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Pico-Light H2O: Intercomparison Of In Situ Water Vapour Measurements During The Asa 2022 Campaign
No full textInternational audienceThe mid-infrared lightweight tunable diode laser hygrometer, "Pico-Light H2O", the successor to Pico-SDLA H2O, is presented and its performances are evaluated during the AsA 2022 balloon-borne intercomparison campaign conducted at the CNES Aire-sur-l'Adour (AsA, 43.70° N; 0.25° W) balloon launch facility and the Aeroclub d'Aire-sur-l'Adour in France. The Pico-Light instrument has primarily been developed for sounding of the upper troposphere and stratosphere, although during the AsA 2022 campaign we expand the range of comparison to include additionally the lower troposphere. Three different types of hygrometer and two models of radiosonde were flown, operated by the French Space Agency (CNES) and the NOAA Global Monitoring Laboratory (GML) scientific teams: Pico-Light H2O, the NOAA Frost Point Hygrometer (FPH), the micro-hygrometer (in an early phase of development), and M20 and iMet-4 sondes. Within this framework, we intend to validate measurements of Pico-Light H2O through a first intercomparison with the NOAA FPH instrument. The in situ monitoring of water vapour in the upper troposphere-lower stratosphere continues to be very challenging from an instrumental point of view because of the very small amounts of water vapour to be measured in these regions of the atmosphere. Between the lapse rate tropopause (11-12.3 km) and 20 km, the mean relative difference between water vapour mixing ratio measurements by Pico-Light H2O and NOAA FPH was 4.2 % ± 7.7 %, and the mean tropospheric difference was 3.84 % ± 23.64 %, with differences depending on the altitude range considered. In the troposphere, relative humidity (RH) over water comparisons led to agreement between Pico-Light and NOAA FPH of -0.2 % on average, with excursions of about 30 % RH due to moisture variability. Expanding the comparison to meteorological sondes, the iMet-4 sondes agree well with both Pico-Light and FPH between the ground and 7.5 km (within ± 3 % RH), as do the M20 sondes, up to 13 km, which are wet-biased by 3 % RH and dry-biased by 20 % in cases of saturation
Trace element partitioning in the lunar magma ocean: an experimental study
No full textInternational audienceModeling the behavior of trace elements during lunar magma ocean solidification is important to further our understanding of the chemical evolution of the Moon. Lunar magma ocean evolution models rely on consistent datasets on how trace elements partition between a lunar silicate melt and coexisting minerals at different pressures, temperatures, and redox conditions. Here we report new experimental trace element partition coefficients (D) between clinopyroxene (cpx), pigeonite, orthopyroxene, plagioclase, olivine (ol), and silicate melt at conditions relevant for the lunar magma ocean. The data include Dcpx-melt at ambient and high pressures (1.5 GPa and 1310 °C), and partition coefficients at ambient pressure for pig, opx, ol, and pl. Overall, clinopyroxene is a phase that may control the fractionation of key geochemical trace element ratios, such as Lu/Hf and Sm/Nd, during the evolution of the lunar magma ocean. We explore the impact of the new silicate Dmineral-melt on the trace element evolution of the lunar magma ocean and we find that accessory phosphate minerals, such as apatite or whitlockite are of critical importance to explain the observed trace element and isotopic signature of the KREEP reservoir on the Moon. The new partition coefficients were applied to calculate the trace element evolution of the residual melts of the crystallizing lunar magma ocean and we propose a new trace element composition for the urKREEP reservoir. The new data will be useful for future thermo-chemical models in order to adequately predict the duration of the lunar magma ocean and the age of the Moon
On The Formation Of Biogenic Secondary Organic Aerosol In Chemical Transport Models: An Evaluation Of The Wrf-Chimere (V2020R2) Model With A Focus Over The Finnish Boreal Forest
No full textInternational audienceWe present an evaluation of the regional chemical transport model (CTM) WRF-CHIMERE (v2020r2) for the formation of biogenic secondary organic aerosol (BSOA) with a focus over the Finnish boreal forest. Formation processes of biogenic aerosols are still affected by different sources of uncertainties, and model predictions vary greatly depending on the levels of details of the adopted chemical and emissions schemes. In this study, air quality simulations were conducted for the summer of 2019 using different organic aerosol (OA) schemes (as currently available in the literature) to treat the formation of BSOA. First, we performed a set of simulations in the framework of the volatility basis set (VBS) scheme carrying different assumptions for the treatment of the aging processes of BSOA. The results of the model were compared against high-resolution (i.e., 1 h) organic aerosol mass and size distribution measurements performed at the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR-II) site located in Hyytiälä, in addition to other gas-phase species such as ozone (O3), nitrogen oxides (NOx), and biogenic volatile organic compound (BVOC) measurements of isoprene (C5H10) and monoterpenes. We show that WRF-CHIMERE could reproduce well the diurnal variation of the measured OA concentrations for all the investigated scenarios (along with the standard meteorological parameters) as well as the increase in concentrations during specific heat wave episodes. However, the modeled OA concentrations varied greatly