Analysis and modeling of the seasonal South China Sea temperature cycle using remote sensing   总被引：1，自引：0，他引：1  

Daniel J. Twigt  Erik D. De Goede  Ernst J. O. Schrama  Herman Gerritsen 《Ocean Dynamics》2007,57(4-5):467-484

The present paper describes the analysis and modeling of the South China Sea (SCS) temperature cycle on a seasonal scale. It investigates the possibility to model this cycle in a consistent way while not taking into account tidal forcing and associated tidal mixing and exchange. This is motivated by the possibility to significantly increase the model’s computational efficiency when neglecting tides. The goal is to develop a flexible and efficient tool for seasonal scenario analysis and to generate transport boundary forcing for local models. Given the significant spatial extent of the SCS basin and the focus on seasonal time scales, synoptic remote sensing is an ideal tool in this analysis. Remote sensing is used to assess the seasonal temperature cycle to identify the relevant driving forces and is a valuable source of input data for modeling. Model simulations are performed using a three-dimensional baroclinic-reduced depth model, driven by monthly mean sea surface anomaly boundary forcing, monthly mean lateral temperature, and salinity forcing obtained from the World Ocean Atlas 2001 climatology, six hourly meteorological forcing from the European Center for Medium range Weather Forecasting ERA-40 dataset, and remotely sensed sea surface temperature (SST) data. A sensitivity analysis of model forcing and coefficients is performed. The model results are quantitatively assessed against climatological temperature profiles using a goodness-of-fit norm. In the deep regions, the model results are in good agreement with this validation data. In the shallow regions, discrepancies are found. To improve the agreement there, we apply a SST nudging method at the free water surface. This considerably improves the model’s vertical temperature representation in the shallow regions. Based on the model validation against climatological in situ and SST data, we conclude that the seasonal temperature cycle for the deep SCS basin can be represented to a good degree. For shallow regions, the absence of tidal mixing and exchange has a clear impact on the model’s temperature representation. This effect on the large-scale temperature cycle can be compensated to a good degree by SST nudging for diagnostic applications.  相似文献   

Long-term effects of anthropogenic CO<Subscript>2</Subscript> emissions simulated with a complex earth system model     

Uwe Mikolajewicz  Matthias Gröger  Ernst Maier-Reimer  Guy Schurgers  Miren Vizcaíno  Arne M. E. Winguth 《Climate Dynamics》2007,28(6):599-633

A new complex earth system model consisting of an atmospheric general circulation model, an ocean general circulation model, a three-dimensional ice sheet model, a marine biogeochemistry model, and a dynamic vegetation model was used to study the long-term response to anthropogenic carbon emissions. The prescribed emissions follow estimates of past emissions for the period 1751–2000 and standard IPCC emission scenarios up to the year 2100. After 2100, an exponential decrease of the emissions was assumed. For each of the scenarios, a small ensemble of simulations was carried out. The North Atlantic overturning collapsed in the high emission scenario (A2) simulations. In the low emission scenario (B1), only a temporary weakening of the deep water formation in the North Atlantic is predicted. The moderate emission scenario (A1B) brings the system close to its bifurcation point, with three out of five runs leading to a collapsed North Atlantic overturning circulation. The atmospheric moisture transport predominantly contributes to the collapse of the deep water formation. In the simulations with collapsed deep water formation in the North Atlantic a substantial cooling over parts of the North Atlantic is simulated. Anthropogenic climate change substantially reduces the ability of land and ocean to sequester anthropogenic carbon. The simulated effect of a collapse of the deep water formation in the North Atlantic on the atmospheric CO₂ concentration turned out to be relatively small. The volume of the Greenland ice sheet is reduced, but its contribution to global mean sea level is almost counterbalanced by the growth of the Antarctic ice sheet due to enhanced snowfall. The modifications of the high latitude freshwater input due to the simulated changes in mass balance of the ice sheet are one order of magnitude smaller than the changes due to atmospheric moisture transport. After the year 3000, the global mean surface temperature is predicted to be almost constant due to the compensating effects of decreasing atmospheric CO₂ concentrations due to oceanic uptake and delayed response to increasing atmospheric CO₂ concentrations before.  相似文献   

