Short gravity and capillary wave spectra from tower-based radar     

Lawner  R. Moore  R. 《Oceanic Engineering, IEEE Journal of》1984,9(5):317-324

Radar backscatter measurements made as part of Project MARSEN in 1979 from the Noordwijk tower off the Dutch coast are used to calculate apparent ripple (capillary and short-gravity wave) spectra by inverting the small-perturbation scattering theory. The measurements were made at 10 and 15 GHz for angles of incidence ranging from20degto70deg; this means that the range of Bragg-resonant spatial wavenumbers covered is from 1.43 to 5.90 cm^-1. Results of coincidentC- andX-band experiments by the Institute Francais du Petrole (IFP) andX-band experiments by a group of Dutch researchers (TNO) are compared with our results and good general agreement is found. Our initial results show a steeper falloff of the spectra with increasing wavenumber than reported previously, particularly at low windspeeds. When the spectra are modified to account for the difference between previous aircraft and tower measurements [1], the observed spectra agree well with the appropriate part of Pierson's wave spectrum as modified by Fung and Lee [2].  相似文献   

THE WILLOWBAR METEORITE*     

David E. Lange  Carleton B. Moore  Kendall Rhoton 《Meteoritics & planetary science》1973,8(3):263-275

The Willowbar, Oklahoma meteorite was found by Kendall Rhoton in December, 1971, lat 36° 44′ N.; long 102° 12′ W. It is a shocked brecciated L6 chondrite (Fa-24.3) with large black veins cutting areas of normal chondritic texture. It weighed 2.07 kg.  相似文献   

Explicit formula for the geoid-quasigeoid separation   总被引：1，自引：0，他引：1  

R. Tenzer  P. Novák  P. Moore  M. Kuhn  P. Vaníček 《Studia Geophysica et Geodaetica》2006,50(4):607-618

The explicit formula for the geoid-to-quasigeoid correction is derived in this paper. On comparing the geoidal height and height anomaly, this correction is found to be a function of the mean value of gravity disturbance along the plumbline within the topography. To evaluate the mean gravity disturbance, the gravity field of the Earth is decomposed into components generated by masses within the geoid, topography and atmosphere. Newton’s integration is then used for the computation of topography-and atmosphere-generated components of the mean gravity, while the combined solution for the downward continuation of gravity anomalies and Stokes’ boundary-value problem is utilized in computing the component of mean gravity disturbance generated by mass irregularities within the geoid. On application of this explicit formulism a theoretical accuracy of a few millimetres can be achieved in evaluation of the geoid-to-quasigeoid correction. However, the real accuracy could be lower due to deficiencies within the numerical methods and to errors within the input data (digital terrain and density models and gravity observations).  相似文献   

Two dimensional transient fundamental solution due to suddenly applied load in a half-space     

F. Guan  I.D. Moore  C.C. Spyrakos 《Soil Dynamics and Earthquake Engineering》1998,17(4):269-277

A transient Green function due to suddenly applied line loads in an isotropic and homogeneous half-space is reported in this paper. The derivation of the half-space Green function in the Laplace and the Fourier transform spaces is first reviewed. Following an explicit inversion of the Fourier transform, the inverse Laplace transform is implemented along the contour integral on the p-complex plane in an integral form. The half-space Green function consists of full-space Green functions and a singularity-free complementary term. It can be easily incorporated into current transient boundary elements using the transient full-space Green function. Combined with finite elements, the half-space Green function can be used in a hybrid procedure to solve transient half-space problems without discretization of the free surface. Numerical results are presented to illustrate transient wave propagation in a half-space.  相似文献   

Application of226Ra,228Ra,223Ra, and224Ra in coastal waters to assessing coastal mixing rates and groundwater discharge to oceans     

