Determination of the Concentration of Carbonic Species in Natural Waters: Results from a World‐Wide Proficiency Test          下载免费PDF全文

Mahendra P. Verma  Enrique Portugal  Sophie Gangloff  María Aurora Armienta  Dornadula Chandrasekharam  Mayela Sanchez  Roberto E. Renderos  Miguel Juanco  Robert van Geldern 《Geostandards and Geoanalytical Research》2015,39(2):233-255

The results of an international interlaboratory proficiency test for the determination of carbonic species are presented. Eight laboratories analysed twelve water samples (four synthetic waters, one lake water, four geothermal waters, one seawater and two petroleum waters) by two methods: (a) individual laboratory analytical procedure and (b) acid–base titration curves in tabular form following a standardised protocol. In case (b), the concentrations of carbonic species were calculated by the organiser using the (1) Hydrologists' method, (2) Geochemists' method and/or (3) initial pH and total alkalinity method. For synthetic waters, the averaged % trueness and precision of measurement of the two methods were (trueness = 7.6, precision = 9.4) and (9.0, 3.4) for total alkalinity, and (6.6, 31.0) and (7.8, 6.1) for carbonic alkalinity, respectively. This indicates that the total alkalinity calculation procedure is in general correct in the individual laboratory method, but the carbonic alkalinity calculation procedure has serious problems. The measurements of total alkalinity for lake and seawaters were in agreement in both the methods; however, the individual laboratory measurement method for geothermal and petroleum waters was conceptually incorrect. Thus, the analytical procedures for the determination of carbonic species were reviewed. To apply the Hydrologists' and/or Geochemists' methods, the location of NaHCO₃EP and H₂CO₃EP is necessary, even for samples with pH lower than that of NaHCO₃EP, and a backward titration curve after complete removal of CO₂ must be performed. The initial pH and total alkalinity method is appropriate where a complete analysis of species that contribute to the alkalinity is known.  相似文献   

LavAtmos: An open-source chemical equilibrium vaporization code for lava worlds     

Christiaan P. A. van Buchem  Yamila Miguel  Mantas Zilinskas  Wim van Westrenen 《Meteoritics & planetary science》2023,58(8):1149-1161

To date, over 500 short-period rocky planets with equilibrium temperatures above 1500 K have been discovered. Such planets are expected to support magma oceans, providing a direct interface between the interior and the atmosphere. This provides a unique opportunity to gain insight into their interior compositions through atmospheric observations. A key process in doing such work is the vapor outgassing from the lava surface. LavAtmos is an open-source code that calculates the equilibrium chemical composition of vapor above a dry melt for a given composition and temperature. Results show that the produced output is in good agreement with the partial pressures obtained from experimental laboratory data as well as with other similar codes from literature. LavAtmos allows for the modeling of vaporization of a wide range of different mantle compositions of hot rocky exoplanets. In combination with atmospheric chemistry codes, this enables the characterization of interior compositions through atmospheric signatures.  相似文献   

Nesting Turbulence in an Offshore Convective Boundary Layer Using Large-Eddy Simulations   总被引：1，自引：1，他引：0  

Domingo Muñoz-Esparza  Branko Kosović  Clara García-Sánchez  Jeroen van Beeck 《Boundary-Layer Meteorology》2014,151(3):453-478

The applicability of the one-way nesting technique for numerical simulations of the heterogeneous atmospheric boundary layer using the large-eddy simulation (LES) framework of the Weather Research and Forecasting model is investigated. The focus of this study is on LES of offshore convective boundary layers. Simulations were carried out using two subgrid-scale models (linear and non-linear) with two different closures [diagnostic and prognostic subgrid-scale turbulent kinetic energy (TKE) equations]. We found that the non-linear backscatter and anisotropy model with a prognostic subgrid-scale TKE equation is capable of providing similar results when performing one-way nested LES to a stand-alone domain having the same grid resolution but using periodic lateral boundary conditions. A good agreement is obtained in terms of velocity shear and turbulent fluxes, while velocity variances are overestimated. A streamwise fetch of 14 km is needed following each domain transition in order for the solution to reach quasi-stationary results and for the velocity spectra to generate proper energy content at high wavelengths, however, a pile-up of energy is observed at the low-wavelength portion of the spectrum on the first nested domain. The inclusion of a second nest with higher resolution allows the solution to reach effective grid spacing well within the Kolmogorov inertial subrange of turbulence and develop an appropriate energy cascade that eliminates most of the pile-up of energy at low wavelengths. Consequently, the overestimation of velocity variances is substantially reduced and a considerably better agreement with respect to the stand-alone domain results is achieved.  相似文献   

