L’apport de la simulation multi-agent du trafic routier pour l’estimation des pollutions atmosphériques automobiles

National audienceLa pollution atmosphérique est aujourd’hui considérée comme cancérigène pour la santé humaine (OMS, 2013). Avec le bruit, elle est l’une des premières nuisances directement ressenties par les populations en milieu urbain. Son évaluation présente un véritable enjeu pour les pouvoirs publics afin de mieux en identifier ses sources, ses impacts en vue de définir des politiques territoriales (PDU, cadastre d’émission). A l’échelle locale, la pollution atmosphérique est à relier directement à l’intensité des sources d’émissions qui vont accentuer, ou non, la qualité de l’air extérieure (Elichegaray, 2010) . En milieu urbain, le premier contributeur en émission de NOx, CO, ou PM10 dans l’atmosphère est le trafic routier (CITEPA, 2014)

In-water reflectance spectra measured on-board a jet-ski across a complex nearshore zone of case-2 waters during the ECORS experiment

International audienceIn situ reflectance spectra have been measured during the international field experiment ECORS-Truc Vert 2008 (SW France) in the nearshore zone over a complex bathymetry and in moderately turbid waters (SPM 7 m). The jet-ski provides a valuable mean to gather optical data in shallow waters and in environments hard to sample with traditional coastal ships. Main results show reflectance spectra are typical of the presence of mineral particles with light absorption at short wavelengths. The shape and magnitude of the spectra are also very representative of the type of waters and bottom depth : the maximum of reflectance is reached around 500 nm in low turbidity waters (SPM<1 mg/l) while moving to the yellow spectral band (570-580 nm) in moderately turbid shallow waters (SPM=4 mg/l) where rip currents drive sediments outside the surf zone. A very original dataset has been obtained considering the synchronization of optical data, bathymetric surveys and Formosat-2 high resolution satellite image all collected the same day (5 April 2008). In the present study, this dataset is tested to inverse optical models for bathymetry retrieval in order to compute diachronic bathymetric maps as the coastline is changing very fast and need frequent updates of the bathymetry

Interannual memory effects for spring NDVI in semi-arid South Africa

Almost 20 years of Normalized Difference Vegetative Index (NDVI) and precipitation (PPT) data are analysed to better understand the interannual memory effects on vegetation dynamics observed at regional scales in Southern Africa (SA). The study focuses on a semi-arid region (25°S–31°S; 21°E–26°E) during the austral early summer (September–December). The memory effects are examined using simple statistical approaches (linear correlations and regressions) which require the definition of an early summer vegetation predictand (December NDVI minus September NDVI) and a consistent set of potential predictors (rainfall amount, number of rainy days, rainfall intensity, NDVI and Rain-Use-Efficiency) considered with 4 to 15-month time-lag. An analysis over six SA sub-regions, corresponding to the six major land-cover types of the area reveals two distinct memory effects. A “negative” memory effect (with both rainfall and vegetation) is detected at 7 to 10-month time-lag while a “positive” memory effect (with vegetation only) is observed at 12 to 14-month time-lag. These results suggest that interannual memory effects in early summer vegetation dynamics of semi-arid South Africa may preferably be driven by biological rather than hydrological mechanisms

Assessments for the impact of mineral dust on the meningitis incidence in West Africa.

9 pagesInternational audienceRecently, mineral dust has been suspected to be one of the important environmental risk factor for meningitis epidemics in West Africa. The current study is one of the first which relies on long-term robust aerosol measurements in the Sahel region to investigate the possible impact of mineral dust on meningitis cases (incidence). Sunphotometer measurements, which allow to derive aerosol and humidity parameters, i.e., aerosol optical thickness, Angström coefficient, and precipitable water, are combined with quantitative epidemiological data in Niger and Mali over the 2004-2009 AMMA (African Monsoon Multidisciplinary Analysis) program period. We analyse how the extremely high aerosol loads in this region may influence both the calendar (onset, peaks, end) and the intensity of meningitis. We highlight three distinct periods: (i) from November to December, beginning of the dry season, humidity is weak, there is no dust and no meningitis cases; (ii) from January to April, humidity is still weak, but high dust loads occur in the atmosphere and this is the meningitis season; (iii) from May to October, humidity is high and there is no meningitis anymore, in presence of dust or not, which flow anyway in higher altitudes. More specifically, the onset of the meningitis season is tightly related to mineral dust flowing close to the surface at the very beginning of the year. During the dry, and the most dusty season period, from February to April, each meningitis peak is preceded by a dust peak, with a 0-2 week lead-time. The importance (duration, intensity) of these meningitis peaks seems to be related to that of dust, suggesting that a cumulative effect in dust events may be important for the meningitis incidence. This is not the case for humidity, confirming the special contribution of dust at this period of the year. The end of the meningitis season, in May, coincides with a change in humidity conditions related to the West African Monsoon. These results, which are interpreted in the context of recent independent epidemiological studies on meningitis highlight, (i) the particular role of dust during the dry season (low humidity conditions) on the onset and the intra-seasonal variability of the meningitis season; (ii) the specific role of high humidity at the end of the meningitis season in two Sahelian countries particularly affected by the disease

"About the potential role of dust aerosols on the meningitis disease in Western Africa”

International audienc

Validation des corrections atmosphériques ( application au capteur SeaWIFS en milieu côtier)

BOULOGNE-BU Droit Lettres (621602101) / SudocSudocFranceF

De Mustard à Qaémléo : la construction d’un observatoire environnemental participatif

International audienceDepuis 2017, Dijon Métropole développe un projet de ville intelligente pour améliorer la gestion urbaine au quotidien. Ce nouveau récit métropolitain s’inscrit également dans une approche originale pour garantir un accès sécurisé aux données produites par la ville intelligente. Parallèlement à cette action, les chercheurs du campus dijonnais se sont engagés, dans le cadre du programme POPSU, à constituer un observatoire intelligent pour la qualité environnementale selon les principes FAIR : Facile à trouver, Accessible, Interopérable, Réutilisable. Se pose alors la question de comment faire converger ces infrastructures smart pour FAIR.E métropole

Variabilité et prévisibilité de l'état de la végétation (appréhendé par télédétection) en Afrique de l'Ouest

International audienc