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1.
Ultrasonic longitudinal acoustic velocities in oxidized silicate liquids indicate that the pressure derivative of the partial-molar volume of Fe2O3 is the same in iron-rich alkali-, alkaline earth- and natural silicate melt compositions at 1 bar. The dV/dP for multicomponent silicate liquids can be expressed as a linear combination of partial-molar constants plus a positive excess term for Na2O−Al2O3 mixing. Partial-molar properties for FeO and Fe2O3 components allow extension of the empirical expression of Sack et al. (1980) to permit the calculation of Fe-redox equilibrium in a natural silicate liquid as a function of composition, temperature, fo2 and pressure; a more formal thermodynamic expression is presented in the Appendix. The predicted equilibrium fo2 of natural silicate melts, of fixed oxygen content, closely parallels that defined by the metastable assemblage fayalite+magnetite+β-quartz (FMQ), in pressure-temperature space. A silicate melt initially equilibrated at 3 GPa and FMQ, will remain within approximately 0.5 log10 units of FMQ during its closed-system ascent. Thus, for magmas closed to oxygen, iron-redox equilibrium in crystal-poor pristine glassy lavas represents an excellent probe of the relative oxidation state of their source regions.  相似文献   
2.
Snodgrass  H.B.  Kress  J.M.  Wilson  P.R. 《Solar physics》2000,191(1):1-19
The Mount Wilson synoptic magnetic data for the period September 1987 through March 1996 are completely revised and used to provide polar plots of the solar magnetic fields for both hemispheres. This period, from Carrington rotations 1793 to 1906, covers the reversals of the polar magnetic fields in cycle 22. Comparison of our plots with the presently available H filtergrams for this period shows that the polarity boundaries are consistent in these two data sets where they overlap. The Mount Wilson plots show that the polar field reversals involve a complex sequence of events. Although the details differ slightly, the basic patterns are similar in each hemisphere. First the old polarity becomes isolated at the pole, then shortly thereafter, the isolation is broken, and the polar field includes unipolar regions of both polarities. The old polarity then reclaims the polar region, but when the isolation of this field is established for a second time, it declines in both area and strength. We take the reversal to be complete when the old polarity field is no longer observed in the Mount Wilson plots. With this criterion we find that the polar field reversal is completed in the north by CR 1836, i.e., by December 1990, and in the south by CR 1853, i.e., March 1992.  相似文献   
3.
4.
The objective of this study was to examine whether dissolved inorganic phosphate (DIP) is removed from the Eastern Mediterranean Sea by adhering to atmospherically deposited loess particles sinking through the water column. In a series of radiolable experiments, loess from the Negev Desert, treated in various ways, was added to surface (SSW) and deep (DSW) seawater spiked with 32PO4−3. It was shown that when fresh loess reaches the Mediterranean SSW approximately 1.3 μmol P/g are released (11% of the total P concentration). Biological activity and inorganic particles removed similar amounts of the tracer (30–40%) from SSW. It was estimated that about 0.2 μmol P/g of ‘aged loess' (proxy of particles sinking into DSW), were removed from poisoned SSW and DSW, while there was minor adsorption when either nothing or quartz powder was added. The adsorbed DIP accounts for approximately 15% of the released P and is equivalent to about 2% of the remaining P (11.17 μmol P/g loess). Therefore, the process of DIP removal by atmospherically derived particles exists, but due to the higher release of P, the result is a net addition of dissolved atmospheric phosphorus in seawater. It is postulated that in actual SSW where dust concentrations are much lower, biological uptake out-competes inorganic adsorption, although it was demonstrated that the decrease in loess particle concentrations tends to increase their adsorption capacity. As the loess descends into the DSW it continues to remove DIP and thus transports phosphate from the water column to the sediments. A preliminary quantitative estimate suggests that the process of DIP removal by loess particles cannot explain the phosphate ‘deficit' in the Eastern Mediterranean DSW characterized by unusually high DIN/DIP ratios (27) reported by others.  相似文献   
5.
Zusammenfassung Aus der 300mb-Fläche der täglichen Wetterkarte des deutschen Wetterdienstes wurden für den Zeitraum von 1955 bis 1963 Lage, Richtung und Geschwindigkeit der hochtroposphärischen Strahlströme bestimmt. Die jahreszeitlichen Änderungen der Positionen, Intensitäten und Richtungen des Polarfront-Jet (PFJ) und des Subtropen-Jet (STJ) werden für den Bereich von 20° W bis 20° E und von 35° N bis 70° N angegeben und diskutiert.
Summary The position, direction and speed of the high-tropospheric jet-streams in the years 1955 to 1963 were determined from the 300 mb chart of the Daily Weather Map of the German Weather Service. The seasonal variations of the positions, intensities and directions of the polarfront jet (PFJ) and subtropic jet (STJ) in the region between 20° W and 20° E and between 35° N and 70° N have been evaluated and are discussed here.

