L'accessibilité en transport: Méthodes et indicateurs

RÉSUMÉ De nos jours, les indicateurs, quel que soit le type, sont largement utilisés par les planificateurs urbains. Ceux-ci sont des outils clés permettant de décrire l’état des lieux, visualiser l’impact d’investissements et de politiques ou établir des cibles à différents horizons. Dans le domaine du transport, plusieurs indicateurs sont utilisés tels que part modale des différents modes, consommation d’essence, couverture des réseaux de transport, kilométrage parcouru, etc. Ce mémoire s’intéresse particulièrement aux indicateurs d’accessibilité. Une définition classique de l’accessibilité est la facilité avec laquelle on accède à une activité à partir d’un lieu donné et d’un mode (Dalvi et Martin 1976). Or, deux problématiques sont soulevées quant aux indicateurs d’accessibilité : l’ambiguïté entourant la définition de l’accessibilité et la difficulté de proposer des indicateurs d’accessibilité adéquats. Les indicateurs existants sont multiples. Or, peu ont la capacité d’évaluer la variabilité de l’offre de service en fonction de l’heure de la journée, du type de jour et de la localisation, ou encore d’évaluer la compétitivité entre les modes. De plus, les nouvelles technologies et données disponibles permettent de faciliter le calcul d’indicateurs. Ce mémoire propose donc d’abord une réflexion sur la typologie des indicateurs d’accessibilité. C’est-à-dire que ce mémoire propose une nouvelle classification des indicateurs sous quatre banches principales, les indicateurs individuels, universels, zonaux et ciblés. Cette typologie a également pour objectif d’orienter la proposition de méthodologie et d’indicateurs. Le mémoire poursuit avec la présentation de multiple méthodes, outils et indicateurs sensibles aux problématiques actuelles. La finalité est d'aider les planificateurs urbains à se doter d'indicateurs leur permettant d'évaluer l'accessibilité d'un lieu ou d'un territoire. Les indicateurs peuvent également servir à évaluer le gain potentiel d'accessibilité d’un projet ou à illustrer le gain suite à des modifications sur le réseau. Les indicateurs sont une représentation mathématique de l’accessibilité qui permet de quantifier le niveau d’accès d’un individu, d’un lieu, d’une zone ou d’un aménagement. Les indicateurs proposés sont basés sur diverses bases de données telles que les GTFS de la STM et les relevés GPS de Communauto, etc.----------ABSTRACT Indicators are largely used by urban planners. They help to describe current situations, to visualize future impacts of investments and politics, or to establish targets or standards for actual or future horizons. In the transport domain, different indicators are often used like mode share, gas consumption, public transit network coverage, etc. This research focuses on accessibility measures. Accessibility is a central concept when one wants to assess the efficiency of the linkages between home/activity locations and transportation services. Ensuring good accessibility to activity opportunities is part of current sustainability visions and this involves the capacity to measure how transportation services and networks support mobility needs at various locations and in different time periods. Since individuals have diverse mobility needs, it is important to evaluate the level of accessibility using time and space varying measures to take into account differentials in travel conditions and transit supply. This research offers some discussion over the various scales and types of accessibility measures as well as examples of measures estimated using scheduled-based transit supply. First, results of a measurement tool focusing on transit are presented. It was developed using visual interfaces from Google API and transit supply via GTFS (General transit feed specification) files made available by transit agencies. This tool allows to rapidly estimate the area that can be reached from a starting point within a specified travel time depending on time of departure and specific day of travel. Outputs can be visualized and used to estimate indicators (reachable area for instance). A second tool is also presented, this one allowing comparison of accessibility by car, walk and cycling using network-based paths. Again Google calculator is used to obtain times and distances to sets of destinations dispersed around the starting point and then to produce isochronic surfaces. Indicators and results are discussed

Comparison of long term tropospheric ozone trends measured by lidar and ECC ozonesondes from 1991 to 2010 in Southern France

International audienceECC (Electrochemical Concentration Cell) ozonesondes and UV DIAL (DIfferential Absorption Lidar) measurements have been carried out simultaneously at OHP (Observatoire de Haute Provence, 44°N, 6.7°E, 690 m) since 1991. A unique long-term trend assessment by two different instruments operated routinely at the same location is possible. Air mass trajectories have been calculated for all the ozone observations available at OHP. The bias between the seasonal mean calculated with lidar and ECC ozone vertical profiles for 4 time- periods of 5 years is 0.6 ppbv in the free troposphere (4-8 km). Larger differences (> 10 ppbv) are explained by the need for clear sky conditions during lidar observations. The measurements of both instruments have been combined to decrease the impact of short-term atmospheric variability on the trend estimate

