A simple boom assembly for the shipboard deployment of air-sea interaction instruments     

Edgar L. Andreas  John H. Rand  Stephen F. Ackley 《Ocean Engineering》1984,11(3):227-237

We have developed a simple boom for use in measuring meteorological variables from a ship. The main structural member of the boom, a triangular communications tower with rollers attached along its bottom side, is deployed horizontally from a long, flat deck, such as a helicopter deck, and will support a 100-kg payload at its outboard end. The boom is easy to deploy, requires minimal ship modifications, and provides ready access to the instruments mounted on it. And because it is designed for use with the ship crosswind, oceanographic work can go on at the same time as the air-sea interaction measurements.We describe our use of the boom on the Mikhail Somov during a cruise into the Antarctic sea ice and present some representative measurements made with instruments mounted on it. Theory, experiment, and our data all imply that instruments deployed windward from a rear helicopter deck can reach air undisturbed by the ship. Such an instrument site has clear advantages over the more customary mast, bow, or buoy locations.  相似文献   

Predicting significant wave height off the northeast coast of the United States   总被引：1，自引：0，他引：1  

Edgar L Andreas  Sinny Wang 《Ocean Engineering》2007,34(8-9):1328-1335

To develop a simple method to predict the significant wave height, we analyze 18 years of hourly observations from 12 different buoys that are off the northeast coast of the United States. Water depths ranged from 19 to 4427 m for these moored buoys. We find that, on average, all of these buoys exhibit a region of constant wave height for 10-m wind speeds between 0 and 4 m s⁻¹. That wave height does, however, depend on water depth. For wind speeds above 4 m s^–1, the wave height increases as the square of the wind speed; but the multiplicative factor is again a function of water depth. We synthesize these results in a prediction scheme that yields the significant wave height from simple functions of water depth and 10-m wind speed for wind speeds up to 25 m s^–1.  相似文献   

Thermodynamic mixing behavior of synthetic Ca-Tschermak–diopside pyroxene solid solutions: I. Volume and heat capacity of mixing     

Katja Etzel  Artur Benisek  Edgar Dachs  Lado Cemič 《Physics and Chemistry of Minerals》2007,34(10):733-746

The unite cell parameters and heat capacities of a series of synthetic clinopyroxenes on the join Ca-Tschermak (CaTs)−diopside (Di) were measured using X-ray powder diffraction and calorimetric methods, respectively. The volume of mixing at 298 K shows a negative asymmetric deviation from ideality. A two-parameter Margules fit to the data yields W _CaTs−Di ^V = −0.29 ± 0.11 cm³ mol⁻¹ and W _Di−CaTs ^V = −1.14 ± 0.14 cm³ mol⁻¹. Heat capacities were determined between 5 and 923 K by heat-pulse at 5−302 K and differential-scanning calorimetry at 143−923 K. The precision of the low and high temperature C _p data is better than ±1%. Polynomials of the form C _p = a + bT ^−1/2 + cT ⁻² + dT ⁻³ were fitted to the C _p data in the temperature range between 250 and 925 K. Thermal entropy values [S ₂₉₈ − S ₀] and [S ₉₀₀ −S ₀] as well as enthalpies [H ₂₉₈ − H ₀] and [H ₉₀₀ − H ₀] were calculated for all members of the solid solution series. No significant deviation from ideal mixing behavior was observed.  相似文献   

On the turbulent Prandtl number in the stable atmospheric boundary layer     

Andrey A. Grachev  Edgar L Andreas  Christopher W. Fairall  Peter S. Guest  P. Ola G. Persson 《Boundary-Layer Meteorology》2007,125(2):329-341

