Uniwavelength lidar sensitivity to spherical aerosol microphysical properties for the interpretation of Lagrangian stratospheric observations     

Julien Jumelet  Christine David  Slimane Bekki  Philippe Keckhut 《Journal of Atmospheric and Solar》2009,71(1):121-131

The determination of stratospheric particle microphysical properties from multiwavelength lidar, including Rayleigh and/or Raman detection, has been widely investigated. However, most lidar systems are uniwavelength operating at 532 nm. Although the information content of such lidar data is too limited to allow the retrieval of the full size distribution, the coupling of two or more uniwavelength lidar measurements probing the same moving air parcel may provide some meaningful size information. Within the ORACLE-O3 IPY project, the coordination of several ground-based lidars and the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) space-borne lidar is planned during measurement campaigns called MATCH-PSC (Polar Stratospheric Clouds). While probing the same moving air masses, the evolution of the measured backscatter coefficient (BC) should reflect the variation of particles microphysical properties. A sensitivity study of 532 nm lidar particle backscatter to variations of particles size distribution parameters is carried out. For simplicity, the particles are assumed to be spherical (liquid) particles and the size distribution is represented with a unimodal log-normal distribution. Each of the four microphysical parameters (i.e. log-normal size distribution parameters, refractive index) are analysed separately, while the three others are remained set to constant reference values. Overall, the BC behaviour is not affected by the initial values taken as references. The total concentration (N₀) is the parameter to which BC is least sensitive, whereas it is most sensitive to the refractive index (m). A 2% variation of m induces a 15% variation of the lidar BC, while the uncertainty on the BC retrieval can also reach 15%. This result underlines the importance of having both an accurate lidar inversion method and a good knowledge of the temperature for size distribution retrieval techniques. The standard deviation (σ) is the second parameter to which BC is most sensitive to. Yet, the impact of m and σ on BC variations is limited by the realistic range of their variations. The mean radius (r_m) of the size distribution is thus the key parameter for BC, as it can vary several-fold. BC is most sensitive to the presence of large particles. The sensitivity of BC to r_m and σ variations increases when the initial size distributions are characterized by low r_m and large σ. This makes lidar more suitable to detect particles growing on background aerosols than on volcanic aerosols.  相似文献   

Pilot Point Optimization of Mining Boundaries for Lateritic Metal Deposits: Finding the Trade-off Between Dilution and Ore Loss     

Dagasan  Yasin  Renard  Philippe  Straubhaar  Julien  Erten  Oktay  Topal  Erkan 《Natural Resources Research》2019,28(1):153-171

Natural Resources Research - Geological contacts in lateritic metal deposits (footwall topographies) often delineate the orebody boundaries. Spatial variations seen in such contacts are frequently...  相似文献   

Tides in a body librating about a spin–orbit resonance: generalisation of the Darwin–Kaula theory     

Julien Frouard  Michael Efroimsky 《Celestial Mechanics and Dynamical Astronomy》2017,129(1-2):177-214

The Darwin-Kaula theory of bodily tides is intended for celestial bodies rotating without libration. We demonstrate that this theory, in its customary form, is inapplicable to a librating body. Specifically, in the presence of libration in longitude, the actual spectrum of Fourier tidal modes differs from the conventional spectrum rendered by the Darwin–Kaula theory for a nonlibrating celestial object. This necessitates derivation of formulae for the tidal torque and the tidal heating rate, that are applicable under libration. We derive the tidal spectrum for longitudinal forced libration with one and two main frequencies, generalisation to more main frequencies being straightforward. (By main frequencies we understand those emerging due to the triaxiality of the librating body.) Separately, we consider a case of free libration at one frequency (once again, generalisation to more frequencies being straightforward). We also calculate the tidal torque. This torque provides correction to the triaxiality-caused physical libration. Our theory is not self-consistent: we assume that the tidal torque is much smaller than the permanent-triaxiality-caused torque, so the additional libration due to tides is much weaker than the main libration due to the permanent triaxiality. Finally, we calculate the tidal dissipation rate in a body experiencing forced libration at the main mode, or free libration at one frequency, or superimposed forced and free librations.  相似文献   

Petroleum accumulation and leakage in a deeply buried carbonate reservoir,Níspero field (Mexico)     

Julien Bourdet  Jacques Pironon  Gilles Levresse  Jordi Tritlla 《Marine and Petroleum Geology》2010

The filling history of the Níspero deeply buried Lower Cretaceous carbonate reservoir (below 4000 m) from the south part of Gulf of Mexico was studied using a combination of data from petrography, stable isotopes and fluid inclusions and compared with a one-dimensional burial model to derive timing.  相似文献   

