119 research outputs found
Chapter 2. Climate change in the Mediterranean region
La rĂ©gion mĂ©diterranĂ©enne est reconnue comme Ă©tant une des rĂ©gions au monde particuliĂšrement sensible au changement climatique. Plusieurs raisons expliquent cette forte sensibilitĂ© du cycle de lâeau en MĂ©diterranĂ©e au changement climatique. Tout dâabord, le bassin mĂ©diterranĂ©en se trouve dans une zone de transition entre le climat tempĂ©rĂ© des latitudes moyennes et le climat plus chaud et sec de lâAfrique du Nord. Un autre facteur dâexplication provient de ses caractĂ©ristiques gĂ©ographiques, i.e. une mer semi-fermĂ©e entourĂ©e de montagnes et de rĂ©gions littorales trĂšs urbanisĂ©es. Ces facteurs climatiques, gĂ©ographiques et anthropiques contribuent aussi Ă la forte variabilitĂ© spatiale et temporelle des conditions climatiques, ocĂ©aniques et hydrologiques rencontrĂ©es en MĂ©diterranĂ©e. Lâanalyse des tendances observĂ©es des moyennes annuelles sur le dernier demi-siĂšcle montre des Ă©volutions des composantes du cycle de lâeau en MĂ©diterranĂ©e avec, globalement en MĂ©diterranĂ©e, une augmentation de la tempĂ©rature, une diminution des prĂ©cipitations et des apports des fleuves Ă la mer, et une augmentation de lâĂ©vaporation. Les projections climatiques des modĂšles globaux ou rĂ©gionaux du climat indiquent que ce rĂ©chauffement et assĂšchement va se poursuivre, avec une amplitude de ces changements qui dĂ©pend principalement aprĂšs 2050 du scĂ©nario dâĂ©mission. Les projections climatiques indiquent aussi une augmentation en frĂ©quence et intensitĂ© des vagues de chaleur. NĂ©anmoins, la distribution spatiale dĂ©taillĂ©e des changements en tempĂ©rature, et encore plus des changements en prĂ©cipitation, demeure encore incertaine. Les modĂšles de climat prĂ©voient clairement une augmentation de la tempĂ©rature de la mer en surface sous lâeffet du changement climatique, qui se propage aux couches profondes ocĂ©aniques. Il est attendu que la circulation thermohaline de la MĂ©diterranĂ©e va Ă©voluer sous lâeffet de ce rĂ©chauffement de la mer et des changements encore incertains de la salinitĂ©. Les Ă©changes de chaleur et dâeau au dĂ©troit de Gibraltar devraient aussi ĂȘtre modifiĂ©s en consĂ©quence, et donc la source de chaleur et de sel que reprĂ©sente la mer MĂ©diterranĂ©e pour lâAtlantique Nord. Il nây a cependant pas Ă ce jour de consensus entre les modĂšles sur les caractĂ©ristiques dâĂ©volution de la circulation thermohaline de la MĂ©diterranĂ©e et des Ă©changes avec lâOcĂ©an Atlantique
Utilização de simulaçÔes numéricas como apoio no estudo de precipitação na Ilha da Madeira (Portugal)
The Madeira is a small mountainous island (~740 km2) located in the North Atlantic Ocean (32°75'N and 17°00'W), and after the disaster occurred on 20 February 2010, when extreme precipitation induced flash floods and landslides in some spots of the island, efforts have been directed toward the understanding of the precipitation affecting the island. The occurrence of extreme precipitation in three seasons in the last years have raised questions mainly about the atmospheric conditions that may lead to the development of intense precipitation with high impact at the surface. Our goals in this work are to identify and describe the large- and meso- scale features associated to four periods of significant accumulated precipitation during the autumn 2012. The precipitation recorded by the Madeira meteorological network is analyzed, as well as satellite images in order to describe the characteristics of the precipitation systems that reached the Madeira in each period. The synoptic scale conditions are described thank to the 6-hourly ARPEGE operational analyses. The four periods were associated with different large-scale precipitating systems. The mesoscale environment and precipitating systems have been then studied thank to very-high resolution numerical simulations using the MESO-NH non-hydrostatic model. The numerical experiments were carried out using as initial and boundary conditions the ARPEGE analyses. The model was configured in two two-way nested domains: the larger domain with a grid spacing of 2.5 km and 600x500 points, and the inner domain, with 600x600 grid points and an horizontal resolution of 0.5 km. The simulations compared well with the rain gauge observations over the island. The simulation shows a strong impact of the mountainous island on the spatial distribution and volume of precipitation. The 500 m resolution simulation evidences the relationship between the local topography and precipitation