Willard S. Moore 《Journal of Earth System Science》1998,107(4):343-349

The fate of dissolved material delivered to the coastal ocean depends on its reactivity and the rate at which it is mixed offshore. To measure the rate of exchange of coastal waters, we employ two short-lived radium isotopes,²²³Ra and²²⁴Ra. Along the coast of South Carolina, shore-perpendicular profiles of²²³Ra and²²⁴Ra in surface waters show consistent gradients which may be modeled to yield eddy diffusion coefficients of 350–540 m²s⁻¹. Coupling the exchange rate with offshore concentration gradients yields estimates of offshore fluxes of dissolved materials. For systems in steady state, the offshore fluxes must be balanced by new inputs from rivers, groundwater, sewers or other sources. Two tracers that show promise in evaluating groundwater input are barium and²²⁶Ra. These tracers have high relative concentrations in the fluids and low-reactivity in the coastal ocean. Applying the eddy diffusion coefficients to the offshore gradient of²²⁶Ra concentration provides an estimate of the offshore flux of²²⁶Ra. Measuring the concentrations of²²⁶Ra in subsurface fluids provides an estimate of the fluid flux necessary to provide the²²⁶Ra. These estimates indicate that the volume of groundwater required to support these fluxes is of the order of 40% of the surface water flow.  相似文献   

Mid-infrared imaging of WL 16: the spatial distribution of the hydrocarbon emission features     

Moore  Emerson  Skinner  Meixner  Arens  & Jernigan 《Monthly notices of the Royal Astronomical Society》1998,299(4):1209-1214

We present arcsec-resolution images at 8.2, 10.0 and 11.3 μm of the unusual young object WL 16 in Ophiuchus, which has an extended envelope of fluorescing hydrocarbon molecules. To the limit of achieved sensitivity, the faint 10.0-μm continuum has a surface-brightness distribution that is not distinguishable from those at 8.2 and 11.3 μm, where the luminosity is known to be dominated by the polycyclic aromatic hydrocarbon (PAH) emission features. We conclude that the 10-μm continuum either arises from non-equilibrium heating of small dust grains that are well mixed with the hydrocarbons or is quasi-continuous emission from the PAH particles themselves, rather than thermal equilibrium emission from macroscopic dust grains, and that there is no significant silicate absorption variation across the source. The extended hydrocarbon emission may trace a flattened, equatorial distribution of circumstellar material or arise in bipolar lobes. The former case is slightly favoured, based on currently available data, and would imply that WL 16 is a relatively evolved Herbig Ae star, the equatorial plane of which has been almost cleared of normal dust, leaving only fluorescing hydrocarbons and larger coagulated particles as a possibly transient fossil of the original circumstellar disc.  相似文献   

Influence of an americium solid phase on americium concentrations in solutions     

Dhanpat Rai  R.G. Strickert  D.A. Moore  R.J. Serne 《Geochimica et cosmochimica acta》1981,45(11):2257-2265

Americium-241 concentrations in solutions contacting contaminated sediments for up to 2 yr were measured as a function of pH. Steady-state concentrations were reached within a few days. The solubility-limited Am concentration was found to decrease approximately 10-fold with one unit increase in pH. The log equilibrium constant for the solubility of Am_(soil) solid $\text{[Am}{}_{\mathrm{(soil)}}\text{+ H}{}^{\mathrm{+}}\text{? Am}{}_{\mathrm{(aq\; complex)}}{}^{\mathrm{+}}\text{]}$ was found to be ?4.12. The predictions based upon thermodynamic data suggest that Am_{(aq complex)}⁺ is likely to be Am(OH)₂⁺. Although the chemical formula of Am_(soil) was not determined, it does not appear to be Am(OH)₃(a).Published data on sorption coefficients of Am by different rocks, soils, and minerals were critically evaluated. Final Am solution concentrations calculated from the sorption coefficients of a variety of earth materials with several solutions agreed well with the concentrations predicted from the solubility of Am_(soil) solid, indicating that the sorption coefficient data are controlled by Am precipitation.  相似文献   

Fluxes of uranium and thorium series isotopes in the Santa Barbara Basin     

Willard S. Moore  Kenneth W. Bruland  Jacqueline Michel 《Earth and Planetary Science Letters》1981,53(3):391-399