Résumé En partant des cartes journalières de la surface de 300 mb éditées par le service météorologique de la République fédérale d'Allemagne, on a déterminé la position, la direction et la vitesse des courants jets de la troposphère supérieure et cela pour la période 1955 à 1963. On indique et on discute les variations saisonnières de la position, de l'intensité et de la direction du jet accompagnant le front polaire (PFJ) et du Jet subtropical (STJ). La zone étudiée s'étend entre le 20ème méridien E et le 20ème méridien W, respectivement entre les 35ème et 70ème paralèlles N.


Mit 6 Textabbildungen  相似文献   
6.
Summary Since early experiments by Renard and Clarke in 1965 there has been until now no essential progress in numerical frontal analysis. To overcome the frequent lack of agreement of frontal analysis between different analysts and weather bureau centers an objective frontal analysis model seems to be necessary. Therefore an attempt will be made to develop an algorithm to analyse fronts in relation to their location, type and activity by a numerical method.With 12 Fugures  相似文献   
7.
We present a new formulation to describe the thermodynamics of liquids in the system O-S-Fe. The model is based on an associated regular solution formulation. According to this model, liquids in the O-S-Fe ternary are made up of an equilibrium solution of the six melt species S, Fe, FeO, FeO1.5, FeS and FeOS. The model presented here represents oxygen and sulfur fugacities as well as phase equilibria with stoichiometric solid phases better than models from the literature on O-Fe and S-Fe binaries. Furthermore, this model represents a substantial improvement on the model of Kress (1997), which is the only other thermodynamic model available in the ternary system. Asymmetric regular solution parameters are required along the FeO join in order to reproduce experimental data with the chosen list of species. Symmetric regular solution parameters are required along the Fe-S binary. Mixing between any of the species considered and FeOS close to ideal. The associated solution model presented here will serve as a more solid foundation for future models in O-S-Fe- Ni-Cu liquids. Efficient and robust strategies for calculating equilibrium speciation and estimating model parameters are presented. Received: 15 June 1999 / Accepted: 5 February 2000  相似文献   
8.
This paper describes an innovative method to characterise conduction parameters in geomaterials at the particle-scale. The technique is exemplified using 3D synthetic grain packing generated with discrete element approaches. This creates a geo-mechanically viable user-defined 3D granular image through which the particle skeleton and the corresponding pore network are constructed. Images are then imported into the finite element analyses to solve the governing equations of hydraulic and thermal conduction. Navier–Stokes equation is uniquely upscaled to Darcy’s law to assess hydraulic conductivity in soils, while a similar approach implements the Fourier equation to evaluate thermal conduction through grain chains and pore network. High performance computing is used to meet demanding numerical calculations of 3D meshed geometries. Packing density (i.e., porosity) and inter-particle contact areas are explored as variables to highlight the effects of pore volume and inter-particle contact condition in hydraulic and thermal conduction. This emerging technique allows not only characterising the macro-scale behaviour of conduction phenomena in soils but also quantifying and visualising the preferential and local conduction behaviour at the particle-scale. Laboratory measurements of hydraulic and thermal conductivities support numerically obtained results and validate the viability of the new methods used herein. This study introduces an alternative way to determine physical parameters of soils using emerging technology of rigorous numerical simulations in conjunction with 3D images, and to enable fundamental observation of particle-scale mechanisms of macro-scale manifestation.  相似文献   
9.
We have studied the evolution of several high-latitude flux `plumes', i.e., unipolar regions, trailing from active regions which emerged near sunspot maximum in cycle 23. The observed patterns are compared with simulations using a simple flux transport equation based on the observed flux for an earlier Carrington rotation. In addition to the long recognized poleward migration and diffusion of flux from active regions, it is found that the evolution of the trailing plumes may be influenced by flux which emerges above latitude 35° over areas of all scales. We describe two cases in which the emerging flux appears in the form of bipolar flux patterns which are not obviously related to sunspots. Further, we find instances in which the observed surface flux decreases or spreads at rates which cannot be explained solely in terms of diffusion using the normally accepted rates. Thus in several cases the poleward migration of flux cannot be described in terms of passive transport by advection and diffusion as considered here, and further investigation of the processes that contribute to the evolution of the polar fields is required.  相似文献   
10.
In this paper we present the concentrations of Hg, Cd, Se, Pb, Cu, Mn, Zn and Fe in organs of 6 non-common specimens of cetaceans that were stranded along the Israeli Mediterranean coast (IMC), during 2002–2010: two fin whales, one minke whale, one Cuvier’s beaked whale, one rough-toothed dolphin, and one Risso’s dolphin. Most of the specimens were calves stranded by accident. Concentrations of Hg and Cd were low in tissues of the baleen whales and higher in the toothed whales, with maximum concentrations of 1067 mg kg−1 Hg in the liver of the Risso’s dolphin and 29 mg kg−1 Cd in the kidney of the Cuvier’s beaked whale. As far as we are aware, this is the first report of trace elements in baleen whales in the Eastern Mediterranean, and the first report of trace elements in minke whale and rough-toothed dolphin in the Mediterranean.  相似文献   
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