Penetrative convection in the upper ocean due to surface cooling     

Benoit Cushman-Roisin 《地球物理与天体物理流体动力学》2013,107(1-2):61-91

Abstract

A new non-linear model of mixing and convection based on a modelling of two buoyant interacting fluids is applied to penetrative convection in the upper ocean due to surface cooling. In view of simple algebra, the model is one-dimensional. Dissipation is included, but no mean shear is present. A non-similar analytical solution is found in the case of a well-mixed layer bounded below by a sharp thermocline treated as a boundary layer. This solution is valid if the Richardson number, R _i , defined as the ratio of the total mixed-layer buoyancy to a characteristic rms vertical velocity, is much greater than unity. The model predicts a deepening rate proportional to R _i ^?3/4. The thermocline remains of constant thickness, and the ratio thermocline thickness to mixed-layer depth decreases as R _i ^?3/4 as the mixed layer deepens. If the surface flux is constant, the mixed-layer depth increases with time as t ^½. The vertical structure throughout the mixed layer and thermocline is given by the analytical solution, and vertical profiles of mean temperature and vertical fluxes are plotted. Computed profiles and available laboratory data agree remarkably well. Moreover, the accuracy of the simple analytical results presented here is comparable to that of sophisticated turbulence numerical models.  相似文献   

Long term high frequency sediment observatory in an alpine catchment: The Arc-Isère rivers,France     

Fabien Thollet  Christophe Rousseau  Benoit Camenen  Stephane Boubkraoui  Flora Branger  François Lauters  Julien Némery 《水文研究》2021,35(2):e14044

We present a dataset on to the Arc-Isère long-term environmental research observatory, which is part of the Rhône Basin Long Term Environmental Research Observatory. This alpine catchment located in the French Alps is characterized by high Suspended Particulate Matter (SPM) in anthropogenized valleys. Suspended Sediment Concentrations (SSC) naturally observed in the river are very high, ranging from a few tens of milligrams per litre at low flow to tens of grams per litre during major natural hydrological events (floods, debris flows) or river dam hydraulic flushes. One research objective related to this site is to better understanding the SSC dynamics along the river using a system of nested catchments (Arvan, Arc, and Isère) in order to assess both temporal and spatial dynamics. The data allow the quantification of fine sediment yields and also the evaluation of possible morphological changes due to fine sediment deposition or resuspension. Additionally, the observatory database support studies on contaminants (either dissolved or particulate contaminants). Our monitoring includes six stations with high frequency (2–30 min) streamflow, SSC measurement using turbidity sensors, and associated automatic sampling. Discharge is measured via water level measurements and a rating curve. The oldest station (Grenoble-campus) started recording discharge and concentration data from April 2006 while others stations were built between 2009 and 2011. Data are available in an online data website called ‘Base de Données des Observatoires en Hydrologie’ (Hydrological observatory database, https://bdoh.irstea.fr/ARC-ISERE/ ) with a DOI reference for the dataset. The hydrological and sediment transport time series are stored, managed and made available to a wide community with unfettered access in order to be used at their full extent. This database is used as a data exchange tool for both scientists and operational end-users and there is an associated online tool to compute integrated fluxes.  相似文献   

Recent wave climate and expected future changes in the seasonally ice-infested waters of the Gulf of St. Lawrence,Canada     

Benoit Ruest  Urs Neumeier  Dany Dumont  Eliott Bismuth  Simon Senneville  James Caveen 《Climate Dynamics》2016,46(1-2):449-466

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Early evaluation of coastal nutrient over-enrichment: new procedures and indicators     

Goberville E  Beaugrand G  Sautour B  Tréguer P 《Marine pollution bulletin》2011,62(8):1751-1761

Recent studies have provided compelling evidence for an accelerated anthropogenic impact on coastal systems, resulting in intense inputs of materials and nutrients from the continent. This has led scientists and policymakers to encourage the implementation of monitoring programmes, which have resulted in the multiplicity of datasets. However surprisingly, only a few attempts have been made to couple observations with statistical and mathematical tools to detect, as soon as the data become available perturbations in coastal systems. Here, we propose new mathematical procedures to evaluate the state of a system, based on the building of relative reference state and indicators of nutrient over-enrichment. The techniques were tested in some French coastal systems using data from the programme SOMLIT. Applied to this dataset, the multivariate procedures rapidly identified and evaluated anthropogenic nutrient anomalies from the continent on three sites (Wimereux, Roscoff and Villefranche-sur-Mer) from 1997 onwards.  相似文献   

