Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Within the framework of the international field campaign COPS (Convective and Orographically induced Precipitation Study), a large suite of state-of-the-art meteorological instrumentation was operated, partially combined for the first time. This includes networks of in situ and remote-sensing systems such as the Global Positioning System as well as a synergy of multi-wavelength passive and active remote-sensing instruments such as advanced radar and lidar systems. The COPS field phase was performed from 01 June to 31 August 2007 in a low-mountain area in southwestern Germany/eastern France covering the Vosges mountains, the Rhine valley and the Black Forest mountains. The collected dataset covers the entire evolution of convective precipitation events in complex terrain from their initiation, to their development and mature phase until their decay. Eighteen Intensive Observations Periods with 37 operation days and eight additional Special Observations Periods were performed, providing a comprehensive dataset covering different forcing conditions. In this article, an overview of the COPS scientific strategy, the field phase, and its first accomplishments is given. Highlights of the campaign are illustrated with several measurement examples. It is demonstrated that COPS research provides new insight into key processes leading to convection initiation and to the modification of precipitation by orography, in the improvement of quantitative precipitation forecasting by the assimilation of new observations, and in the performance of ensembles of convection-permitting models in complex terrain.
ISSN: 0035-9009

hal-00565513
https://hal.archives-ouvertes.fr/hal-00565513
DOI : 10.1002/qj.752

Éditeur(s) : HAL CCSD
Résumé : The field campaign on the Sète coast deployed during the winter 2009 was used to understand the hydrodynamics on a double barred beach in the surf zone during storm periods. The large set of measurements collected at several position and depth were also useful to improve the 3D circulation model Symphonie that takes into account the atmospherics and wave forcings. Once implemented on the beach and supplemented with some additional parameterizations concerning the roller effects and the bottom friction, the model was tuned and validated in the surf zone. The role of the different processes was then analysed. Thus, the roller and the bottom friction are of primary importance in the dynamics of the circulation. Thanks to its 3D nature and once associated with a sediment transport model and a morphodynamic model, Symphonie will offer a good representation of the sediment transport.
Coastal Dynamics 2013
Arcachon, France

hal-00855035
https://hal.archives-ouvertes.fr/hal-00855035

Éditeur(s) : HAL CCSD Météo et Climat
Résumé : International audience
D'initiative française, le projet international HyMeX a pour objectif d'améliorer la compréhension du cycle de l'eau en Méditerranée, de sa variabilité, de l'échelle de l'événement météorologique aux échelles saisonnières et interannuelles, et de ses caractéristiques sur une décennie, dans un contexte de changement global. Le projet est motivé par le rôle déterminant des processus de mésoéchelle, couplés entre l'atmosphère, la mer et la terre, sur la variabilité du système climatique et sur le déclenchement d'événements hydrométéorologiques extrêmes (précipitations et inondations, vents forts et convection océanique, canicules et sécheresses). Le projet vise enfin à évaluer les conséquences de ces événements extrêmes sur la vulnérabilité sociale et économique de cette région et sa capacité d'adaptation.
ISSN: 0026-1181

hal-00828758
https://hal.archives-ouvertes.fr/hal-00828758
https://hal.archives-ouvertes.fr/hal-00828758/document
https://hal.archives-ouvertes.fr/hal-00828758/file/meteo_2013_80_23%20%281%29.pdf
DOI : 10.4267/2042/48792

Éditeur(s) : HAL CCSD Météo et Climat
Résumé : International audience
Les risques hydrométéorologiques sont au coeur du programme de recherche HyMeX sur le cycle de l'eau en Méditerranée. HyMeX a pour ambition d'améliorer leur prévision, de mieux connaître leur variabilité à l'échelle pluriannuelle et de renseigner sur leur évolution, dans le contexte du changement climatique. À cette fin, deux campagnes de mesures dédiées à ces événements extrêmes (SOP1 : pluies intenses et crues rapides ; SOP2 : vents forts et formation d'eaux denses) sont organisées en Méditerranée nord-occidentale, entre septembre 2012 et mars 2013.
ISSN: 0026-1181

hal-00829760
https://hal.archives-ouvertes.fr/hal-00829760
DOI : 10.4267/2042/48793

