Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution     

Bernard Barnier  Gurvan Madec  Thierry Penduff  Jean-Marc Molines  Anne-Marie Treguier  Julien Le Sommer  Aike Beckmann  Arne Biastoch  Claus Böning  Joachim Dengg  Corine Derval  Edmée Durand  Sergei Gulev  Elizabeth Remy  Claude Talandier  Sébastien Theetten  Mathew Maltrud  Julie McClean  Beverly De Cuevas 《Ocean Dynamics》2009,59(3):537-537

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Effects of hypoxia on benthic macrofauna and bioturbation in the Estuary and Gulf of St. Lawrence,Canada     

Rénald Belley  Philippe Archambault  Bjorn Sundby  Franck Gilbert  Jean-Marc Gagnon 《Continental Shelf Research》2010

The bottom water in the >300 m deep Lower St. Lawrence Estuary (LSLE) is persistently hypoxic in contrast to the normoxic bottom waters in the Gulf of St. Lawrence (GSL). We photographed the seabed at 11 stations in the Estuary and Gulf of St. Lawrence (EGSL) during the summers 2006 and 2007 and analysed the images to identify bioturbation traces (lebensspuren) and benthic macrofauna. The objective was to identify the environmental variables that influence the density and diversity of benthic macrofauna and bioturbation traces, and the differences that exist among regions with high, medium and low oxygen levels in the bottom water. The bottom water oxygen concentration is the variable that best explains the densities of total-traces as well as surface-traces. However, the density of these traces was higher in hypoxic regions than in well-oxygenated regions. The higher density of traces in the hypoxic region of the LSLE is mainly due to the activities of the surface deposit feeder Ophiura sp., which occurs in large numbers in this region. Possible explanations explored are stress behaviour of the organisms in response to hypoxia and different benthic macrofauna community structures between the hypoxic regions of the LSLE and the normoxic regions of the GSL. In the former, surface deposit feeders and low-oxygen tolerant species dominate over suspension feeders and low-oxygen intolerant species.  相似文献   

The effects of ionic strength and organic matter on virus inactivation at low temperatures: general likelihood uncertainty estimation (GLUE) as an alternative to least-squares parameter optimization for the fitting of virus inactivation models     

Jean-Marc Mayotte  Thomas Grabs  Stacy Sutliff-Johansson  Kevin Bishop 《Hydrogeology Journal》2017,25(4):1063-1076

This study examined how the inactivation of bacteriophage MS2 in water was affected by ionic strength (IS) and dissolved organic carbon (DOC) using static batch inactivation experiments at 4 °C conducted over a period of 2 months. Experimental conditions were characteristic of an operational managed aquifer recharge (MAR) scheme in Uppsala, Sweden. Experimental data were fit with constant and time-dependent inactivation models using two methods: (1) traditional linear and nonlinear least-squares techniques; and (2) a Monte-Carlo based parameter estimation technique called generalized likelihood uncertainty estimation (GLUE). The least-squares and GLUE methodologies gave very similar estimates of the model parameters and their uncertainty. This demonstrates that GLUE can be used as a viable alternative to traditional least-squares parameter estimation techniques for fitting of virus inactivation models. Results showed a slight increase in constant inactivation rates following an increase in the DOC concentrations, suggesting that the presence of organic carbon enhanced the inactivation of MS2. The experiment with a high IS and a low DOC was the only experiment which showed that MS2 inactivation may have been time-dependent. However, results from the GLUE methodology indicated that models of constant inactivation were able to describe all of the experiments. This suggested that inactivation time-series longer than 2 months were needed in order to provide concrete conclusions regarding the time-dependency of MS2 inactivation at 4 °C under these experimental conditions.  相似文献   

A developmental model of olivine morphology as a function of the cooling rate and the degree of undercooling   总被引：3，自引：2，他引：1  

Faure  François  Trolliard  Gilles  Nicollet  Christian  Montel  Jean-Marc 《Contributions to Mineralogy and Petrology》2003,145(2):251-263

We performed dynamic crystallization experiments in the CMAS system at 1 atm to investigate the evolution of the morphology of forsterite crystals as a function of cooling rate and degree of undercooling. In sections parallel to the (010) plane, we observed the evolution of the forsterite morphology from tablets to hopper (skeletal) crystals, and then to swallowtail shapes (dendritic morphology) for increased degree of undercooling. The other shapes described in the literature can be interpreted as particular sections of those three shapes. The onset of dendritic growth is due to a competition between the growth of the faces of the initial hopper crystal and dendrite overgrowths. The forsterite dendrites are formed by a succession of units which look like hopper shapes. This result has been tested by an additional set of experiments.  相似文献   

Microphytobenthic potential productivity estimated in three tidal embayments of the San Francisco Bay: A comparative study     

Jean-Marc?GuariniEmail author  James?E.?Cloern  Jody?Edmunds  Philippe?Gros 《Estuaries and Coasts》2002,25(3):409-417

