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L’ évitement scolaire : un effet « boomerang » de la labélisation en politique de la ville ?
No full textNotes IPP n°110En France, la politique de la ville cible les quartiers urbains confrontés à de très grandes difficultés sociales et économiques, d’abord qualifiés de « zones urbaines sensibles » puis, depuis 2014, de « quartiers prioritaires ». Ces quartiers bénéficient de subventions publiques visant à réduire la ségrégation urbaine et à améliorer les conditions de vie des habitants (logement, services publics, sécurité) et leurs opportunités socio-économiques (éducation, emploi). De nombreux travaux de recherche ont mis en balance les bénéfices et les effets potentiellement contre-productifs des politiques publiques menées dans ces quartiers. Cette note étudie un revers de la politique de la ville encore peu documenté : la stigmatisation territoriale, qui est analysée ici sous le prisme de l’évitement scolaire des collèges publics situés dans les quartiers périmétrés par la politique.L’étude prend appui sur une réforme de la géographie prioritaire intervenue en 2014, qui a redessiné la carte des quartiers ciblés à l’aide d’un carroyage très fin du territoire et d’un seuil d’éligibilité fondé sur le revenu fiscal médian des résidents de chaque carreau. Sans que la carte scolaire ait été modifiée par la réforme, certains collèges sont ainsi « entrés » dans le périmètre de la politique, et d’autres en sont « sortis ». La comparaison des collèges des quartiers situés juste au-dessus et au-dessous du seuil d’éligibilité, avant et après la réforme, permet d’évaluer l’impact causal moyen de la labélisation du quartier en politique de la ville sur l’évitement scolaire
Can Firm Subsidies Spread Growth?
No full textHow do firms diffuse resources and do they spillover outside headquarter intensive areas? We show R&D subsidies induce French firms to hire new workers, often in new establishments and commuting zones. Using subsidy induced labor demand shocks and past employment patterns, we estimate a within industry spillover elasticity of .26 to non-subsidy firms, rising to .35 for openings outside of headquarter areas. Spillovers are also significant across firm branches and for firms. While subsidies are nominally awarded to headquarters, firms expand to distribute spillovers more broadly
A tale of Work from Home in the aftermath of the Great Recession: Learning from high-frequency diaries
No full textInternational audienceThis study contributes to the growing literature on Work from Home (WfH), focusing on the responsiveness of the phenomenon to the business cycle. In particular, the Great Recession led many states to implement unprecedented and expansionary unemployment benefit measures (Extended Benefit, EB), which were often revoked when the recession resumed. EB measures differ widely in generosity and timing across states. We exploit this, for identification purposes, by linking the interview date of the respondents to the American Time Use Survey (ATUS) to the dates of implementation of EB programs, in the respondent’s state of residence. ATUS provides unique cross-sectional information on WfH for a representative sample of Americans. Taking an approach inspired by a Regression Discontinuity Design, we find that recessions, as proxied by EB expansionary measures, significantly increase women’s commuting. In contrast, women’s remote work increases with economic recovery, as captured by EB contractionary measures. The evidence for men is less clear-cut
HydroModPy: A Python toolkit to automate the deployment of groundwater models with subsurface-surface interactions on multiple sites
No full textInternational audienceThe need for predictive models increases as the pressure of global change intensifies. Regional-scale modeling of shallow unconfined aquifers (10-100 m depth) remains challenging, especially in complex basement aquifers. Controlled both by topography and geology, groundwater flows are organized from hillslope to catchment scale. It is particularly the case in crystalline regions with low aquifer volumes and wet climates, resulting in significant subsurface-surface interactions with very few information available to constrain models. To address this, we present HydroModPy, an application developed in Python as a toolbox for automatic deployment of groundwater flow models. HydroModPy integrates geospatial processing (WhiteBoxTools) with groundwater flow and transport simulation tools (MODFLOW and MODPATH via FloPy). It is designed to call other groundwater flow solvers, facilitate multi-site deployment, integrate pre- and post-processing functions such as catchment extraction from a DEM and an advanced representation of head and flow results. Emphasis is placed on integrating aquifer geometry complexities and hydraulic properties heterogeneity (compartmentalization, exponential decay, implementation of a 3D geological model, etc.). HydroModPy's user-friendly Python interface allows for testing and exploring various aquifer models across different geomorphological contexts and recharge conditions. Ongoing improvements include methods for calibrating and estimating hydraulic properties using multiple datasets such as hydrographic network maps, streamflow, and piezometric level data. HydroModPy is developed as an open-source toolkit. It is currently being used in climate change effects on groundwater-dependent ecosystems and water resource management issues. Collaborative development should enhance the modeling capacity of near-surface aquifers, facilitate their extension to the regional scale for predictive purposes
Évaluation de l'impact des rejets d'eaux pluviales urbaines (RUTP) sur les eaux de surface franciliennes par HRMS non ciblée et modélisation écotoxicologique
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The CHIMERE chemistry-transport model v2023r1
No full textInternational audienceA new version of the CHIMERE model is presented. This version contains both computational and physico-chemical changes. The computational changes make it easy to choose the variables to be extracted as a result, including values of maximum sub-hourly concentrations. Performance tests show that the model is 1.5 to 2 times faster than the previous version for the same setup. Processes such as turbulence, transport schemes and dry deposition have been modified and updated. Optimization was also performed for the management of emissions such as anthropogenic and mineral dust. The impact of fires on wind speed, soil properties and leaf area index (LAI) was added. Pollen emissions, transport and deposition were added for birch, ragweed, olive and grass. The model is validated with a simulation covering Europe with a 60 km × 60 km resolution and the entire year of 2019. Results are compared to various measurements, and statistical scores show that the model provides better results than the previous versions