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We have measured simultaneously the methane (CH4) and carbon dioxide (CO2) surface concentrations and water–air fluxes by floating chambers (FC) in the Petit-Saut Reservoir (French Guiana) and its tidal river (Sinnamary River) downstream of the dam, during the two field experiments in wet (May 2003) and dry season (December 2003). The eddy covariance (EC) technique was also used for CO2 fluxes on the lake. The comparison of fluxes obtained by FC and EC showed little discrepancies mainly due to differences in measurements durations which resulted in different average wind speeds. When comparing the gas transfer velocity (k600) for a given wind speed, both methods gave similar results. On the lake and excluding rainy events, we obtained an exponential relationship between k600 and U10, with a significant intercept at 1.7 cm h− 1, probably due to thermal effects. Gas transfer velocity was also positively related to rainfall rates reaching 26.5 cm h−1 for a rainfall rate of 36 mm h− 1. During a 24-h experiment in dry season, rainfall accounted for as much as 25% of the k600. In the river downstream of the dam, k600 values were 3 to 4 times higher than on the lake, and followed a linear relationship with U10.
ISSN: 0924-7963

hal-00519502
https://hal.archives-ouvertes.fr/hal-00519502
DOI : 10.1016/j.jmarsys.2006.03.019

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Holocene Lake Mega-Chad (LMC) was the largest late Quaternary water-body in Africa. The development of this giant paleo-lake is related to a northward shift of the isohyetes interpreted as evidence for an enhanced Monsoon (African Humid Period). Numerous preserved coastal features have been described all around the LMC shore. Such features reveal the main paleo-hydrodynamical tendencies. In the context of a closed water-body like LMC, hydrodynamics are forced mainly by winds. We use a three-dimensional numerical model (SYMPHONIE) to simulate the mean hydrodynamics in LMC under both Harmattan-like (northeasterly trade winds) and Monsoon-like (southwesterly winds) forcings. The northern part of LMC displays coastal features, such as sand spits, that are consistent with the simulations forced by Harmattan-like winds. Geomorphic features related to Monsoon-driven hydrodynamics are not clearly expressed. They could have developed during the early stage of LMC but subsequently reworked. At the time of sand-spit building, Harmattan-like driven hydrodynamics prevailed and related coastal features were preferentially preserved in the sedimentary record.
ISSN: 0033-5894

hal-00475633
https://hal.archives-ouvertes.fr/hal-00475633
DOI : 10.1016/j.yqres.2009.10.010

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
We develop and implement a new method to take into account the impact of waves into the 3-D circulation model SYMPHONIE (Marsaleix et al., 2008, 2009a), following the simplified equations of Bennis et al. (2011) which use glm2z-RANS theory (Ardhuin et al., 2008b). These adiabatic equations are completed by additional parameterizations of wave breaking, bottom friction and wave-enhanced vertical mixing, making the forcing valid from the surf zone through to the open ocean. The wave forcing is performed by wave generation and propagation models WAVEWATCH III® (Tolman, 2008, 2009; Ardhuin et al., 2010) and SWAN (Booij et al., 1999). The model is tested and compared with other models for a plane beach test case, previously tested by Haas and Warner (2009) and Uchiyama et al. (2010). A comparison is also made with the laboratory measurements of Haller et al. (2002) of a barred beach with channels. Results fit with previous simulations performed by other models and with available observational data. Finally, a realistic case of energetic waves travelling over a coast of the Gulf of Lion (in the northwest of the Mediterranean Sea) for which currents are available at different depths as well as an accurate bathymetric database of the 0-10 m depth range, is then simulated. A grid nesting approach is used to account for the different forcings acting at different spatial scales. The simulation coupling the effects of waves and currents is successful to reproduce the powerful northward littoral drift in the 0-15 m depth zone. More precisely, two distinct cases are identified: when waves have a normal angle of incidence with the coast, they are responsible for complex circulation cells and rip currents in the surf zone, and when they travel obliquely, they generate a northward littoral drift. These features are more complicated than in the test cases, due to the complex bathymetry and the consideration of wind and non-stationary processes. Wave impacts in the inner shelf are less visible since wind and regional circulation seem to be the predominant forcings. Besides, a discrepancy between model and observations is noted at that scale, possibly linked to an underestimation of the wind stress. Lastly, this three-dimensional method allows a good representation of vertical current profiles and permits to calculate the shear stress associated with wave and current. Future work will focus on the combination with a sediment transport model.
ISSN: 1812-0806