Le patrimoine mondial de l'UNESCO sur la voie du Piémont pyrénéen vers Saint-Jacques-de-Compostelle : étude exploratoire des stratégies de relations publiques déployées en matière de développement durable

Le présent mémoire se penche sur l'étude des relations publiques entourant les sites du patrimoine mondial de l'UNESCO, avec pour objet la voie du Piémont pyrénéen du chemin Saint-Jacques-de-Compostelle en France. L'analyse a pour but de vérifier si les techniques de relations publiques déployées dans les stratégies de mise en valeur du patrimoine mondial sur la voie du Piémont pyrénéen contribuent au positionnement du patrimoine mondial comme agent de diffusion des principes de développement durable. Nous débuterons en situant la voie du Piémont pyrénéen dans la sphère internationale de l'UNESCO. Certains auteurs tiennent un discours élogieux à l'égard de cette voie jacquaire, soulignant sa richesse patrimoniale et l'effervescence entourant son urbanisation rapide, alors que d'autres décrient la forte augmentation du phénomène d'itinérance sur les chemins de Saint-Jacques-de-Compostelle, accentuant les effets négatifs d'une telle affluence. L'objectif de ce mémoire est de vérifier si les stratégies d'information, déployées sur la voie du Piémont pyrénéen, contribuent au respect et à l'application des principes de développement durable identifiés par le Centre du patrimoine mondial de l'UNESCO, favorisant ainsi l'émergence d'une entité vouée à la préservation du patrimoine matériel. Les techniques de collecte de données utilisées dans le cadre de cette recherche sont l'observation participante et l'entrevue semi-dirigée. Une méthode d'échantillonnage ciblé par critères est utilisée pour circonscrire les biens patrimoniaux représentatifs de la population, facilitant ainsi la mesure qualitative des approches de communication publique. Les biens patrimoniaux analysés sont différents à bien des égards. Ils nous permettent tout de même d'étudier les composantes communicationnelles entourant la voie du Piémont pyrénéen du chemin Saint-Jacques-de-Compostelle en France en ce qui a trait aux enjeux de développement durable. Le sceau UNESCO doit se porter garant de stratégies de communication efficaces consacrées au développement durable, non seulement pour les résidents mais également pour leur gouvernement. Dans ce contexte, il nous apparaît important de considérer la communication comme le quatrième pilier du développement durable, actualisant publiquement les trois autres (les sphères socio-sanitaire, économique et environnementale). \ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : relations publiques, patrimoine, développement durable, chemin Saint-Jacques-de-Compostelle en France, voie du Piémont pyrénée

Analysis of 20 years of tropospheric ozone vertical profiles by lidar and ECC at Observatoire de Haute Provence (OHP) at 44° N, 6.7° E

International audienceECC (Electrochemical Concentration Cell) ozonesondes and UV DIAL (DIfferential Absorption Lidar) lidar measurements have been carried out simultaneously at OHP (Observatoire de Haute Provence, 44° N, 6.7° E, 690 m) since 1991 and provide: (i) a good basis for long-term trend assessment by two different instruments at the same location and (ii) a 20-year climatology of tropospheric ozone in the Western Mediterranean basin. Air mass trajectories and mixing layer height (MLH) have been calculated for all the ozone observations available at OHP. The bias between the seasonal mean calculated with lidar and ECC ozone vertical profiles for 4 time-periods of 5 years is ∼0.6 ppbv in the free troposphere (4-8 km). Larger differences (≥10 ppbv) are explained by the need for clear sky conditions during lidar observations. Measurements of both instruments have been combined to decrease the impact of short-term atmospheric variability on the trend estimate. In the upper and the mid-troposphere, the spring maximum decreases by 5 ppbv during the 20-year period. In the mid-troposphere, the summer average decreases by 3 ppbv during the 20-year period. At altitude above 4 km, the variability of ozone attributed to different source regions can be in the range of 5-10 ppbv over 20 years and is mitigated by transport variability. In the lower troposphere and after year 2000, there is a sharp 5 ppbv decrease of the spring and summer averages of the surface measurements and of the ECC observations made in the 0.6-4 km altitude range. There is also a decrease of the lowermost troposphere ozone vertical gradient which is explained by the variability of the MLH (mixing layer height). The trends of ozone annual mean show significant decrease of 3 and 4 ppbv/decade from 1998 to 2010 at the surface and at the 2-4 km altitude range, while no significant trends are observed at higher altitude. Positive North Atlantic Oscillation (NAO) periods correspond to positive yearly mean ozone anomalies in the upper troposphere in relation with stratosphere-troposphere exchange. A negative NAO period in 2010 corresponds to an increase of the yearly mean ozone anomaly in the lower troposphere due to a more suitable transport of ozone precursors from Northern America and Western Europe