Bridging the Transition from Mesoscale to Microscale Turbulence in Numerical Weather Prediction Models   总被引：1，自引：1，他引：0  

Domingo Muñoz-Esparza  Branko Kosović  Jeff Mirocha  Jeroen van Beeck 《Boundary-Layer Meteorology》2014,153(3):409-440

With a focus towards developing multiscale capabilities in numerical weather prediction models, the specific problem of the transition from the mesoscale to the microscale is investigated. For that purpose, idealized one-way nested mesoscale to large-eddy simulation (LES) experiments were carried out using the Weather Research and Forecasting model framework. It is demonstrated that switching from one-dimensional turbulent diffusion in the mesoscale model to three-dimensional LES mixing does not necessarily result in an instantaneous development of turbulence in the LES domain. On the contrary, very large fetches are needed for the natural transition to turbulence to occur. The computational burden imposed by these long fetches necessitates the development of methods to accelerate the generation of turbulence on a nested LES domain forced by a smooth mesoscale inflow. To that end, four new methods based upon finite amplitude perturbations of the potential temperature field along the LES inflow boundaries are developed, and investigated under convective conditions. Each method accelerated the development of turbulence within the LES domain, with two of the methods resulting in a rapid generation of production and inertial range energy content associated to microscales that is consistent with non-nested simulations using periodic boundary conditions. The cell perturbation approach, the simplest and most efficient of the best performing methods, was investigated further under neutral and stable conditions. Successful results were obtained in all the regimes, where satisfactory agreement of mean velocity, variances and turbulent fluxes, as well as velocity and temperature spectra, was achieved with reference non-nested simulations. In contrast, the non-perturbed LES solution exhibited important energy deficits associated to a delayed establishment of fully-developed turbulence. The cell perturbation method has negligible computational cost, significantly accelerates the generation of realistic turbulence, and requires minimal parameter tuning, with the necessary information relatable to mean inflow conditions provided by the mesoscale solution.  相似文献   

The role of technology for achieving climate policy objectives: overview of the EMF 27 study on global technology and climate policy strategies   总被引：3，自引：1，他引：2  

Elmar Kriegler  John P. Weyant  Geoffrey J. Blanford  Volker Krey  Leon Clarke  Jae Edmonds  Allen Fawcett  Gunnar Luderer  Keywan Riahi  Richard Richels  Steven K. Rose  Massimo Tavoni  Detlef P. van Vuuren 《Climatic change》2014,123(3-4):353-367

This article presents the synthesis of results from the Stanford Energy Modeling Forum Study 27, an inter-comparison of 18 energy-economy and integrated assessment models. The study investigated the importance of individual mitigation options such as energy intensity improvements, carbon capture and storage (CCS), nuclear power, solar and wind power and bioenergy for climate mitigation. Limiting the atmospheric greenhouse gas concentration to 450 or 550 ppm CO₂ equivalent by 2100 would require a decarbonization of the global energy system in the 21^st century. Robust characteristics of the energy transformation are increased energy intensity improvements and the electrification of energy end use coupled with a fast decarbonization of the electricity sector. Non-electric energy end use is hardest to decarbonize, particularly in the transport sector. Technology is a key element of climate mitigation. Versatile technologies such as CCS and bioenergy are found to be most important, due in part to their combined ability to produce negative emissions. The importance of individual low-carbon electricity technologies is more limited due to the many alternatives in the sector. The scale of the energy transformation is larger for the 450 ppm than for the 550 ppm CO₂e target. As a result, the achievability and the costs of the 450 ppm target are more sensitive to variations in technology availability.  相似文献   

Gorilla Tourism in Bwindi Impenetrable National Park,Uganda: An Actor-Network Perspective     

René van der Duim  Christine Ampumuza  Wilber Manyisa Ahebwa 《社会与自然资源》2014,27(6):588-601

This article performs actor-network theory (ANT) to examine the development of gorilla tourism at Bwindi Impenetrable National Park, Uganda. We depict a number of translations in which gorillas were designated and enrolled as coexisting with local livelihood practices, as “trophies” in the hunting network, “man's closest neighbor” in the scientific network, “endangered species” in the conservation network, and finally, through habituation processes, became part of the tourism network. These five versions of the “gorilla” network show how gorillas are shaped in and by the relations in which they reside. By examining Bwindi in terms of ANT's notions of ordering, materiality, and multiplicity, we not only show how gorilla tourism has gained permanence and popularity, but also draw attention to new ways of thinking about actors and agency in tourism, conservation, and development.  相似文献   

Impact of DEM source and resolution on topographic seismic amplification     

Muhammad Shafique  Mark van der Meijde  Norman Kerle  Freek van der Meer 《International Journal of Applied Earth Observation and Geoinformation》2011