Zooplankton community structure in a highly turbid environment (Charente estuary,France): Spatio-temporal patterns and environmental control   总被引：1，自引：0，他引：1  

Julien Modéran  Pierre Bouvais  Valérie DavidSandrine Le Noc  Benoit Simon-BouhetNathalie Niquil  Pierre MiramandDenis Fichet 《Estuarine, Coastal and Shelf Science》2010

Zooplankton assemblages were studied from January 2007 to January 2008 along the salinity gradient of the Charente estuary (France). A Lagrangian survey was performed monthly at five sampling stations defined by salinity (freshwater, 0.5, 5, 15 and 25) in order to collect zooplankton and measure the main environmental parameters (concentrations of suspended particulate matter, particulate organic carbon, chlorophyll a and phaeopigments). A combination of multivariate cluster analysis, species indicator index and canonical correspondence analysis was used to relate the spatio-temporal patterns of the zooplankton assemblages with environmental drivers. The estuary was divided into three different zones by means of environmental parameters while four zooplankton assemblages were identified along the salinity gradient. The Charente estuary appeared as one of the most turbid systems in Europe, with suspended particulate matter (SPM) concentration reaching 3.5 g l⁻¹ in the Maximum Turbidity Zone (MTZ). Algal heterotrophy and microphytobenthos resuspension from the wide mudflats could be responsible for the relatively high chlorophyll a concentrations measured within this MTZ. Salinity and SPM affected significantly the spatial distribution of zooplankton species while temperature and river flow seemed to control their temporal variations. From a zooplanktonic viewpoint, the highly turbid Charente estuary seemed to match an “ecotone–ecocline” model: the succession of species assemblages along the salinity gradient matched the concept of ecocline while the MTZ, which is a stressful narrow area, could be considered as an ecotone. Although such ecoclinal characteristics seemed to be a general feature of estuarine biocenoses, the ecotone could be more system-specific and biological compartment-specific.  相似文献   

The mesoscale variability in the Caribbean Sea. Part I: Simulations and characteristics with an embedded model     

Julien Jouanno  Julio Sheinbaum  Bernard Barnier  Jean-Marc Molines  Laurent Debreu  Florian Lemari 《Ocean Modelling》2008,23(3-4):82-101

The variability in the Caribbean Sea is investigated using high resolution (1/15°) general circulation model experiments. For the first time in this region, simulations were carried out with a 2-way nested configuration of the NEMO primitive equation model. A coarse North Atlantic grid (1/3°) reproduces the main features of the North Atlantic and Equatorial circulation capable of influencing ocean dynamics in the Caribbean Sea. This numerical study highlights strong dynamical differences among basins and modifies the view that dynamics are homogeneous over the whole Caribbean Basin. The Caribbean mean flow is shown to organize in two intense jets flowing westward along the northern and southern boundaries of the Venezuela Basin, which merge in the center of the Colombia Basin. Diagnostics of model outputs show that width, depth and strength of baroclinic eddies increase westward from the Lesser Antilles to the Colombia Basin. The widening and strengthening to the west is consistent with altimetry data and drifter observations. Although influenced by the circulation in the Colombia Basin, the variability in the Cayman Basin (which also presents a westward growth from the Chibcha Channel) is deeper and less energetic than the variability in the Colombia/Venezuela Basins. Main frequency peaks for the mesoscale variability present a westward shift, from roughly 50 days near the Lesser Antilles to 100 days in the Cayman Basin, which is associated with growth and merging of eddies.  相似文献   

Prototype measurements and small-scale model tests of wave overtopping at shallow rubble-mound breakwaters: the Ostia-Rome yacht harbour case     

Leopoldo Franco  Jimmy Geeraerts  Riccardo Briganti  Marc Willems  Giorgio Bellotti  Julien De Rouck 《Coastal Engineering》2009