Tropospheric ozone long term trend observed by lidar and ECC ozonesondes at Observatoire de Haute Provence, Southern France

International audienceTropospheric ozone vertical profile measurements have been carried out at OHP (Observatoire de Haute Provence, 44°N, 6.7°E, 690 m) since 1991 using both UV DIAL (DIfferential Absorption Lidar) and ECC (Electrochemical Concentration Cell) ozonesondes. For the first time, ECC and lidar data measured at the same site, have been compared over a 24 year period. The comparison conducted reveals a bias between both measurement types (ECC - lidar) of the order of 0.6 ppbv. The measurements of both instruments have been however combined to decrease the impact of short-term atmospheric variability on the trend estimate. Air mass trajectories have been calculated for all the ozone observations available at OHP including ECMWF potential vorticity (PV) and humidity chnage along the trajectories. The interannual ozone variability shows a negligible trend in the mid troposphere, but a 0.36 ppbv/year significant positive ozone trend in the upper troposphere. The trends will be discussed using the variability of the meteorological parameters. Data clustering using PV and air mass trajectories is useful to identify the role of Stratosphere-Tropopshere Exchanges and long range transport of pollutants in the observed long term trends. In the lower troposphere, the interannual variability shows contrasted trends with an ozone decrease between 1998 and 2008, consistent with the NOx emission decrease, but a new period of ozone increase since 2008 which is not very well understood

Twenty years of tropospheric ozone variability measured in the western Mediterranean basin

Understanding of the tropospheric mid-latitude ozone trends in the free troposphere depends on several forcing mechanisms varying in different directions: change of continental emissions, Sratosphere-Troposphere Exchange (STE), upward ozone flux from the boundary layer (BL) and long range transport. The western Mediterranean is a well suited region to study the change of European emission but also the role of long range transport of other continental emissions (Ravetta et al., 2007). Moreover, Wilson et al., 2012, show a difference of ozone trend in south Europe compared to north and central Europe but south Europe is much less represented. In this work, the tropospheric ozone variability is derived from regular vertical profiles obtained using two types of instruments during the time period 1990-2010 at Observatoire de Haute Provence in Southern France (44N, 6E) which is included in the NDACC network: ECC balloon borne ozonesondes and a UV DIAL lidar. The latter provides data in the altitude range 3-14 km. A ground based UV photometer is also used since 1998. Seasonal variations in 2-km layers in the troposphere (2-8 km) for four five years periods were analysed with 3-days three dimensional backward trajectories calculated for each vertical profile during twenty years. Four source regions are identified: [Europe (lat>45N)], [Eastern Mediterranean], [Spain/Africa/North America (lat40N)]. Considering lidar and ozonesondes data seperatly we cannot identify a clear bias due to the measurement method while differences are related to the sampling conditions. Using lidar and ECC observation together, we have shown that there is a good correlation between ozone variability and changes of the transport pattern in the free troposphere, but no significant trends are observed above 3 km. In the lower troposphere, there is, however, a significant downward trend which is linked to the evolution of the planetary boundary layer height and changes in continental emissions. We will show also a joint analysis of ozone layers and the climatology of aerosol and water vapor layers. Water vapor profiles are obtained from the VAÏSALA sondes flown with the ECC sonde since 1990. The aerosol profiles are provided by the CALIPSO mission since 2006 using a trajectory approach to get a better matching between OHP observations and satellite data

Evolution of the stratospheric polar vortex in the Southern Hemisphere over the period 1979 - 2016

International audienceThe stratospheric polar vortex in the Southern Hemisphere plays an important role in the intensity of the stratospheric ozone destruction during austral spring, which started in the late 1970s. The so-called ozone hole has in turn influenced the evolution of weather patterns in the Southern Hemisphere in the last decades (WMO, 2018) The seasonal and interannual evolution of the Southern polar vortex has been analyzed using meteorological fields from the European Center for Meteorology Weather Forecasts ERA-Interim reanalyses and the MIMOSA model (Modélisation Isentrope du transport Méso-échelle de l'Ozone Stratosphérique par Advection, Hauchecorne et al., 2002). This model provides potential vorticity (PV) fields at several isentropic levels (475 K, 550 K and 675 K) that are used to evaluate the edge and intensity of the polar vortex as a function of time from 1979 to 2016. The edge of the vortex is computed on isentropic surfaces from the wind and gradient of PV as a function of equivalent latitude (e.g. Nash et al, 1996; Godin et al., 2001). In order to remove the noise of PV gradient determination, tracers have been incorporated into the model, tracking air masses inside and outside the vortex as a function of time. Results on the statistical analysis of the seasonal and interannual evolution of the intensity and extension of the southern polar vortex over the last 3 decades will be presented