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GPS-derived orbits for the GOCE satellite   总被引：5，自引：4，他引：1  

Heike Bock  Adrian Jäggi  Ulrich Meyer  Pieter Visser  Jose van den IJssel  Tom van Helleputte  Markus Heinze  Urs Hugentobler 《Journal of Geodesy》2011,85(11):807-818

The first ESA (European Space Agency) Earth explorer core mission GOCE (Gravity field and steady-state Ocean Circulation Explorer) was launched on 17 March 2009 into a sun-synchronous dusk–dawn orbit with an exceptionally low initial altitude of about 280 km. The onboard 12-channel dual-frequency GPS (Global Positioning System) receiver delivers 1 Hz data, which provides the basis for precise orbit determination (POD) for such a very low orbiting satellite. As part of the European GOCE Gravity Consortium the Astronomical Institute of the University of Bern and the Department of Earth Observation and Space Systems are responsible for the orbit determination of the GOCE satellite within the GOCE High-level Processing Facility. Both quick-look (rapid) and very precise orbit solutions are produced with typical latencies of 1 day and 2 weeks, respectively. This article summarizes the special characteristics of the GOCE GPS data, presents POD results for about 2 months of data, and shows that both latency and accuracy requirements are met. Satellite Laser Ranging validation shows that an accuracy of 4 and 7 cm is achieved for the reduced-dynamic and kinematic Rapid Science Orbit solutions, respectively. The validation of the reduced-dynamic and kinematic Precise Science Orbit solutions is at a level of about 2 cm.  相似文献   

Statistical characterization of composite protection levels for GPS   总被引：1，自引：1，他引：0  

Dean Bruckner  Frank van Graas  Trent Skidmore 《GPS Solutions》2011,15(3):263-273

A statistical characterization is presented of Global Positioning System (GPS) user range error as a normally distributed random variable with non-zero mean over the length of the aircraft precision approach operation, correlated from one GPS measurement epoch to another and from one satellite to another. This leads directly to modeling GPS error in the position domain as multivariate normal with non-zero mean. Based on this model, a vertical composite protection level VPL_c and a horizontal composite protection level HPL_c are each calculated as scalar values from a univariate normal distribution displaced from the origin by the worst-case position domain bias combination possible, given the maximum possible individual satellite bias magnitudes and the satellite geometry. A method is then presented by which exact values—that is, values accurate to a user-defined error tolerance and consistent with statistical assumptions—of VPL_c and HPL_c are obtained, and by which computationally efficient approximations may be evaluated. A statistical quadratic form under the multivariate normal distribution is used to derive a new class of protection levels based on the probability enclosed within a radius defined in two or more dimensions. A central Chi-square representation of this quadratic form is also presented and is incorporated into a six-step computational procedure for the two-dimensional composite radial protection level RPL_c. This procedure is extended to the spherical protection level (SPL_c) and the ellipsoidal protection level (EPL_c).  相似文献   

The representative concentration pathways: an overview   总被引：20，自引：4，他引：16  

Detlef P. van Vuuren  Jae Edmonds  Mikiko Kainuma  Keywan Riahi  Allison Thomson  Kathy Hibbard  George C. Hurtt  Tom Kram  Volker Krey  Jean-Francois Lamarque  Toshihiko Masui  Malte Meinshausen  Nebojsa Nakicenovic  Steven J. Smith  Steven K. Rose 《Climatic change》2011,109(1-2):5-31

This paper summarizes the development process and main characteristics of the Representative Concentration Pathways (RCPs), a set of four new pathways developed for the climate modeling community as a basis for long-term and near-term modeling experiments. The four RCPs together span the range of year 2100 radiative forcing values found in the open literature, i.e. from 2.6 to 8.5 W/m². The RCPs are the product of an innovative collaboration between integrated assessment modelers, climate modelers, terrestrial ecosystem modelers and emission inventory experts. The resulting product forms a comprehensive data set with high spatial and sectoral resolutions for the period extending to 2100. Land use and emissions of air pollutants and greenhouse gases are reported mostly at a 0.5?×?0.5 degree spatial resolution, with air pollutants also provided per sector (for well-mixed gases, a coarser resolution is used). The underlying integrated assessment model outputs for land use, atmospheric emissions and concentration data were harmonized across models and scenarios to ensure consistency with historical observations while preserving individual scenario trends. For most variables, the RCPs cover a wide range of the existing literature. The RCPs are supplemented with extensions (Extended Concentration Pathways, ECPs), which allow climate modeling experiments through the year 2300. The RCPs are an important development in climate research and provide a potential foundation for further research and assessment, including emissions mitigation and impact analysis.  相似文献