hal-00766548
https://hal.archives-ouvertes.fr/hal-00766548
https://hal.archives-ouvertes.fr/hal-00766548/document
https://hal.archives-ouvertes.fr/hal-00766548/file/os-8-657-2012.pdf
DOI : 10.5194/osd-8-2417-2011

Éditeur(s) : HAL CCSD Météo et Climat
Résumé : International audience
Le premier volet du projet Cyprim vise à mieux identifier les précurseurs des cyclogenèses et des précipitations intenses en région méditerranéenne. Cet article en présente les principaux résultats. Il est question des ingrédients météorologiques à l'origine de ces systèmes, de la grande à la mésoéchelle, des causes des fortes intensités, localisations et parfois stationnarité des récipitations associées. Le coeur de l'article présente des méthodes d'identification des anomalies de tourbillon potentiel liées à l'occurrence d'événements précipitants intenses et dresse une climatologie de ces anomalies. Les perspectives d'exploitation de cette information pour améliorer la qualité des prévisions sont évoquées. ENGLISH VERSION: The first part of the CYPRIM project (Cyclogenesis and intense precipitations in the Mediterranean region) aims at a better identification of the precursor structures of cyclogenesis and heavy precipitation in the Mediterranean region. This article presents the main results. It mentions the meteorological ingredients from which these systems originate from the large to themesoscale, the reasons for large intensities, the localization and sometimes stationarity of the associated precipitations. The heart of the article shows methods for identifiying potential vorticity anomalies involved in the occurrence of heavy precipitation events and sets up a climatology of these anomalies.The perspectives of the usefulness of this information for improving forecast quality are discussed.
ISSN: 0026-1181

insu-00448250
https://hal-insu.archives-ouvertes.fr/insu-00448250
DOI : 10.4267/2042/28828

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
In the mid-afternoon of 15 July 2007, during the Convective and Orographically induced Precipitation Study (COPS), in a very warm and dry environment, an isolated, short-lived, deep convective system developed over the southern Black Forest. Most of the high-resolution, convection-permitting models involved in COPS were unable to capture this event whereas the Meso-NH forecast was quite skilful. To assess the Meso-NH performance further, the model results were carefully checked against the various and numerous COPS observations. In full agreement with clear-air radar observations, model results underlined the triggering role of a low-level convergence line that developed in the lee of the Feldberg. The main departure from the observations was found to be in the low-level moisture fields, which appeared significantly moister in the model than in the observations and also slightly moister than in the other models. Sensitivity studies showed that this departure from the observations was strongly controlled by the initial surface moisture conditions. When the surface moisture was reduced by 20% or replaced by the value derived from a different analysis, the evolution of the planetary boundary layer was more accurately represented while the storm evolution was still correctly captured. These results demonstrate that the quality of the initial forecast cannot be ascribed to the moist bias of the model. It could therefore be hypothesized that the key parameters for a satisfactory forecast of this event lie more in the ability of the model to reproduce the dynamical forcing accurately than in the characteristics of the air-mass instability.
ISSN: 0035-9009

