field campaign (LUCE) took place at the École Polytechnique Fédérale de Lausanne campus, a moderately occupied urban site. A distributed network of 92 wireless weather stations was combined with routine atmospheric profiling, offering high temporal and spatial resolution meteorological measurements. The objective of this study is to estimate the sensible heat flux over the built environment under convective conditions. Calculations were based on Monin–Obukhov similarity for temperature in the surface layer. The results illustrate a good agreement between the sensible heat flux inferred from the thermal roughness length approach and independent calibrated measurements from a scintillometer located inside the urban canopy. It also shows that using only one well-selected station can provide a good estimate of the sensible heat flux over the campus for convective conditions. Overall, this study illustrates how an extensive network of meteorological measurements can be a useful tool to estimate the sensible heat flux in complex urban environments

Etude d'un épisode photochimique à l'alde d'un modèle méso-échelle et de mesures intensives sur la région de Grenoble

La ville de Grenob le, située au carrefour de trois vallées, est systématiquement soumise à des périodes de smog estival avec de fortes concentrations en ozone (0 3), Au cours de l'été 1999, l'Association pour le contrôle et la préservation de l'air dans la région grenobloise (ASCOPARG) et l'École Polytechnique Fédérale de Lausanne (EPFL) ont mené conjointement -une campagne de mesures en déployant, durant un mois, un réseau de mesures au sol renforcé par des moyens de mesures à la vertical e. Deux périodes d'observations intensives (POl) ont eu lieu, la première fin juillet, et la deuxième dé but août. Les simulations ont été réa lisées pour la première POl (24-27 juill et) avec le modèle METeorological PHOtochem istry MODel (METPHOMOD) utilisant le mécanisme chimique Regional Atmospheric Chemistry Mechanism (RACM). Une technique de nesting one-way est utilisée avec une grande grille de 198 km de côté et une résolution de 6 x 6 km et une petite grille de 78 x 68 km avec une résolution de 2 x 2 km. À la verticale, 24 niveaux sont pris en compte jusqu'à 8 000 m. Au sol, les champs de vents, les concentrations d'03 et de dioxyde d'azote (NOx) sont bien reproduits par le modèle et mettent en évidence le déplacement horizontal du panache d'03 vers le sud avec un maximum d'03 de 95 ppb. Pour la verticale, les mesures et les simulations montrent une couche de mélange convective (CMC) supérieure à 2 000 rn, le transport horizontal du panache dans la CMC et la formation de la couche réservoir d'03' La CMC est donc plus haute en terrain de montagne qu'en plaine. Une stratification verticale spécifique de l'atmosphère, suivant trois couches, a été mise en évidence lors de cet épisode photoch imique sur Grenoble. Une simulation sans émissions sur le petit domaine de calcul a permis d'évaluer la production locale d'03de la ville à 32 ppb, soit un tiers de la concentration maximale mesurée et simulée dans le sud de l'agglomération

Influence of the interactions of local dynamical processes with large-scale flow on air quality in the grenoble area

The vertical distribution of ozone over the Grenoble area is investigated for two summer smog episodesin 1999 and 2003. The effects of the interactions of local dynamical processes with large-scale circulations wereestimated using numerical modelling. The results suggest that a terrain-induced shear layer above the boundary layerconfines pollutants within the valley. Vertical exchanges through this shear layer have a considerable influence on thenear-surface ozone concentration from day to day

A comparative study for the ability of different mesoscale models to forcast photochemical pollution events in the Grenoble area.

ISBN 3-902465-16-

An investigation of ozone and planetary boundary layer dynamics over the complex topography of Grenoble combining measurements and modeling

This paper concerns an evaluation of ozone (O-3) and planetary boundary layer (PBL) dynamics over the complex topography of the Grenoble region through a combination of measurements and mesoscale model (METPHOMOD) predictions for three days, during July 1999. The measurements of O-3 and PBL structure were obtained with a Differential Absorption Lidar ( DIAL) system, situated 20 km south of Grenoble at Vif (310m ASL). The combined lidar observations and model calculations are in good agreement with atmospheric measurements obtained with an instrumented aircraft (METAIR). Ozone fluxes were calculated using lidar measurements of ozone vertical profiles concentrations and the horizontal wind speeds measured with a Radar Doppler wind profiler (DEGREANE. The ozone flux patterns indicate that the diurnal cycle of ozone production is controlled by local thermal winds. The convective PBL maximum height was some 2700 m above the land surface while the nighttime residual ozone layer was generally found between 1200 and 2200 m. Finally we evaluate the magnitude of the ozone processes at different altitudes in order to estimate the photochemical ozone production due to the primary pollutants emissions of Grenoble city and the regional network of automobile traffic

031. Matthew 22:15-22

Matthew 22:15-22 is appointed for Proper 24, Series A. God is in control of church and state. The individual Christian relates to government, which is established by God, by obedience and service through vocation