Investigating Thermal Contrasts Between Jupiter's Belts, Zones, and Polar Vortices With VLT/VISIR
No full textInternational audienceUsing images at multiple mid-infrared wavelengths, acquired in 2018 May using the Very Large Telescope Imager and Spectrometer (VISIR) instrument on ESO's Very Large Telescope (VLT), we study Jupiter's pole-to-pole thermal, chemical and aerosol structure in the troposphere and stratosphere. We confirm that the pattern of cool and cloudy anticyclonic zones and warm cloud-free cyclonic belts persists throughout the mid-latitudes, up to the polar boundaries, and evidence a strong correlation with the vertical maximum windshear and the locations of Jupiter's zonal jets. At high latitudes, VISIR images reveal a large region of mid-infrared cooling poleward ∼64°N and ∼67°S extending from the upper troposphere to the stratosphere, co-located with the reflective aerosols observed by JunoCam, and suggesting that aerosols play a key role in the radiative cooling at the poles. Comparison of zonal-mean thermal properties and high-resolution visible imaging from Juno allows us to study the variability of atmospheric properties as a function of altitude and jet boundaries, particularly in the cold southern polar vortex. However, the southern stratospheric polar vortex is partly masked by a warm mid-infrared signature of the aurora. Co-located with the southern main auroral oval, this warming results from the auroral precipitation and/or joule heating which heat the atmosphere and thus cause a significant stratospheric emission. This high emission results from a large enhancement of both ethane and acetylene in the polar region, reinforcing the evidence of enhanced ion-related chemistry in Jupiter's auroral regions
Ancient volcanism may have influenced patterns of hydrated regolith on Mars
No full textInternational audienceThe hydration of the martian regolith at decimeter depth scales varies regionally, suggestive of geologically sustained processes, independent of diurnal soil-atmosphere exchange. A combination of factors, including residual hydration from ancient processes in the hydrosphere/cryosphere, seasonal exchange between the crust and atmosphere in the martian critical zone, or structural water in minerals or salts sourced via hydrothermal processes can contribute to such lateral changes in bulk regolith hydration. Here, we consider the theoretical extent of regolith hydration from explosive volcanic eruptions and subsequent hydration. While magmatic degassing has previously been considered as a contributing factor to regolith hydration, the relationship between hydrated regolith and the depositional footprint of volcanic eruption columns and associated atmospheric dispersal remains poorly known. We run simulations of eruptions in an ancient atmosphere over a martian year to account for seasonality and produce theoretical ash deposition maps which are then input into a geographic weighted regression model to predict hydrated regolith. We find that ash deposited via explosive volcanism can help explain certain patterns of hydration enrichment in the martian regolith, including those near Apollinaris Patera Arabia Terra, and Sabea Terra. While the global patterns of regolith hydration cannot be explained by one process alone, we found that hydrated ash likely contributed to hydrated regolith at a commensurable level to other leading hydration mechanisms. Plain language summary. The surface of Mars is blanketed by a pervasive layer of regolith, a mixture of unconsolidated sediment of multiple grainsizes that range from very fine dust to larger pebbles. This regolith contains significant amounts of water that are stored in the chemical bonds that make up the individual regolith grains. The amount of water bound in the regolith is spatially inconsistent throughout the planet; some areas contain more water, while others contain less. Several different geologic processes have likely contributed to these inconsistencies, including volcanic processes. While gentle volcanic outgassing has already been considered, here we specifically looked at how explosive volcanism and the associated spreading of volcanic ash in the martian atmosphere may have contributed to hydrated regolith patterns. By using multiple numerical simulations, we found that explosive volcanism likely contributed to certain patterns of hydration in the regolith along with other geologic processes
Gravity Wave Momentum Fluxes Estimated From Project Loon Balloon Data
No full textInternational audienceWe present estimates of gravity wave momentum fluxes calculated from Project Loon superpressure balloon data collected between 2013 and 2021. In total, we analyzed more than 5,000 days of data from balloon flights in the lower stratosphere, flights often over regions or during times of the year without any previous in-situ observations of gravity waves. Maps of mean momentum fluxes show significant regional variability; we analyze that variability using the statistics of the momentum flux probability distributions for six regions: the Southern Ocean, the Indian Ocean, and the tropical and extratropical Pacific and Atlantic Oceans. The probability distributions are all approximately log-normal, and using their geometric means and geometric standard deviations we statistically explain the sign and magnitude of regional mean and 99th percentile zonal momentum fluxes and regional momentum flux intermittencies. We study the dependence of the zonal momentum flux on the background zonal wind and argue that the increase of the momentum flux with the wind speed over the Southern Ocean is likely due to a varying combination of both wave sources and filtering. Finally, we show that as the magnitude of the momentum flux increases, the fractional contributions by high-frequency waves increases, waves which need to be parameterized in large-scale models of the atmosphere. In particular, the near-universality of the log-normal momentum flux probability distribution, and the relation of its statistical moments to the mean momentum flux and intermittency, offer useful checks when evaluating parameterized or resolved gravity waves in models
Improved subseasonal prediction of South Asian monsoon rainfall using data-driven forecasts of oscillatory modes
No full textInternational audienceThe South Asian monsoon affects more than a billion people in the Indian subcontinent. The monsoon intraseasonal oscillation (MISO) determines the spatial structure of the monsoon rainfall on subseasonal timescales, and its accurate prediction is therefore key for agricultural and hydrological planning. Here, we combine data-driven forecasts of MISO with an ensemble of dynamical forecasts of the full system, leveraging the predictability of MISO to improve monsoon forecasts. Our results show significant improvement compared to state-of-the-art dynamical model forecasts, demonstrating the potential of data-driven forecasts to improve subseasonal monsoon prediction