hal-00554400
https://hal.archives-ouvertes.fr/hal-00554400
DOI : 10.1002/qj.710

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The Convective and Orographically-driven Precipitation Study (COPS) carried out in summer 2007 over northeastern France and southwestern Germany provided a fairly comprehensive description of the low-troposphere water-vapour field, thanks in particular to the deployment of two airborne differential absorption lidar systems. These lidar observations were assimilated using the 3D-Var assimilation system of the Application of Research to Operations at MEsoscale (AROME) numerical weather prediction mesoscale model. The assimilation was carried out for the period 4 July-3 August by running a three-hour forward intermittent assimilation cycle. First, the impact of the lidar observations was assessed by comparing the analyses with a set of more than 200 independent soundings. The lidar observations were found to have a positive impact on the analyses by reducing the dry bias in the first 500 m above ground level and by diminishing the root-mean-square error by roughly 15% in the first km. Then the impact of the lidar observations was assessed by comparing the precipitation forecasts (obtained with and without the lidar observations for the period 15 July-2 August) with the gridded precipitation observations provided by the Vienna Enhanced Resolution Analysis. In general, the impact was found to be positive but not significant for the 24 h precipitation and positive and significant for the 6 h precipitation, with an improvement lasting up to 24 h. Some selected case studies show that the improvement was obtained through a better depiction of convection initiation or through a more accurate positioning of the precipitation systems
ISSN: 0035-9009

hal-00659497
https://hal.archives-ouvertes.fr/hal-00659497
DOI : 10.1002/qj.1864

Éditeur(s) : HAL CCSD
Résumé : The sandy coasts of Languedoc-Roussillon are a zone vulnerable to erosion and flooding. These hazards are generally associated with a combination of natural factors such as waves, wind, rising sea levels and the importance of sediment supply, and are therefore worsened during storms. For the management of such risks, a better knowledge of the hydrodynamic phenomena occuring from the surf zone through to the coastal scale is essential. This need led to the development of a numerical modelling platform consisting of the 3D ocean circulation model Symphonie, usually dedicated to regional and coastal scales, which was modified to include the wave forcing, modeled by the WaveWatch III or Swan models. Using this platform the entire littoral and coastal regions can be accurately represented. The model was tested in several academic cases. Measurements on the barred beach of Sète during the winter of 2008-2009 served to refine the model, which is able to successfully reproduce the characteristics of the currents in coastal areas, drifts or rip currents over more complex bathymetries and also the vertical profiles of currents. To validate the model on the inner-shelf, we compared the simulations with measurements taken during a winter storm in 2004 around the mouth of the Têt river, as well as during storms in 2007 and 2008 in the Gulf of Aigues-Mortes. Currents are generally well reproduced. However, the scope of wave action seems limited to a depth of 30m. The characteristics of our model allow a good reproduction of the currents at all scales and the 3D nature of the model permits a more precise calculation of the shear stress and bottom current responsible, respectively, for the suspension and advection of sediments.
Le littoral sableux du Languedoc-Roussillon est un système vulnérable aux risques d'érosion et de submersion. Ces aléas sont liés à la conjonction des facteurs naturels que sont les vagues, vent, élévation du niveau de la mer et apports sédimentaires et sont donc aggravés en période de tempête. En vue d'une gestion des risques, une meilleure connaissance des phénomènes hydrodynamiques de l'échelle littorale à l'échelle côtière est essentielle. Ce travail a conduit à la réalisation d'une plateforme de modélisation numérique composée du modèle de circulation océanique 3D Symphonie, traditionnellement dédié aux échelles régionales et côtières, qui a été modifié pour inclure le forçage par les vagues, modélisées par les modèles Wavewatch III ou Swan, et ainsi étendre sa validité au littoral. Le modèle a été testé sur des cas académiques littoraux. Des mesures sur la plage à double barres de Sète pendant l'hiver 2008-2009, ont également servi à parfaire le modèle qui reproduit ainsi avec succès les caractéristiques des courants en zone littorale : la dérive, les courants sagittaux sur des bathymétries plus complexes et les profils verticaux des courants. Pour valider le modèle à des échelles plus côtières, nous avons confronté ses résultats à des mesures réalisées pendant une tempête hivernale en 2004 aux alentours de l'embouchure de la Têt, mais également sur des tempêtes de 2007 et 2008 dans le Golfe d'Aigues-Mortes. Les courants sont globalement bien reproduits. Les zones d'action des vagues semblent limitées aux zones de profondeur inférieure à 30 m. Notre modèle autorise une reproduction correcte des courants à toutes les échelles et sa nature 3D permet un calcul plus précis de la tension de cisaillement de fond et du courant près du fond, responsables respectivement de la mise en suspension et de l'advection des sédiments.
https://tel.archives-ouvertes.fr/tel-00680405