This study focuses on the behaviour of the turbulent Prandtl number, Pr _t , in the stable atmospheric boundary layer (SBL) based on measurements made during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA). It is found that Pr _t increases with increasing stability if Pr _t is plotted vs. gradient Richardson number, Ri; but at the same time, Pr _t decreases with increasing stability if Pr _t is plotted vs. flux Richardson number, Rf, or vs. ζ = z/L. This paradoxical behaviour of the turbulent Prandtl number in the SBL derives from the fact that plots of Pr _t vs. Ri (as well as vs. Rf and ζ) for individual 1-h observations and conventional bin-averaged values of the individual quantities have built-in correlation (or self-correlation) because of the shared variables. For independent estimates of how Pr _t behaves in very stable stratification, Pr _t is plotted against the bulk Richardson number; such plots have no built-in correlation. These plots based on the SHEBA data show that, on the average, Pr _t decreases with increasing stability and Pr _t < 1 in the very stable case. For specific heights and stabilities, though, the turbulent Prandtl number has more complicated behaviour in the SBL.  相似文献   

GROUND-WATER USE FOR NUCLEAR POWER PLANTS     

Edgar M. Smith 《Ground water》1978,16(5):352-353

Abstract. The uses of water for nuclear power plants consist of the following: service water, emergency cooling water, domestic (potable, sanitary), construction, and fire fighting. The quantity of water for these various uses may range from 10 gpm (0.63 1/s) for domestic supplies to greater than 100,000 gpm (6309 1/s) for service water and emergency cooling water supplies. Historically, the source of water for nuclear power plant use has been surface-water bodies, such as rivers, lakes, oceans, and man-made canals. Ground-water sources have supplied relatively small quantities of water for plant use, mainly domestic and construction supplies. A survey of 123 nuclear power plant sites which are either built, under construction, or planned, revealed that about 3 percent of all plant water supplies is derived from ground-water sources. Presently, four nuclear power plants intend to use ground water in relatively large quantities (as service water and emergency cooling water). Two of these plants will use ground water via induced infiltration from radial collector wells, and the other two plants intend to withdraw ground water from deep wells (1,000 feet) from a confined aquifer. Another plant, under construction, intends to use sewage effluent which is originally derived from a combination of surface and ground water.  相似文献   

A comment on ‘Agpaicity revisited: pattern recognition in the chemistry of nepheline syenite rocks’ by Dagbert et al.     

A.D Edgar 《Geochimica et cosmochimica acta》1977,41(3):439-440

The conclusions of Dagbertet al. (1975) on agpaicity are based on chemical and mineralogical data which may be characteristic of peralkalinity but not necessarily of agpaicity. Lack of significant variations in K in correspondence analysis can be explained on petrogenetic grounds and do not imply insignificance in agpaitic processes. The agpaitic coefficient merely indicates peralkalinity.  相似文献   

Significance of rare earth distributions in coexisting minerals of peralkaline undersaturated rocks     

B. J. Fryer  A. D. Edgar 《Contributions to Mineralogy and Petrology》1977,61(1):35-48

Rare earth element (REE) abundances in eudialytes and co-existing feldspars and mafic minerals from six alkaline intrusions ranging from mildly to strongly peralkaline indicate large scale complexing of the REE and yttrium. The eudialyte-bearing stages of these intrusions are characterized by a low Ce/Y ratio. This enrichment in the heavy REE is not due to the high REE content of the mineral eudialyte but appears to be related to the importance, duration and type of REE and other element complexing during differentiation. Feldspar and mafic mineral REE abundances reflect this low Ce/Y ratio and are often altered by late stage magmatic, metasomatic or hydrothermal fluids enriched in the heaviest REE and yttrium.  相似文献   

A high pressure-high temperature study of TiO₂ solubility in Mg-rich phlogopite: implications to phlogopite chemistry     

R.G Tronnes  A.D Edgar  M Arima 《Geochimica et cosmochimica acta》1985,49(11):2323-2329