Evolution of the intensity and duration of the Southern Hemisphere stratospheric polar vortex edge for the period 1979–2020

International audienceThe intensity and position of the Southern Hemisphere stratospheric polar vortex edge is evaluated as a function of equivalent latitude over the 1979-2020 period on three isentropic levels (475K, 550K and 675K) from ECMWF ERA-Interim reanalysis. The study also includes an analysis of the onset and breakup dates of the polar vortex, which are determined from wind thresholds (e.g. 15.2 m.s −1 , 20 m.s −1 and 25 m.s −1) along the vortex edge. The vortex edge is stronger in late winter, over September-October-November with the period of strongest intensity occurring later at the lowermost level. A lower variability of the edge position is observed during the same period. Long-term increase of the vortex edge intensity and breakup date is observed over the 1979-1999 period, linked to the increase of the ozone hole. Long-term decrease of the vortex onset date related to the 25 m.s −1 wind threshold is also observed at 475K during this period. The solar cycle and to a lower extent the quasi-biennal oscillation (QBO) and El Niño Southern Oscillation (ENSO) modulate the inter-annual evolution of the strength of the vortex edge and the vortex breakup dates. Stronger vortex edge and longer vortex duration is observed in solar minimum (minSC) years, with the QBO and ENSO further modulating the solar cycle influence, especially at 475K and 550K: during West QBO (wQBO) phases, the difference between vortex edge intensity for minSC and maxSC years is smaller than during East QBO (eQBO) phases. The polar vortex edge is stronger and lasts longer for maxSC/wQBO years than for maxSC/eQBO years. ENSO has a weaker impact but the vortex edge is somewhat stronger during cold ENSO phases for both minSC and maxSC years

Evolution of the stratospheric polar vortex in the Southern and Northern Hemispheres over the period 1979-2020

International audienceThe stratospheric polar vortex in the Southern Hemisphere plays an important role in the intensity of the stratospheric ozone destruction during austral spring, which started in the late 1970s. The so-called ozone hole has in turn influenced the evolution of weather patterns in the Southern Hemisphere in the last decades (WMO, 2018). The Northern Hemisphere polar vortex is less stable because of larger dynamical activity in winter. It is thus less cold and polar arctic ozone losses are less important. The seasonal and interannual evolution of the polar vortex in both hemispheres has been analyzed using meteorological fields from the European Center for Meteorology Weather Forecasts ERA-Interim reanalyses and the MIMOSA model (Modélisation Isentrope du transport Méso-échelle de l’Ozone Stratosphérique par Advection, Hauchecorne et al., 2002). This model provides high spatial resolution potential vorticity (PV) and equivalent latitude fields at several isentropic levels (675K, 550K and 475K) that are used to evaluate the temporal evolution of the polar vortex edge. The edge of the vortex is computed on isentropic surfaces from the wind and gradient of PV as a function of equivalent latitude (e.g. Nash et al, 1996; Godin et al., 2001). On an interannual scale, the signature of some typical forcings driving stratospheric natural variability such as the 11-year solar cycle, the quasi-biennial oscillation (QBO), and El Niño Southern Oscillation (ENSO) is evaluated. The study includes analysis of the onset and breakup dates of the polar vortex, which are determined from the wind field along the vortex edge. Several threshold values, such as 15.2m/s, 20m/s and 25m/s following Akiyoshi et al. (2009) are used. Results on the seasonal and interannual evolution of the intensity and position of the vortex edge, as well as the onset and breakup dates of the Southern and Northern polar vortex edge over the 1979 – 2020 period will be show

Features relevance analysis for emotion classification with physiological sensors

International audienceWith the development of wearable physiological sensors, emotion estimation becomes a hot topic in the literature. Databases of physiological signals recorded during emotional stimulation are acquired and machine learning algorithms are used. Yet, which are the most relevant signals to detect emotions is still a question to be answered. In order to better understand the contribution of each signal, and thus sensor, to the emotion estimation problem, several feature selection algorithms were implemented on two databases freely available to the research community (DEAP and MANHOB-HCI). Both databases manipulate emotions by showing participants short videos (video clips or part of movies respectively). Features extracted from Galvanic Skin response were found to be relevant for arousal estimation in both databases. Other relevant features were eye closing rate for arousal, variance of zygomatic EMG for valence (those features being only available for DEAP). The hearth rate variability pow er in three frequency bands also appeared to be very relevant, but only for MANHOB-HCI database where heat rate was measured using ECG (whereas DEAP used PPG). This suggests that PPG is not accurate enough to estimate HRV precisely. Finally we showed on DEAP database that emotion classifiers need just a few well selected features to obtain similar performances to literature classifiers using more features