tel-00680405
https://tel.archives-ouvertes.fr/tel-00680405
https://tel.archives-ouvertes.fr/tel-00680405v2/document
https://tel.archives-ouvertes.fr/tel-00680405/file/2011_MICHAUD.pdf

Éditeur(s) : HAL CCSD Météo et Climat
Résumé : International audience
The Convective and Orographically- induced Precipitation Study (COPS) is a coordinated international project, comprised of an observational field campaign and a research programme aiming to advance the quality of fore- casts of orographically-induced pre- cipitation by four-dimensional obser- vations and modelling of its life cycle. The COPS field campaign took place during June-July-August 2007 over eastern France and south-western Germany. Its main objective was to provide an unprecedented comprehen- sive set of in situ and remotely-sensed meteorological observations of the entire depth of the troposphere. After a short overview of the project, the paper focuses on the French contribution to the COPS field phase, describes the experimental setup and highlights some key observations.
L’étude des précipitations convectives induites par l’orographie (Cops selon l’acronyme anglais) est un projet inter- national coordonné qui comprend une campagne d’observations de terrain et un programme scientifique et qui vise à améliorer la qualité des prévisions des précipitations orographiques convectives à la fois par l’observation quadridimensionnelle et la modélisa- tion de leur cycle de vie. La campagne de terrain s’est déroulée en juin-juillet- août 2007 sur l’est de la France et le sud-ouest de l’Allemagne. Son objectif majeur était de fournir un jeu d’obser- vations météorologiques, in situ et à distance, aussi complet que possible et sur toute la profondeur de la colonne troposphérique.Après une brève revue d’ensemble du projet, l’article se concentre sur la contribution française à la campagne Cops, décrit le dispositif expérimental mis en œuvre et met en valeur quelques observations clés.
ISSN: 0026-1181

insu-01504075
https://hal-insu.archives-ouvertes.fr/insu-01504075
https://hal-insu.archives-ouvertes.fr/insu-01504075/document
https://hal-insu.archives-ouvertes.fr/insu-01504075/file/meteo_2009_64_32.pdf
DOI : 10.4267/2042/23632

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : While oceanic circulation in the Gulf of Lion (GoL) has often been studied in calm weather or with northerly winds (Tramontane or Mistral) through observations and numerical circulation models, few studies have focused on southeasterly storm events. Yet, correct representation of the circulation during storms is crucial if the suspension of sediments is to be correctly modelled throughout the Gulf. The purpose of this paper is to describe the hydrodynamics in the Gulf of Aigues-Mortes (NW of the GoL) during the storm of 18 February 2007 by using a set of data from an ADCP station placed at a depth of 65 m on the sea bed off the coast at Sète, supplemented by the ocean circulation model SYMPHONIE. This storm was characterized by a moderate south-easterly wind (15 m . s−1) and waves of up to 5 m of significant height at its apex. At the ADCP, strong currents of up to 0.8 m . s−1 near the surface and 0.5 m . s−1 near the bottom were recorded, parallel to the coast, flowing towards the south-west. The simulated currents were widely underestimated, even taking the effect of waves into account in the model. It was suspected that the representation of the wind in the atmospheric model was an underestimation. A new simulation was therefore run with an arbitrarily chosen stronger wind and its results were in much better agreement with the measurements. A simplified theoretical analysis successfully isolated the wind-induced processes, responsible for the strong currents measured during the apex and the strong vertical shear that occurred at the beginning of the storm. These processes were: 1/ the barotropic geostrophic current induced by a wind parallel to the coast and 2/ the Ekman spiral. The duration of the storm (about 36 h at the apex) explains the continuous increase of the current as predicted by the theory. The frictionally induced Ekman transport explains the current shear in the surface layer in the rising stage of the storm, and the addition of high waves and strong wind at the apex is more in favour of strong vertical mixing in the surface layer.
ISSN: 1631-0713