The solubility of Tio₂ in phlogopites has been experimentally determined in the system K₂Mg₆Al₂Si₆O₂₀(OH)₄-K₂Mg₄TiAl₂Si₆O₂₀(OH)₄-K₂Mg₅TiAl₄Si₄O₂₀(OH)₄ between 825–1300°C and 10–30 kbar under vapour absent conditions. Starting compositions lie along the join K₂Mg₆Al₂Si₆O₂₀(OH)₄-K₂Mg_4.5TiAl₃Si₅O₂₀(OH)₄ which represents a combination of the Mg^[VI]2Si^[IV] = Ti^[VI]2Al^[VI] and $\text{2Mg}{}^{\mathrm{[VI]}}\text{=}\text{Ti}{}^{\mathrm{[VI]}}\text{□}{}^{\mathrm{[VI]}}$ substitution mechanisms for Ti in phlogopites. The results of the experiments indicate a systematic increase in solubility of Ti with increasing temperature and decreasing pressure for given bulk Tio₂ content. Under isobaric conditions high temperature Ti-saturated phlogopite breaks down to Ti-deficient phlogopite + rutile + vapour. Mass balance calculations suggest that the vapour phase may contain K₂O dissolved in H₂O and that the reaction is controlled by the vapour phase. Analyses of phlogopites coexisting with rutile and vapour can be represented in terms of the end-member components phlogopite [K₂Mg₆Al₂Si₆O₂₀(OH)₄], eastonite [K₂Mg₅Al₄Si₅O₂₀(OH)₄], an octahedral site deficient Ti-phlogopite (Ti-OSD) of composition K₂(Mg₄Ti□)Al₂Si₆)O₂₀(OH)₄, and Ti-eastonite [K₂Mg₅TiAl₄Si₄O₂₀(OH)₄]. With decreasing amounts of Ti in these phlogopites there is a decrease in the Ti-eastonite component and increase in the eastonite component.The general equation for the breakdown of Ti-phlogopite solid solution to Ti-free phlogopite + rutile + vapour is: 14 Ti-eastonite + 7 Ti-OSD ? 16 eastonite + 3 phlogopite + 21 rutile + 4 H₂O + 2 K₂O. Lack of knowledge of H₂O and K₂O activities in the vapour phase does not permit evaluation of thermodynamic constants for this reaction. The Ti solubility in phlogopites and hence its potential as a geothermobarometer under lower crustal to upper mantle conditions is likely controlled by common mantle minerals such as forsterite.  相似文献   

Some geophysical aspects of deep-sea drilling     

Thomas A. Davies  N. Terence Edgar 《Surveys in Geophysics》1974,1(4):391-407

More than 300 locations covering all the major ocean basins of the world, except the Arctic, have now been explored by deep-sea drilling. Results from deep-sea drilling permit the accurate calibration of seismic reflection profiles but at the same time emphasize the need for caution in interpreting the stratigraphic significance of such records. Basement ages determined from core samples are in close agreement with ages predicted by the concept of sea floor spreading, demonstrating both the validity of that concept and the validity of the paleomagnetic time scale. There also appears to be a demonstrable relationship between the age of the sea floor and its present depth. at many locations permits the documentation of changes in ocean currents, surface and bottom water temperatures, climate, and water depth.  相似文献   

A water balance model to estimate climate change impact on groundwater recharge in Yucatan Peninsula,Mexico     

Edgar Rodríguez-Huerta  Martí Rosas-Casals  Laura Margarita Hernández-Terrones 《水文科学杂志》2020,65(3):470-486

ABSTRACT

The aim of this paper is to estimate the effect that climate change will have on groundwater recharge at the Yucatan Peninsula, Mexico. The groundwater recharge is calculated from a monthly water balance model considering eight methods of potential and actual evapotranspiration. Historical data from 1961–2000 and climate model outputs from five downscaled general circulation models in the near horizon (2015–2039), with representative concentration pathway (RCP) 4.5 and 8.5 are used. The results estimate a recharge of 118 ± 33 mm·year^–1 (around 10% of precipitation) in the historical period. Considering the uncertainty from GCMs under different RCP and evapotranspiration scenarios, our monthly water balance model estimates a groundwater recharge of 92 ± 40 mm·year^–1 (RCP4.5) and 94 ± 38 mm·year^–1 (RCP8.5) which represent a reduction of 23% and 20%, respectively, a result that threatens the socio-ecological balance of the region.  相似文献