Chapter 3. Hydro-meteorological extremes
Les rĂ©gions mĂ©diterranĂ©ennes sont particuliĂšrement soumises aux risques hydromĂ©tĂ©orologiques, comme les pluies intenses et les crues rapides, les tempĂȘtes induisant des submersions marines et des fortes houles, les vagues de chaleur et les sĂ©cheresses favorisant les feux de forĂȘts. LâintensitĂ© et la frĂ©quence de ces Ă©vĂ©nements hydromĂ©tĂ©orologiques extrĂȘmes sont susceptibles dâĂ©voluer sous lâeffet du changement climatique. Lâanalyse de ces Ă©vĂ©nements extrĂȘmes repose sur lâobservation, lâanalyse de donnĂ©es et la modĂ©lisation numĂ©rique afin dâinterprĂ©ter et dâextrapoler les observations et de prĂ©voir les Ă©volutions Ă venir. LâĂ©tude des extrĂȘmes est cependant une tĂąche particuliĂšrement complexe. Les Ă©vĂ©nements extrĂȘmes sont rares par nature. Les bases de donnĂ©es disponibles ne sâenrichissent donc que trĂšs progressivement. Ces Ă©vĂ©nements sont par ailleurs souvent caractĂ©risĂ©s par de fortes hĂ©tĂ©rogĂ©nĂ©itĂ©s spatiales et temporelles que les rĂ©seaux de mesure existants peuvent difficilement capturer prĂ©cisĂ©ment. La mesure de valeurs exceptionnellement Ă©levĂ©es, pour lesquelles les rĂ©seaux de mesure nâont pas Ă©tĂ© conçus et ajustĂ©s, peut aussi ĂȘtre entachĂ©e dâincertitudes importantes. Tout ceci explique notre niveau de connaissance encore aujourdâhui imparfait et les conclusions parfois contradictoires des Ă©tudes scientifiques sur les Ă©volutions passĂ©es et futures. Nos connaissances ont cependant fortement progressĂ© ces derniĂšres annĂ©es grĂące Ă un certain nombre de programmes de recherche dĂ©diĂ©s et Ă la mise en place de bases de donnĂ©es partagĂ©es. Ce chapitre prĂ©sente lâĂ©tat des connaissances sur les phĂ©nomĂšnes extrĂȘmes hydro-climatiques autour de la MĂ©diterranĂ©e, leur rĂ©partition gĂ©ographique et saisonniĂšre, leurs Ă©volutions passĂ©es et Ă venir. Les questions non rĂ©solues et les incertitudes sont aussi exposĂ©es et discutĂ©es
A GPS network for tropospheric tomography in the framework of the Mediterranean hydrometeorological observatory CĂ©vennes-Vivarais (south-eastern France)
International audienceThe Mediterranean hydrometeorological observatory CĂ©vennes-Vivarais (OHM-CV) coordinates hydrometeorological observations (radars, rain gauges, water level stations) on a regional scale in southeastern France. In the framework of OHM-CV, temporary GPS measurements have been carried out for 2 months in autumn 2002, when the heaviest rainfall are expected. These measurements increase the spatial density of the existing permanent GPS network, by adding three more receivers between the Mediterranean coast and the CĂ©vennes-Vivarais range to monitor maritime source of water vapour flow feeding the precipitating systems over the CĂ©vennes-Vivarais region. In addition, a local network of 18 receivers covered an area of 30 by 30 km within the field of view of the meteorological radar. These regional and local networks of permanent and temporary stations are used to monitor the precipitable water vapour (PWV) with high temporal resolution (15 min). Also, the dense local network provided data which have been inverted using tomographic techniques to obtain the 3-D field of tropospheric water vapour content. This study presents methodological tests for retrieving GPS tropospheric observations from dense networks, with the aim of assessing the uncertainties of GPS retrievals. Using optimal tropospheric GPS retrieval methods, high resolution measurements of PWV on a local scale (a few kilometres) are discussed for rain events. Finally, the results of 3-D fields of water vapour densities from GPS tomography are analysed with respect to precipitation fields derived from a meteorological radar, showing a good correlation between precipitation and water vapour depletion areas
The 8 and 9 September 2002 flash flood event in France: a model intercomparison
Within the framework of the European Interreg
IIIb Medocc program, the HYDROPTIMET project aims
at the optimization of the hydrometeorological forecasting
tools in the context of intense precipitation within complex
topography. Therefore, some meteorological forecast models
and hydrological models were tested on four Mediterranean
flash-flood events. One of them occured in France where the
South-eastern ridge of the French âMassif Centralâ, the Gard
region, experienced a devastating flood on 8 and 9 September
2002. 24 people were killed during this event and the
economic damage was estimated at 1.2 billion euros.