hal-00908200
https://hal.archives-ouvertes.fr/hal-00908200
DOI : 10.1016/j.crte.2013.07.001

Éditeur(s) : HAL CCSD Elsevier
Résumé : The Gulf of Aigues-Mortes (NW Mediterranean Sea) is a midshelf zone whose scale is an intermediate between the nearshore scale (0–10 m depth) and the coastal scale (including the whole continental shelf). Its hydrodynamics is investigated for the first time. ADCP, CTD and thermosalinograph data were collected during three short cruises (HYGAM; March 6–7, 20–21, April 5–6, 2005). They were scheduled approximately every 15 days to sample the gulf circulation under different weather conditions. Moreover, the cruise data were used to validate the Symphonie model, a 3D primitive equations circulation model. The circulation features displayed by in situ data were well reproduced by Symphonie. A downscaling modelling approach was implemented, the largest scale being obtained by the replay of the MFSTEP regional model of the North-Western Mediterranean Sea. The analysis, closely coupling in situ measurements and model results, provides information that would not have been obtained using data separately. The great variability of the oceanic circulation at this scale is well evidenced. Winds are the main forces, not only locally but also at a larger scale. North winds generate coherent structures interacting with the general Mediterranean circulation. The explanation of the induced currents is then not straightforward, some of them being, for example, northward. South and southeast winds reinforce the sloping surface, the latter allowing the geostrophic equilibrium with longshore currents. This study, focused on the end of winter 2004–2005, also enhances the heat fluxes from offshore to nearshore, as well as the initiation of shelf dense waters. The knowledge of the midshelf oceanic circulation is then applied to run a numerical experiment which describes both the dispersion of a fictive contaminant from a point S (at the centre of the GAM), and evaluates the risk of contamination of the beaches along the GAM shores.
ISSN: 0278-4343

hal-00196620
https://hal.archives-ouvertes.fr/hal-00196620
DOI : 10.1016/j.csr.2007.06.006

Éditeur(s) : HAL CCSD Springer-Verlag
ISSN: 0390-5551

hal-00196630
https://hal.archives-ouvertes.fr/hal-00196630
DOI : 10.1393/ncc/i2006-10239-y