In this paper we describe a three-step procedure to infer the spatial heterogeneity in microphytobenthos primary productivity at the scale of tidal estuaries and embayments. The first step involves local measurement of the carbon assimilation rate of benthic microalgae to determine the parameters of the photosynthesis-irradiance (P-E) curves (using non-linear optimization methods). In the next step, a resampling technique is used to rebuild pseudo-sampling distributions of the local productivity estimates; these provide error estimates for determining the significance level of differences between sites. The third step combines the previous results with deterministic models of tidal elevation and solar irradiance to compute mean and variance of the daily areal primary productivity over an entire intertidal mudflat area within each embayment. This scheme was applied on three different intertidal mudflat regions of the San Francisco Bay estuary during autumn 1998. Microphytobenthos productivity exhibits strong (ca. 3-fold) significant differences among the major sub-basins of San Francisco Bay. This spatial heterogeneity is attributed to two main causes: significant differences in the photosynthetic competence (P-E parameters) of the microphytobenthos in the different sub-basins, and spatial differences in the phase shifts between the tidal and solar cycles controlling the exposure of intertidal areas to sunlight. The procedure is general and can be used in other estuaries to assess the magnitude and patterns of spatial variability of microphytobenthos productivity at the level of the ecosystems.  相似文献   

Series expansions for encounter-type solutions of Hill's problem   总被引：1，自引：0，他引：1  

Michel Hénon  Jean-Marc Petit 《Celestial Mechanics and Dynamical Astronomy》1986,38(1):67-100

Hill's problem is defined as the limiting case of the planar three-body problem when two of the masses are very small. This paper describes analytic developments for encounter-type solutions, in which the two small bodies approach each other from an initially large distance, interact for a while, and separate. It is first pointed out that, contrary to prevalent belief, Hill's problem is not a particular case of the restricted problem, but rather a different problem with the same degree of generality. Then we develop series expansions which allow an accurate representation of the asymptotic motion of the two small bodies in the approach and departure phases. For small impact distances, we show that the whole orbit has an adiabatic invariant, which is explicitly computed in the form of a series. For large impact distances, the motion can be approximately described by a perturbation theory, originally due to Goldreich and Tremaine and rederived here in the context of Hill's problem.  相似文献   

A key-formula to compute the gravitational potential of inhomogeneous discs in cylindrical coordinates     

Jean-Marc Huré 《Celestial Mechanics and Dynamical Astronomy》2012,114(4):365-385

We have established the exact expression for the gravitational potential of a homogeneous polar cell??an elementary pattern used in hydrodynamical simulations of gravitating discs. This formula, which is a closed-form, works for any opening angle and radial extension of the cell. It is valid at any point in space, i.e. in the plane of the distribution (inside and outside) as well as off-plane, thereby generalizing the results reported by Durand (Electrostatique. Vol. I. Les Distributions, 1953) for the circular disc. The three components of the gravitational acceleration are given. The mathematical demonstration proceeds from the incomplete version of Durand??s formula for the potential (based on complete elliptic integrals). We determine first the potential due to the circular sector (i.e. a pie-slice sheet), and then deduce that of the polar cell (from convenient radial scaling and subtraction). As a by-product, we generate an integral theorem stating that ??the angular average of the potential of any circular sector along its tangent circle is ${\frac{2}{\pi}}$ times the value at the corner??. A few examples are presented. For numerical resolutions and cell shapes commonly used in disc simulations, we quantify the importance of curvature effects by performing a direct comparison between the potential of the polar cell and that of the Cartesian (i.e. rectangular) cell having the same mass. Edge values are found to deviate roughly like ${2 \times 10^{-3}\times N/256}$ in relative (N is the number of grid points in the radial direction), while the agreement is typically four orders of magnitude better for values at the cell??s center. We also produce a reliable approximation for the potential, valid in the cell??s plane, inside and close to the cell. Its remarkable accuracy, about ${5\times 10^{-4}\times N/256}$ in relative, is sufficient to estimate the cell??s self-acceleration.  相似文献   

Thermodynamic properties of chlorite and berthierine derived from calorimetric measurements     

Philippe Blanc  Hélène Gailhanou  Jacques Rogez  Georges Mikaelian  Hitoshi Kawaji  Fabienne Warmont  Stéphane Gaboreau  Sylvain Grangeon  Jean-Marc Grenèche  Philippe Vieillard  Claire I. Fialips  Eric Giffaut  Eric C. Gaucher  F. Claret 《Physics and Chemistry of Minerals》2014,41(8):603-615

In the context of the deep waste disposal, we have investigated the respective stabilities of two iron-bearing clay minerals: berthierine ISGS from Illinois [USA; (Al_0.975FeIII_0.182FeII_1.422Mg_0.157Li_0.035Mn_0.002)(Si_1.332Al_0.668)O₅(OH)₄] and chlorite CCa-2 from Flagstaff Hill, California [USA; (Si_2.633Al_1.367)(Al_1.116FeIII_0.215Mg_2.952FeII_1.712Mn_0.012Ca_0.011)O₁₀(OH)₈]. For berthierine, the complete thermodynamic dataset was determined at 1 bar and from 2 to 310 K, using calorimetric methods. The standard enthalpies of formation were obtained by solution-reaction calorimetry at 298.15 K, and the heat capacities were measured by heat-pulse calorimetry. For chlorite, the standard enthalpy of formation is measured by solution-reaction calorimetry at 298.15 K. This is completing the entropy and heat capacity obtained previously by Gailhanou et al. (Geochim Cosmochim Acta 73:4738–4749, 2009) between 2 and 520 K, by using low-temperature adiabatic calorimetry and differential scanning calorimetry. For both minerals, the standard entropies and the Gibbs free energies of formation at 298.15 K were then calculated. An assessment of the measured properties could be carried out with respect to literature data. Eventually, the thermodynamic dataset allowed realizing theoretical calculations concerning the berthierine to chlorite transition. The latter showed that, from a thermodynamic viewpoint, the main factor controlling this transition is probably the composition of the berthierine and chlorite minerals and the nature of the secondary minerals rather than temperature.  相似文献