The paper presents the comparison between the results of small-scale model tests and prototype measurements of wave overtopping at a rubble-mound breakwater. The specific structure investigated is the west breakwater of the yacht harbour of Rome at Ostia (Italy) and is characterized by a gentle seaward slope (1/4) and by a long, shallow foreshore. The laboratory tests firstly aimed at carefully reproducing two measured storms in which overtopping occurred and was measured. The tests have been carried out in two independent laboratories, in a wave flume and in a wave basin, hence using a two-dimensional (2-D) and a three-dimensional (3-D) setup. In the 2-D laboratory tests no overtopping occurred during the storm reproductions; in the 3-D case discharges five to ten times smaller than those observed in prototype have been measured. This indicates the existence of model and scale effects. These effects have been discussed on the basis of the results of several parametric tests, which have been carried out in both laboratories, in addition to the storm reproductions, varying wave and water level characteristics. Final comparison of all the performed tests with 86 prototype measurements still suggests the existence of scale and model effects that induce strong underestimation of overtopping discharge at small scale. The scale reproduction of wave breaking on the foreshore, together with the 3-D features of the prototype conditions and the absence of wind stress in the laboratory measurements, have been individuated as the main sources of scale and model effects. The paper also provides a comparison between the data and a largely used formula for wave overtopping discharges in the presence of structures similar to the one at hand. The suitable value of a roughness factor that appears in that formula is investigated and good agreement is found with other recent researches on rubble-mound breakwaters.  相似文献   

Late Miocene to Quaternary slip history across the Qiulitag anticline in the southern Tianshan piedmont     

Julien Charreau  Amandine Sartgou  Dimitri Saint‐Carlier  Jrme Lav  Pierre‐Henri Blard  Stphane Dominguez  Sheng Li Wang  Gang Rao 《地学学报》2020,32(1):89-96

In this study, we reconstruct the Miocene to Quaternary shortening history across the Qiulitag anticline, a complex fault‐bend fold located in southern Tianshan. We studied the Yaha and Kuche sections, where we combined surface structural measurements and seismic imaging to model the stratigraphic horizons. The history of folding was reconstructed based on magnetostratigraphic analyses and eight cosmogenic burial ages in Kuche. Pleistocene deformation rates were also quantified in Yaha based on a deformed fluvial terrace that we dated to ~67 ka using a cosmogenic depth profile. Our results suggest that the fold grew at a mean slip rate of 0.9–1.3 mm/a in both sections but accelerated to ~2.5 mm/a during the Pleistocene in Kuche. These results support a migration of the deformation towards the basin during the Pleistocene and suggest that most of the present deformation in the Tianshan is accommodated across the external structures of the range.  相似文献   

Earth system curator: metadata infrastructure for climate modeling     

Rocky Dunlap  Leo Mark  Spencer Rugaber  V. Balaji  Julien Chastang  Luca Cinquini  Cecelia DeLuca  Don Middleton  Sylvia Murphy 《Earth Science Informatics》2008,1(3-4):131-149

The Earth System Curator is a National Science Foundation sponsored project developing a metadata formalism for describing the digital resources used in climate simulations. The primary motivating observation of the project is that a simulation/model’s source code plus the configuration parameters required for a model run are a compact representation of the dataset generated when the model is executed. The end goal of the project is a convergence of models and data where both resources are accessed uniformly from a single registry. In this paper we review the current metadata landscape of the climate modeling community, present our work on developing a metadata formalism for describing climate models, and reflect on technical challenges we have faced that require new research in the area of Earth Science Informatics.  相似文献   

Petroleum and aqueous inclusions from deeply buried reservoirs: Experimental simulations and consequences for overpressure estimates   总被引：1，自引：0，他引：1  

Jacques Pironon  Julien Bourdet 《Geochimica et cosmochimica acta》2008,72(20):4916-4928

Synthetic hydrocarbon and aqueous inclusions have been created in the laboratory batch reactors in order to mimic inclusion formation or re-equilibration in deeply buried reservoirs. Inclusions were synthesized in quartz and calcite using pure water and Mexican dead oil, or n-tetradecane (C₁₄H₃₀), at a temperature and pressure of 150 °C and 1 kbar. One-phase hydrocarbon inclusions are frequently observed at standard laboratory conditions leading to homogenization temperatures between 0 and 60 °C. UV epifluorescence of Mexican oil inclusions is not uniform; blue and green-yellow colored inclusions coexist; however, no clear evidence of variations in fluid chemistry were observed. Homogenization temperatures were recorded and the maxima of T_h plotted on histograms are in good agreement with expected T_h in a range of 6 °C. Broad histograms were reconstructed showing non-symmetrical T_h distributions over a 20 °C temperature range centered on the expected T_h. This histogram broadening is due to the fragility of the fluid inclusions that were created by re-filling of pre-existing microcavities. Such T_h histograms are similar to T_h histograms recorded on natural samples from deeply buried carbonate reservoirs. T_h values lower than those expected were measured for hydrocarbon inclusions in quartz and calcite, and for aqueous inclusions in calcite. However, the results confirm the ability of fluid inclusions containing two immiscible fluids to lead to PT reconstructions, even in overpressured environments.  相似文献