Evolution of metamorphic volatiles during exhumation of microdiamond-bearing granulites in the Western Gneiss Region, Norway   总被引：1，自引：0，他引：1  

Rune B. Larsen  Elizabeth A. Eide  Ernst A. J. Burke 《Contributions to Mineralogy and Petrology》1998,133(1-2):106-121

Fluid inclusions in garnet, kyanite and quartz from microdiamond-bearing granulites in the Western Gneiss Region, Norway, document a conspicuous fluid evolution as the rocks were exhumed following Caledonian high- and ultrahigh-pressure (HP–UHP) metamorphism. The most important of the various fluid mixtures and daughter minerals in these rocks are: (N₂ + CO₂ + magnesian calcite), (N₂ + CO₂ + CH₄ + graphite + magnesian calcite), (N₂ + CH₄), (N₂ + CH₄ + H₂O), (CO₂) and (H₂O + NaCl + CaCl₂ + nahcolite). Rutile also occurs in the N₂ + CO₂ inclusions as a product of titanium diffusion from the garnet host into the fluid inclusions. Volatiles composed of N₂ + CO₂ + magnesian calcite characterise the ambient metamorphic environment between HP–UHP (peak) and early retrograde metamorphism. During progressive decompression, the mole fraction of N₂ increased in the fluid mixtures; as amphibolite-facies conditions were reached, CH₄ and later, H₂O, appeared in the fluids, concomitant with the disappearance of CO₂ and magnesian calcite. Graphite is ubiquitous in the host lithologies and fluid inclusions. Thermodynamic modelling of the metamorphic volatiles in a graphite-buffered C-O-H system demonstrates that the observed metamorphic volatile evolution was attainable only if the f _O2 increased from c. −3.5 (±0.3) to −0.8 (±0.3) log units relative to the FMQ oxygen buffer. External introduction of oxidising aqueous solutions along a system of interconnected ductile shear zones adequately explains the dramatic increase in the f _O2. The oxidising fluids introduced during exhumation were likely derived from dehydration of oceanic crust and continental sediments previously subducted during an extended period of continental collision in conjunction with the Caledonian orogeny. Received: 15 December 1997 / Accepted: 25 May 1998  相似文献   

A general mixing equation with applications to Icelandic basalts   总被引：4，自引：0，他引：4  

Charles H. Langmuir  Robert D. Vocke  Gilbert N. Hanson  Stanley R. Hart 《Earth and Planetary Science Letters》1978,37(3):380-392

The mixing equation applied by Vollmer [1] to Pb and Sr isotope ratios is shown to be a general equation applicable to consideration of element and isotope ratios. The mixing equation is hyperbolic and has the form:Ax + Bxy + Cy + D = 0where the coefficients are dependent on the type of plot considered: i.e. ratio-ratio, ratio-element, or element-element. Careful use of this equation permits testing whether mixing is a viable process, places constraints on end member compositions, allows distinction between mixing of sources and mixing of magmas, and should allow distinction between recent mixing and long-term evolution of sources.The available chemical data for postglacial basalts from Iceland and along the Reykjanes Ridge are not consistent with either mixing of magmas or simple mixing of an enriched ocean island source with a depleted ocean ridge source. If the available analyses for basalts are representative of the source regions, the data are consistent with at least two models neither of which can be properly tested with the available data.(1) There are two separate mixing trends: one beneath Iceland with the alkali basalt source and a depleted Iceland source as end members; the second along the Reykjanes Ridge with a heterogeneous ocean ridge basalt source and a source similar to that for intermediate basalts on Iceland as end members. The depleted Iceland source and the depleted ocean ridge source are not the same.(2) The chemistry of the basalts is not determined by mixing. Instead the basalts are derived from a multiplicity of sources with a similar history which have been isolated for hundreds of millions of years.  相似文献   

Modelling of major elements in mantle-melt systems using trace element approaches   总被引：1，自引：0，他引：1  