To built the next generation of the hydrometeorological
forecasting chain that will be able to capture such localized
and fast events and the resulting discharges, the forecasted
rain fields might be improved to be relevant for hydrological
purposes.
In such context, this paper presents the results of the evaluation
methodology proposed by Yates et al. (2005) that highlights
the relevant hydrological scales of a simulated rain
field. Simulated rain fields of 7 meteorological model runs
concerning with the French event are therefore evaluated for
different accumulation times. The dynamics of these models
are either based on non-hydrostatic or hydrostatic equation
systems. Moreover, these models were run under different
configurations (resolution, initial conditions). The classical
score analysis and the areal evaluation of the simulated rain
fields are then performed in order to put forward the main
simulation characteristics that improve the quantitative precipitation
forecast.
The conclusions draw some recommendations on the value
of the quantitative precipitation forecasts and way to use it for
quantitative discharge forecasts within mountainous areas
Recommended from our members
The catastrophic flash-flood event of 8â9 September 2002 in the Gard region, France: a first case study for the CĂ©vennesâVivarais Mediterranean Hydrometeorological Observatory
The CĂ©vennesâVivarais Mediterranean Hydrometeorological Observatory (OHM-CV) is a research initiative aimed at improving the understanding and modeling of the Mediterranean intense rain events that frequently result in devastating flash floods in southern France. A primary objective is to bring together the skills of meteorologists and hydrologists, modelers and instrumentalists, researchers and practitioners, to cope with these rather unpredictable events. In line with previously published flash-flood monographs, the present paper aims at documenting the 8â9 September 2002 catastrophic event, which resulted in 24 casualties and an economic damage evaluated at 1.2 billion euros (i.e., about 1 billion U.S. dollars) in the Gard region, France. A description of the synoptic meteorological situation is first given and shows that no particular precursor indicated the imminence of such an extreme event. Then, radar and rain gauge analyses are used to assess the magnitude of the rain event, which was particularly remarkable for its spatial extent with rain amounts greater than 200 mm in 24 h over 5500 km2. The maximum values of 600â700 mm observed locally are among the highest daily records in the region. The preliminary results of the postevent hydrological investigation show that the hydrologic response of the upstream watersheds of the Gard and Vidourle Rivers is consistent with the marked spaceâtime structure of the rain event. It is noteworthy that peak specific discharges were very high over most of the affected areas (5â10 m3 sâ1 kmâ2) and reached locally extraordinary values of more than 20 m3 sâ1 kmâ2. A preliminary analysis indicates contrasting hydrological behaviors that seem to be related to geomorphological factors, notably the influence of karst in part of the region. An overview of the ongoing meteorological and hydrological research projects devoted to this case study within the OHM-CV is finally presented
Juvenile neuropsychiatric systemic lupus erythematosus: identification of novel central neuroinflammation biomarkers
International audienceIntroduction Juvenile systemic lupus erythematosus (j-SLE) is a rare chronic autoimmune disease affecting multiple organs. Ranging from minor features, such as headache or mild cognitive impairment, to serious and life-threatening presentations, j-neuropsychiatric SLE (j-NPSLE) is a therapeutic challenge. Thus, the diagnosis of NPSLE remains difficult, especially in pediatrics, with no specific biomarker of the disease yet validated. Objectives To identify central nervous system (CNS) disease biomarkers of j-NPSLE. Methods A 5-year retrospective tertiary reference monocentric j-SLE study. A combination of standardized diagnostic criteria and multidisciplinary pediatric clinical expertise was combined to attribute NP involvement in the context of j-SLE. Neopterin and interferon-alpha (IFN-α) protein levels in cerebrospinal fluid (CSF) were assessed, together