between the schemes used to describe the aging processes of BSOA, as also confirmed by an additional evaluation using organic carbon (OC) measurement data retrieved from the EBAS European databases. Comparisons with isoprene and monoterpene air concentrations revealed that the model captured the observed monoterpene concentrations, but isoprene was largely overestimated, a feature that was mainly attributed to the overstated biogenic emissions of isoprene. We investigated the potential consequences of such an overestimation by inhibiting isoprene emissions from the modeling system. Results indicated that the modeled BSOA concentrations increased in the northern regions of the domain (e.g., Finland) compared to southern European countries, possibly due to a shift in the reactions of monoterpene compounds against available radicals, as further suggested by the reduction in α-pinene modeled air concentrations. Finally, we briefly analyze the differences in the modeled cloud liquid water content (clwc) among the simulations carrying different chemical schemes for the treatment of the aging processes of BSOA. The results of the model indicated an increase in clwc values at the SMEAR-II site, for simulations with higher biogenic organic aerosol loads, most likely as a result of the increased number of biogenic aerosol particles capable of activating cloud droplets
Informal sector, remittances, and political stability: A study of Granger-causality in four large geopolitical sets
No full textThis paper investigates the relationships between remittances, the informal sector, and political stability across various large geopolitical sets, including the Middle East and North Africa (MENA), Sub-Saharan Africa, Latin America, and the Organisation for Economic Cooperation and Development (OECD) countries. Employing Granger causality tests to determine the predominate direction of causality and panel vector autoregressive models, we explore the dynamics of these relationships over short, medium, and long-term periods.Our findings reveal a significant short-term impact of remittances on the growth of the informal sector in the MENA, Sub-Saharan Africa, and Latin America, suggesting that remittances directly influence economic activities within this sector, likely due to their use in undeclared activities and the funding of informal local businesses. However, the influence of remittances wanes over time, indicating their primary role in addressing immediate economic needs rather than fostering long-term sector growth. Political stability shows minimal direct causal interaction with the informal sector, hinting at the sector's role as an adaptive mechanism in politically volatile regions.In OECD countries, remittances maintain a persistent influence on the informal sector over longer periods, reflecting their role in more strategic economic decisions. Additionally, our study explores the complex dynamics in countries with high remittance-to-GDP ratios, identifying a strong predictive power of the informal sector size on remittance flows, which points to the sector's pivotal economic role. We have extended our analysis to OECD countries, using outward remittances as a proxy for inward migration. We found that the size of the informal sector can predict outward remittance flows and political stability, highlighting the crucial role of the informal economy in migration and political dynamics.The results underscore the need for region-specific policy interventions and highlight the importance of understanding the temporal dynamics of remittances. This study contributes to the discourse on economic development strategies, suggesting that leveraging remittances effectively requires comprehensive policy approaches that consider their varied impacts across different regional and economic contexts.Cet article explore les liens entre les envois de fonds, le secteur informel et la stabilité politique dans plusieurs ensembles géopolitiques majeurs, dont le Moyen-Orient et l'Afrique du Nord (MENA), l'Afrique subsaharienne, l'Amérique latine et les pays de l'Organisation de Coopération et de Développement Économiques (OCDE). En utilisant des tests de causalité de Granger pour déterminer la direction prédominante de la causalité et des modèles autorégressifs vectoriels de panel, nous examinons la dynamique de ces relations sur des périodes courtes, moyennes et longues.Nos résultats révèlent un impact significatif à court terme des envois de fonds sur la croissance du secteur informel dans la région MENA, l'Afrique subsaharienne et l'Amérique latine, suggérant que les envois de fonds influencent directement les activités économiques au sein de ce secteur, probablement en raison de leur utilisation dans des activités non déclarées et le financement d'entreprises locales informelles. Cependant, l'influence des envois de fonds diminue avec le temps, indiquant leur rôle principal dans la réponse aux besoins économiques immédiats plutôt que dans la promotion de la croissance à long terme du secteur. La stabilité politique montre une interaction causale directe minimale avec le secteur informel, suggérant le rôle du secteur comme mécanisme d'adaptation dans les régions politiquement instables.Dans les pays de l'OCDE, les envois de fonds maintiennent une influence persistante sur le secteur informel sur de plus longues périodes, reflétant leur rôle dans des décisions économiques plus stratégiques. De plus, notre étude explore la dynamique complexe dans les pays ayant des ratios envois de fonds/PIB élevés, identifiant un fort pouvoir prédictif de la taille du secteur informel sur les flux de transferts de fonds, ce qui souligne le rôle économique central du secteur. Nous avons étendu notre analyse aux pays de l'OCDE, en utilisant les envois de fonds sortants comme indicateur de la migration entrante. Nous avons constaté que la taille du secteur informel peut prédire les flux de fonds sortants et la stabilité politique, soulignant le rôle crucial de l'économie informelle dans la dynamique migratoire et politique.Les résultats soulignent la nécessité d'interventions politiques spécifiques à chaque région et l'importance de comprendre la dynamique temporelle des envois de fonds. Cette étude contribue au discours sur les stratégies de développement économique, suggérant qu'une utilisation efficace des envois de fonds nécessite des approches politiques globales qui prennent en compte leurs impacts variés selon les contextes régionaux et économiques