Éditeur(s) : HAL CCSD
Résumé : Biogenic volatile organic compound (BVOCs) emissions play an important role in regional air quality and global atmospheric chemistry. In addition, these natural VOC emissions serve important biological functions including attracting and repelling pollinators and herbivores. Some biological organisms use ambient air as a communication medium and the oxidation of these compounds brings about the concentration gradients sensed by insects and other organisms. Isoprene is the predominant BVOC emitted by vegetation and tropical forests are the dominant global source. This compound is very reactive in the atmosphere and contributes to the reactions that control tropospheric oxidant concentrations and thus the concentrations and lifetimes of longer-lived species. This paper presents a study on the seasonal variations in isoprene and some other significant BVOCs such as µ-pinene, µ-pinene, limonene, e-µ ocimene and longifolene, measured at the Guyaflux Tower located in a wet tropical forest in Paracou French Guiana (5o16´54´´N, 52o54´44´´W), during the year of 2011, using the Relaxed Eddy Accumulation technique at approximately 20 meters high above the canopy. The results show a lower concentration of isoprene during the month of February and March which correspond to the wet season with an average of 0,545 µg/m3 and 0,341 µg/m3, respectively followed by a slight increase in middle April (still wet season) and a higher concentration later in mid-June. The same behavior was observed for µ-pinene with higher concentrations for the same periods as isoprene however with a smaller increase. All the other compounds had concentrations below 1 µg/m3during the whole year: The monoterpene, e-µ ocimene, was observed and is known as a stress compound but the vegetation at the site did not face any known severe stress condition such as excessive drought or flooding. Concerning the fluxes, the results showed that just a small amount of BVOCs were deposited by wet or dry process and the majority of them were released in the atmosphere. Isoprene was by far the biogenic volatile organic compound with the highest concentration and flux, followed by alpha-pinene. The lowest concentration and flux rate for all the studied compounds was observed during the months of March and late July and beginning of August indicating a lower production of those BVOCs by vegetation during those periods. Previous limited studies in Amazonia and the Congo suggested that a higher concentration and flux rate of isoprene and µ-pinene should be expected during the dry season with lower emissions during the wet season, which is in relative agreement with what was observed at this tropical forest site in French Guiana. The exceptions were observed in April and June which correspond to a long wet period in which the concentration of isoprene and µ-pinene increased more than it was expected for this time of the year. The observations will be compared to output from the global chemistry transport model CAM-chem, which includes the MEGAN biogenic emissions model.
10th EGU General Assembly
vienne, Austria

hal-01204214
https://hal.archives-ouvertes.fr/hal-01204214
PRODINRA : 276525

Éditeur(s) : HAL CCSD
Résumé : For operational forecasts anticipate convective inhibition processes is as important than convective initiation processes. Based on the 15th July 2007 case study this work shows how the morning shallow convection over the Vosges is inhibited while it develops over the Black Forest. This case occurs during IOP 8b of the Convective and Orographically-Induced Precipitation Study (COPS). This international field campaign took place during the summer of 2007 over the Vosges, the Rhine Valley and the Black-Forest. The aim of this intensive observation campaign was to study various phases of convection and convective environment and improve quantitative precipitation forecasts. Thanks to GPS tomography data the study show the differences of low-level water-vapor variability between Vosges and Black-Forest. The analysis of ground based and airborne lidar data suggests the importance of dry air layers advected from the south and the influence of the mountains and diurnal cycle of mountain breeze which interfere strongly with these layers preventing the dry air to reach the eastern side of the mountain and the Black Forest. This dynamics is confirmed by models, wind profiler and radiosounding data. So we show how the inhibition of the convection over the Vosges during this case study can be explained with the water vapor variability due to advection and local boundary layer processes.
31st ICAM (International Conference on Alpine Meteorology)
Aviemore, United Kingdom

hal-00668829
https://hal.archives-ouvertes.fr/hal-00668829

Éditeur(s) : HAL CCSD
Résumé : In the bay of Aigues-Mortes, the managers of the co astal cities try to preserve the socio-economic and patrimonial stakes against the coastal hazards, such as contamination, storm surge and erosion. In this context, a massive beach nourishment of sand (1 million of m3 for 10km of coastline) was made at the beginning of year 2008 to reduce erosion. The REPBAM project (REchargements et Panaches sédiment aires dans la Baie d'Aigues-Mortes) aims to qualify and quantify by in-situ measurements and numerical modelling: 1. the geomorphological evolution of this modified coast and 2. the impact of the sediment's resuspension on the coastal ecosystems, in particular the one of the Posidonia oceanica seagrass. A numerical modelling "wave/current/sediment" is first implemented for December 2008. Nested and curvilinear grids allow a very high resolution for the beach area but also include the inner shelf where the seagrasses are located. Hydrodynamic and topo-bathymetric measurements were acquired from January to May 2012. Model and measurements results show the same trends during storms: strong currents, seaward migrationof the innerbar, sediment resuspension and turbid on the inner shelf.
Coastal Dynamics 2013
Arcachon, France

hal-00908082
https://hal.archives-ouvertes.fr/hal-00908082