Erratum to: Exposure of developing countries to sea-level rise and storm surges     

Susmita Dasgupta  Benoit Laplante  Siobhan Murray  David Wheeler 《Climatic change》2011,106(4):581

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Preliminary results From a partial LRTAP model based on an existing meteorological forecast model     

J. Pudykiewicz  R. Benoit  A. Staniforth 《大气与海洋》2013,51(3):267-303

Abstract

An existing state‐of‐the‐art regional meteorological model is coupled through appropriate constituent mass conservation equations to model the long‐range transport of atmospheric pollutants (LRTAP) under restrictive constraints on atmospheric chemistry and deposition. Particular emphasis is given to the importance of a good representation of turbulence and other sub grid‐scale processes in the planetary boundary layer (PBL), both in the formulation and in the interpretation of the results. The regional meteorological model provides not only forecasts of wind velocity and temperature, but also vertical diffusion profiles consistent with the evolution of its PBL. The transport in the LRTAP model is handled by computationally stable algorithms such that the time step may be chosen on the basis of accuracy rather than stability, and the chemistry is described by a simple four‐species model of the oxidation of sulphur dioxide and nitrogen dioxide. Results are presented of a sample 48‐h summer simulation over central and eastern North America, using real meteorological data and time‐averaged emission inventory data; parameters of the integration include a one‐hour time step, a horizontal resolution of 100 km and 15 variably spaced vertical levels, 10 of which are contained in the lower one third of the atmosphere. It is argued that despite the simplicity of the chemistry, the results are qualitatively realistic and the high impact of the PBL processes on LRTAP is evident. For this particular simulation, it is interesting to note the existence of a region over Nova Scotia where the deposition of sulphates is significantly greater than that which could be expected from local sources. This is interpreted as being due to the confluence of two flows that pass over two different centres of high emission ofSC>2, andas being evidence of the model's ability to qualitatively model LRTAP.  相似文献   

Trophic ecology of mullets during their spring migration in a European saltmarsh: A stable isotope study     

Benoit Lebreton  Pierre Richard  Emmanuel P. Parlier  Gaël Guillou  Grard F. Blanchard 《Estuarine, Coastal and Shelf Science》2011,91(4):106

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Trophic status of earthen ponds used for semi-intensive shrimp (Litopenaeus stylirostris, Stimpson, 1874) farming in New Caledonia (Pacific Ocean)     

Pusceddu A  Della Patrona L  Beliaeff B 《Marine environmental research》2011,72(4):160-171

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Thermal Conductivity of Argillaceous Rocks: Determination Methodology Using In Situ Heating Tests   总被引：1，自引：1，他引：0  

Benoit Garitte  Antonio Gens  Jean Vaunat  Gilles Armand 《Rock Mechanics and Rock Engineering》2014,47(1):111-129

This study focuses on the characterisation of thermal conductivity for three potential host rocks for radioactive waste disposal. First, the heat conduction process is reviewed on the basis of an analytical solution and key aspects related to anisotropic conduction are discussed. Then the existing information on the three rocks is summarised and a broad uncertainty range of thermal conductivity is estimated based on the mineralogical composition. Procedures to backanalyse the thermal conductivity on the basis of in situ heating tests are assessed and a methodology is put forward. Finally, this methodology is used to estimate the impact of experimental uncertainties and applied to the four in situ heating tests. In the three potential host rocks, a clear influence of the bedding planes was identified and anisotropic heat conduction was shown to be necessary to interpret the observed temperature field. Experimental uncertainties were also shown to induce a larger uncertainty on the anisotropy ratio than on the equivalent thermal conductivity defined as the geometric mean of the thermal conductivity in the three principal directions.  相似文献   

Modified Newtonian dynamics in the Milky Way     

Benoit Famaey  James Binney 《Monthly notices of the Royal Astronomical Society》2005,363(2):603-608

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