Gilbert N. Hanson  Charles H. Langmuir 《Geochimica et cosmochimica acta》1978,42(6):725-741

Major elements can be modelled in ways similar to the quantitative petrogenetic modelling used for trace elements. In contrast to modelling with trace elements, however, modelling with major elements is constrained by the stoichiometry of the solid phases. Within these constraints, the same equations for partial melting and crystallization which have been used to such advantage for trace elements may be used for major elements.Calculated MgO and FeO abundances in a mantle-melt system are used as an example of the modelling technique. Such modelling yields limited fields of permissible melts and residues for a given parent composition, but does not give the paths of melting. It does allow the temperature and extent of melting which gave rise to a melt to be determined from the MgO and FeO abundances of the melt or residual solid. Applying the results of the modelling to igneous rocks and ultramafic nodules leads to the following conclusions, which are subject to the uncertainties in the available distribution coefficients. Least differentiated basalt glasses from the ocean floor are derived from parent melts with less than 15.5 weight % MgO and 8.2 wt. % FeO. Komatiites may be derived by less than 60% melting of a pyrolite source leaving a residue of olivine and pyroxene. Many nodules from the subcontinental mantle appear to be residues of large fractions of melting (>30%) at high temperature and pressure, whereas ultramafic nodules from oceanic basalts appear to be residues of smaller fractions of melting (<30%) at lower temperatures and pressures.  相似文献   

Particulate dispersion from sources within a forest     

Gilbert S. Raynor  Janet V. Hayes  Eugene C. Ogden 《Boundary-Layer Meteorology》1975,9(3):257-277

Particulate dispersion from sources within a 10- to 13-m tall pine forest was studied experimentally at Brookhaven National Laboratory using stained ragweed pollen and other tracers ranging from 14 to 58 m in size. Forty-seven continuous point source releases lasting from 22 to 55 min were made at heights from 1.75 to 14.0 m from locations having a long fetch through the forest. In most experiments, differently colored ragweed pollen were emitted simultaneously from three locations. In other tests, several particle types were released from a single point. The sampling network consisted of 119 rotoslide samplers at heights from 0.5 to 21.0 m at 57 positions within and at the edge of the forest. Deposition to the ground was sampled by greased microscope slides at each position. Meteorological measurements were taken in and near the forest.Data were classified by particle characteristics, source height and meteorological parameters. Concentration patterns were illustrated on scale diagrams of the sampling grid. Changes in centerline and crosswind integrated concentrations, plume width and height, mass flux, deposition and deposition velocity were studied as a function of distance, particle size and wind speed. Results were compared to those obtained from similar releases over open terrain.In the forest, vertical predominates over lateral dispersion and considerable interchange occurs through the canopy. Flow is channelled somewhat by vegetation density differences but is generally in the direction of the mean wind above the forest. No systematic turning of the wind with height was observed. Most particles are lost to the foliage rather than to the ground and large particles are lost more rapidly than smaller ones. Rate of change in mass flux is similar to that over open terrain and is greater with light than with stronger wind speeds.This research was carried out under the auspices of the New York State Museum and Science Service and the U.S. Atomic Energy Commission (now Energy Research and Development Administration) and was partially supported by Research Grant No. R-800677 from the Division of Meteorology, U.S. Environmental Protection Agency.  相似文献   

Some effects of the Atlantic circulation and of river discharges on the residual circulation of the North Sea     

Dr. Ernst Maier-Reimer 《Ocean Dynamics》1979,32(3):126-130

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Cyclic triaxial tests on frozen sand     

John C. Li  Gilbert Y. Baladi  O.B. Andersland 《Engineering Geology》1979,13(1-4):233-246

Strain-controlled cyclic triaxial tests were performed on a one-size silica (Ottawa) sand artificially frozen into 71.1-mm-diameter cylindrical samples. Ice-saturated samples with three different sand contents were tested under the following conditions: axial strains ranging from 3 × 10⁻³ to 3 X 10⁻²%, confining pressures from zero to 1.378 MPa, frequencies of 0.05–5.0 cps and temperatures from −1 to −10 °C.

