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841.
T. N. Krishnamurti John Molinari Hua-Lu Pan Vince Wong 《Pure and Applied Geophysics》1977,115(5-6):1357-1372
In this short paper we have identified some of the modelling groups that have the capability of simulating or carrying out short range numerical weather prediction over the monsoon belt. We have next outlined some of the important and desirable ingredients for a multilevel primitive equation model over the tropics, with most of the emphasis on the present version of Florida State University's Tropical Prediction Model. Finally, we present briefly some important results based on the present version of our prediction models that relate to the NWP efforts over the monsoon belt. Here we have identified the importance of mountains, convection, the radiative heating balance of the earth's surface, and the planetary boundary layer over the Arabian Sea. 相似文献
842.
A study of the historic record of activity of Piton de la Fournaise has revealed a cyclic pattern of eruption involving effusion of oceanite lava from major-flank centers every 20–40 years. Calculated volumes of the recent lava flows and pyroclastic ejecta have established an effusion rate of 3.9 m3 s−1 since 1931 and 6.2 m3 s−1 since 1951. Flank eruptions outside the present caldera define a distribution maximum which is expected to correlate with the depth range of a high-level magma reservoir.A model has been constructed which requires replenishment of a high-level magma chamber at a constant rate and regular eruption from summit and minor-flank centers, acting as “safety valves” to the magma chamber; when the magma chamber reaches its maximum expansion, a major-flank outburst of oceanitic lava occurs.The fact that calculated effusion rates are not consistent with radiometric dates implies an increase in effusion volume with time for the volcano. 相似文献
843.
844.
845.
846.
Vertical velocity profiles measured over various bed configurations (plane beds, ripples, and dunes) in. the meandering River South Esk, Glen Clova, Scotland are presented on semilogarithmic paper. Local bed shear stress and roughness height are calculated from the lowermost parts of the profiles using the Karman-Prandtl law of the wall; these parameters, and the geometrical properties of the profiles, are related to the various bed configurations. A graphical model is used to identify profiles developed on specific regions of dune geometry, in order to discriminate those profiles that define bed shear effective in transporting sediment over dunes. An assessment is made of the errors involved in estimating local mean velocity from extrapolating the law of the wall to the water surface. A Darcy-Weisbach friction coefficient is related to bed configuration and local stream power. 相似文献
847.
John T. Wasson 《Earth and Planetary Science Letters》1977,36(1):21-28
The high observed abundances of Na and Cu in chondrules indicate that the amount of loss during chondrule formation was minor and possibly negligible, consistent with the view that loss was controlled by diffusion kinetics rather than equilibrium volatility, and that the surface of the chondrule quickly cooled to temperatures at which diffusional transport was negligible. Ordinary chondrite/CI abundance ratios appear to be randomly distributed in the range 0.9-0.1. Very few values are observed in the 0.36–0.70 range, but this is not statistically significant, nor is it predicted by the two-component (chondrule-matrix) model.If CI chondrite abundances are representative of mean solar-system material, the very low chondrule content in CM chondrites (<5% of high-temperature materials) indicates that the observed volatile distribution resulted from incomplete accretion of volatile carriers (perhaps a fine aerosol). At the ordinary chondrite formation location the fraction of an element sited in unaccreted carriers increased with decreasing condensation temperature. At the CM location a similar trend is observed for elements less volatile than S, but the unaccreted fraction of more volatile elements was nearly constant. 相似文献
848.
Judith M. Capuzzo Joel C. Goldman John A. Davidson Sarah A. Lawrence 《Marine pollution bulletin》1977,8(7):161-163
The effects of free chlorine and chloramine on stage I lobster larvae and juvenile killifish were investigated in continuous flow bioassay units. In comparing mortality and changes in standard respiration rates during and after exposure to either chlorine form, significant respiratory stress was observed with exposure to sublethal levels. Sublethal responses to free and combined chlorine should be considered when establishing regulations for chlorine residuals in cooling waters. 相似文献
849.
A geothermometric technique based on equilibria between coexisting plagioclase and alkali feldspar was applied to quartzo-feldspathic granulites from Salvador, BA, Brazil. The conditions of metamorphism were determined to be in the range 750 ° C–800 ° C, 4–8 Kb, by comparison with experimental data on the stabilities of sapphirine, phlogopite and other minerals occurring in the associated rocks. Selected feldspar data gives temperatures near, but slightly below, this range. Several variants of the Wood and Banno model, as well as an empirical two-pyroxene geothermometer, were also tested and found to give temperatures which were apparently 50 °–100 ° high. The solubility of Al2O3 in orthopyroxene indicates temperatures which are about 200 ° to high, suggesting that Fe in the natural assemblages significantly changes relationships observed experimentally in MgO-Al2O3-SiO2 systems. 相似文献
850.
Diopside twins mechanically on two planes, (100) and (001), and the associated macroscopic twinning strains are identical (Raleigh and Talbot, 1967). An analysis based on crystal structural arguments predicts that both twin mechanisms involve shearing of the (100) octahedral layers (containing Ca2+, Mg2+ and Fe2+ ions) by a magnitude of c/2. Small adjustments or shuffles occur in the adjacent layers containing the [SiO4]4? tetrahedral chains. While the (100) twins are conventional with shear parallel to the composition plane, this analysis predicts that (001) twins form by a mechanism closely related to kinking. A polycrystalline diopside specimen was compressed 8% at a temperature of 400° C, a pressure of 16 kilobars, and a compressive strain rate of about 10?4/s. Transmission electron microscopy on this specimen has revealed four basic lamellar features:
- (100) mechanical twin lamellae;
- (100) glide bands containing unit dislocations;
- (001) twin lamellae;
- (101) lamellar features, not as yet identified.