with routine biological and radiological investigations. Results Among 51 patients with j-SLE included, 39% presented with j-NPSLE. J-NPSLE was diagnosed at onset of j-SLE in 65% of patients. No specific routine biological or radiological marker of j-NPSLE was identified. However, CSF neopterin levels were significantly higher in active j-NPSLE with CNS involvement than in j-SLE alone ( p =â0.0008). Neopterin and IFN-α protein levels in CSF were significantly higher at diagnosis of j-NPSLE with CNS involvement than after resolution of NP features (respectively p =â0.0015 and p =â0.0010) upon immunosuppressive treatment in all patients tested ( n =â10). Both biomarkers correlated strongly with each other ( R s =â0.832, p <â0.0001, n =â23 paired samples). Conclusion CSF IFN-α and neopterin constitute promising biomarkers useful in the diagnosis and monitoring of activity in j-NPSLE
HyMeX: A 10-Year Multidisciplinary Program on the Mediterranean Water Cycle
Drobinski, P. ... et. al.-- 20 pages, 10 figures, 1 table, supplement material http://journals.ametsoc.org/doi/suppl/10.1175/BAMS-D-12-00244.1HyMeX strives to improve our understanding of the Mediterranean water cycle, its variability from the weather-scale events to the seasonal and interannual scales, and its characteristics over one decade (2010â20), with a special focus on hydrometeorological extremes and the associated social and economic vulnerability of the Mediterranean territoriesHyMeX was developed by an international group of scientists and is currently funded by a large number of agencies. It has been the beneficiary of financial contributions from CNRS; MĂ©tĂ©o-France; CNES; IRSTEA; INRA; ANR; CollectivitĂ© Territoriale de Corse; KIT; CNR; UniversitĂ© de Toulouse; Grenoble UniversitĂ©s; EUMETSAT; EUMETNET; AEMet; UniversitĂ© Blaise Pascal, Clermont Ferrand; UniversitĂ© de la MĂ©diterranĂ©e (Aix-Marseille II); UniversitĂ© Montpellier 2; CETEMPS; Italian Civil Protection Department; UniversitĂ© Paris- Sud 11; IGN; EPFL; NASA; New Mexico Tech; IFSTTAR; Mercator Ocean; NOAA; ENEA; TU Delft; CEA; ONERA; IMEDEA; SOCIB; ETH; MeteoCat; Consorzio LAMMA; IRD; National Observatory of Athens; Ministerio de Ciencia e InnovaciĂłn; CIMA; BRGM; Wageningen University and Research Center; Department of Geophysics, University of Zagreb; Institute of Oceanography and Fisheries, Split, Croatia; INGV; OGS; Maroc MĂ©tĂ©o; DHMZ; ARPA Piemonte; ARPA-SIMC Emilia-Romagna; ARPA Calabria; ARPA Friuli Venezia Giulia; ARPA Liguria; ISPRA; University of Connecticut; UniversitĂ degli Studi dell'Aquila; UniversitĂ di Bologna; UniversitĂ degli Studi di Torino; UniversitĂ degli Studi della Basilicata; UniversitĂ La Sapienza di Roma; UniversitĂ degli Studi di Padova; UniversitĂ del Salento; Universitat de Barcelona; Universitat de les Illes Balears; Universidad de Castilla-La Mancha; Universidad Complutense de Madrid; MeteoSwiss; and DLR. It also received support from the European Community's Seventh Framework Programme (e.g., PERSEUS, CLIM-RUN)Peer reviewe
Nucleus accumbens D1- and D2-expressing neurons control the balance between feeding and activity-mediated energy expenditure
Accumulating evidence points to dysregulations of the Nucleus Accumbens (NAc) in eating disorders (ED), however its precise contribution to ED symptomatic dimensions remains unclear. Using chemogenetic manipulations in male mice, we found that activity of dopamine D1 receptor-expressing neurons of the NAc core subregion facilitated effort for a food reward as well as voluntary exercise, but decreased food intake, while D2-expressing neurons have opposite effects. These effects are congruent with D2-neurons being more active than D1-neurons during feeding while it is the opposite during running. Chronic manipulations of each subpopulations had limited effects on energy balance. However, repeated activation of D1-neurons combined with inhibition of D2-neurons biased behavior toward activity-related energy expenditure, whilst the opposite manipulations favored energy intake. Strikingly, concomitant activation of D1-neurons and inhibition of D2-neurons precipitated weight loss in anorexia models. These results suggest that dysregulations of NAc dopaminoceptive neurons might be at the core of EDs
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