Samples from the MANOP Santa Barbara Basin sediment trap intercomparison were analyzed for the isotopes of uranium, thorium, radium, lead, and polonium. All of the traps showed approximately the same compositions and isotopic ratios, indicating that they trapped similar materials. The²³⁴Th flux via falling particles was very close to the flux predicted from the production and scavenging rates of²³⁴Th from the water column. The²¹⁰Pb content of the trapped particles and the surface sediments were the same, however, the measured flux of²¹⁰Pb was seven times greater than the predicted flux. Predicted and measured fluxes of²²⁸Th and²¹⁰Po were similarly out of balance. To explain this apparent inconsistency, we suggest (as others have done) that the Santa Barbara Basin is an area where scavenging from the water column is intensified and where sediments deposited initially on the margins may be physically remobilized on a short time scale. These two effects increase the apparent area from which the basin derives the longer-lived isotopes but does not increase significantly the supply of the short-lived²³⁴Th.  相似文献   

Sea level events and Pleistocene coral ages in the northern Bahamas     

A.Conrad Neumann  Willard S. Moore 《Quaternary Research》1975,5(2):215-224

Emergent Pleistocene sea level indicators in the northern Bahamas include: a bioerosional notch at +5.3 to 5.9 m; sea caves, notches, and marine terraces at about +4.3 m; and lithified coral rubble and reef deposits between 0 and 3 m. Thorium 230 dates of the fossil corals, which were deposited as these features were being produced, span the age range from 100 to 145 thousand years BP with a majority falling between 115 and 130 thousand years BP. The notch at about +5.6 m is interpreted to be the product of a sea level stand 125 thousand years BP, while the features at +4.3 m are believed to be formed sometime later as sea level fell from the higher position. Part of the age span is inherent in the dating technique and possible sample alteration. Another cause of the spread may be mixing of corals of different ages into a single deposit.  相似文献   

The behaviour of dissolved organic material,iron and manganese in estuarine mixing     

R.M. Moore  J.D. Burton  P.J.LeB. Williams  M.L. Young 《Geochimica et cosmochimica acta》1979,43(6):919-926

Fractionation by ultra-filtration of the dissolved organic material (DOM) in the River Beaulieu, with typical concentrations of dissolved organic carbon (DOC) of 7–8 mg C/l, showed it to be mainly in the nominal molecular weight range of 10³–10⁵, with 16–23% of the total DOC in the fraction > 10⁵. The molecular weight distribution of DOM in the more alkaline River Test (average DOC, 2 mg C/l) was similar. In the River Beaulieu water, containing 136–314 βg Fe/l in ‘dissolved’ forms, 90% or more of this Fe was in the nominal molecular weight fraction > 10⁵. Experiments showed that DOM of nominal molecular weight <10⁵ could stabilize Fe(III) in ‘dissolved’ forms. The concentrations of ‘dissolved’ Fe in the river water probably reflect the presence of colloidal Fe stabilized by organic material and this process may influence the apparent molecular weight of the DOM. Dissolved. Mn (100–136 βg/l) in the River Beaulieu was mainly in true solution, probably as Mn(II), with some 30% in forms of molecular weight greater than ca 10⁴.During mi xing in the Beaulieu Estuary, DOC and dissolved Mn behave essentially conservatively. This contrasts with the removal of a large fraction of the dissolved Fe (Holliday and LISS, 1976, Est. Coastal Mar. Sci. 4, 349–353). Concentrations of lattice-held Fe and Mn in suspended particulate material were essentially uniform in the estuary, at 3.2 and 0.012%, respectively, whereas the non-lattice held fractions decreased markedly with increase in salinity. For Mn the decrease was linear and could be most simply accounted for by the physical mixing of riverborne and marine participates, although the possibility that some desorption occurs is not excluded. The non-linear decrease in the concentration of non-lattice held Fe in particulates reflected the more complex situation in which physical mixing is accompanied by removal of material from the ‘dissolved’ fraction.  相似文献