Test equipment included (1) an MTS electrohydraulic closed-loop testing system which applies the load to the sample, (2) a triaxial cell completely immersed in a low-temperature coolant for temperature control, (3) a refrigeration unit for control of the coolant temperature and constant coolant circulation and (4) measuring devices including an LVDT and load cell, together with recording devices such as a digital multimeter, an oscilloscope, a strip-chart recorder and a minicomputer.

Test results indicate that the dynamic Young's modulus increases with increasing frequency, confining pressure and sand content, but decreases with increasing strain and temperature. The damping ratio decreases with increasing frequency, sand content and lower temperatures. The influence of confining pressures and axial strain on the damping ratio are less explicit for the ranges considered. The experimental results are compared with data from other sources.  相似文献   

The Equatorial Glaciers of New Guinea—Results of the 1971–1973 Australian Universities' Expeditions to Irian Jaya: Survey, glaciology, meteorology, biology and palaeoenvironments : Edited by G. S. Hope, J. A. Peterson, U. Radok, and I. Allison. A. A. Balkema, Rotterdam, 1976, 244 pp. $14.80     

Ernst Lffler 《Quaternary Research》1979,11(3):388-389

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Geologic evolution of the westernmost part of the internal Betic zone (Betic Cordilleras,Southern Spain)     

Dr. Theodor Ernst Felder 《International Journal of Earth Sciences》1980,69(1):131-148

The Serranía de Ronda (western Betic Cordilleras, S-Spain) is formed by different tectonic units of the Betic internal domain. Stratigraphic correlations of the Permo-Triassic and Triassic sedimentary sequences imply that one part of the Mesozoic carbonates of the Rondaides (Dorsale bétique), namely the Cabrilla unit (Dorsale interne), is shearedoff from the frontal part of the Malaguides, and another part (Nieves unit, Dorsale externe) forms the Mesozoic cover of the alpujarride Casares unit. The first alpine compressional phases took place in the Paleogene; post-metamorphic movements followed in the time between the Upper Aquitanian and the Upper Tortonian. From geometrical considerations it can be concluded that the Malaguides originated paleogeographically from a more internal region than the Alpujarrides.

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Zusammenfassung Am Aufbau der Serranía de Ronda (westliche Betische Kordilleren, S-Spanien) nehmen verschiedene Einheiten der betischen Intemzonen teil. Stratigraphische Vergleiche der permotriadischen und triadischen Sedimentserien erlauben den Schluß, daß die mesozoischen Karbonate der Rondaiden (Dorsale bétique) zu einem Teil (Cabrilla-Einheit, Dorsale interne) von der frontalen Partie der Malagiden abglitten und zum anderen Teil (Nieves-Einheit, Dorsale externe) das abgescherte Mesozoikum der alpujarriden Casares-Einheit bilden. Die ersten alpinen Kompressionsphasen sind im Paleogen anzusetzen, da für mesozoische Deckenbewegungen beweiskräftige Argumente fehlen. Zwischen Oberaquitanian und Obertortonian fanden post-metamorphe Überschiebungen statt. Aus geometrischen Gründen wird angenommen, daß die Malagiden paläogeographisch internerer Herkunft sein müssen als die benachbarten Alpujarriden.

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Resumen La Serranía de Ronda (Cordilleras béticas occidentales, Prov. Málaga) está formado por diferentes unidades del conjunto bético interno. Correlaciones estratigráficas del Permo-Triásico y del Triásico de los diferentes unidades permiten la conclusión que los Rondáides (Dorsal bética) está por una parte (unidad de Cabrilla, Dorsal interna) el revestimiento mesozóico de la parte frontal de los mantos maláguides, y por otra parte (unidad de las Nievas, Dorsal externa) la parte mesozóica de la unidad alpujárride de Casares. Las primeras fases alpinas de compresión deben ser situadas en el Paleógeno. Las traslaciones post-metamórficas de mantos son de edad aquitaniense superior hasta pre-tortoniense superior. Con argumentación geométrica se puede concluir que los Maláguides son de un orígen paleográfico más interno que los Alpujárrides.

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