Emerging multiscale insights on microbial carbon use efficiency in the land carbon cycle
No full textInternational audienceMicrobial carbon use efficiency (CUE) affects the fate and storage of carbon in terrestrial ecosystems, but its global importance remains uncertain. Accurately modeling and predicting CUE on a global scale is challenging due to inconsistencies in measurement techniques and the complex interactions of climatic, edaphic, and biological factors across scales. The link between microbial CUE and soil organic carbon relies on the stabilization of microbial necromass within soil aggregates or its association with minerals, necessitating an integration of microbial and stabilization processes in modeling approaches. In this perspective, we propose a comprehensive framework that integrates diverse data sources, ranging from genomic information to traditional soil carbon assessments, to refine carbon cycle models by incorporating variations in CUE, thereby enhancing our understanding of the microbial contribution to carbon cycling.Earth System Models (ESMs) are indispensable tools for predicting the planetary response to climate change 1 . The accuracy and reliability of ESMs are crucial for informing climate projections that guide policy decisions. Soils store more carbon (C) than plants, the surface ocean or the atmosphere, and thus are critical for the functioning of the Earth system 2 . While ESMs are becoming increasingly complex, their predictions of soil organic C (SOC) stocks have improved only marginally in recent decades 3,4
Résilience d’une destination touristique à l’ère post-Covid : le cas de Val d’Europe Agglomération
No full textInternational audienceL’objet de ce chapitre est de comprendre le changement de cap que VEA a entreprisen ce qui concerne son attractivité. Nous allons analyser les mécanismes en jeu, notammentl’attraction de nouvelles entreprises ne relevant pas du secteur touristique ainsique de nouvelles populations cibles. Ces mécanismes relèvent-ils de la résilience desterritoires urbains ? Au-delà de la crise sanitaire, sont-ils en mesure de préparer le territoireà répondre aux impératifs de l’urgence climatique et au-delà de la transformationécologique ?Afin de répondre à ces questions, nous commencerons par établir un cadre théoriquepour notre analyse en nous appuyant sur le concept de résilience adaptative (Fabryet Zeghni 2019, 2020a, 2020b). Dans un deuxième point, nous présenterons les résultatsde notre exploration
Mixing Douglas' and weak majorization and factorization theorems
No full textThe Douglas' majorization and factorization theorem characterizes the inclusion of operator ranges in Hilbert spaces. Notably, it reinforces the well-established connections between the inclusion of kernels of operators in Hilbert spaces and the (inverse) inclusion of the closures of the ranges of their adjoints. This note aims to present a "mixed" version of these concepts for operators with a codomain in a product space. Additionally, an application in control theory of coupled systems of linear partial differential equations is presented
How (absent) fans influenced football during the COVID-19 pandemic?
No full textThe fact that home football teams win more games than away teams has been largely discussed in the literature. Crowd factors appear to be the most dominant cause of this home advantage. At the end of the 2019-2020 season, the Covid-19 pandemic forced European football teams to close their stadium to fans, allowing researchers to exploit this natural experiment to analyze the effects of crowd on match outcomes and referees' decisions.To answer to this question, we used match data played in the top two divisions of four of the main national professional leagues in European countries and Portugal in the 2018-19 and the 2019-20 seasons. We find that the total absence of a generally supportive crowd has a significant effect on home advantage. This results in a reduction of the chances of a home win, a poorer performance by the home team's players, and more severe refereeing decisions towards the home team and less severe towards the away team.</p
Independent media, propaganda, and religiosity: Evidence from Poland
No full textInternational audienceExploring a drastic change in media landscape in Poland, we show that mainstream media can significantly affect religious participation. After nationalist populist party PiS came to power in 2015, news on state and private independent TV diverged due to propaganda on state TV, resulting in a switch of some of its audience to independent TV. Municipalities with access to independent TV continued to follow a long-term secularization trend, while municipalities with access only to state TV experienced a reversal of this trend. An online experiment sheds light on the mechanisms underlying the effect of exposure to independent news on religiosity