Some results of calculation bays amplification coefficients

The coefficients of bay amplification are investigated within the limits of the linear theory of long waves by analytical and analytical and numerical methods for periodic and solitary waves.     

Electron impact excitation rate coefficients of N II ion

This paper calculates the electron impact excitation rate coefficients from the ground term 2s²2p^{2 3}P to the excited terms of the 2s²2p², 2s2p³, 2s²2p3s, 2s²2p3p, and 2s²2p3d configurations of N II. In the calculations, multiconfiguration Dirac--Fork wave functions have been applied to describe the target-ion states and relativistic distorted-wave calculation has been performed to generate fine-structure collision strengths. The collision strengths are then averaged over a Maxwellian distribution of electron velocities in order to generate the effective collision strengths. The calculated rate coefficients are compared with available experimental and theoretical data, and some good agreements are found for the outer shell electron excitations. But for the inner shell electron excitations there are still some differences between the present calculations and available experiments.     

The calculation of carbonate ion concentration from total CO2 and titration alkalinity

A direct method involving a single iteration (a quadratic equation solved twice) is given for the calculation of carbonate ion concentration from total CO₂ and titration alkalinity. The simplified calculation should allow wider use of existing total CO₂ and titration alkalinity data.     

A BFG model for calculation of tidal current and diffusion of pollutants in nearshore areas

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Stability of ion pairs from gypsum solubility degree of ion pair formation between the major constituents of seawater

The stability constants of the ion pairs NaSO₄^?, KSO₄^?, MgSO₄^?, CaSO₄, MgCl⁺ and CaCl⁺ were determined at 25°C and 0.7 M formal ionic strength, by measuring the solubility of gypsum (CaSO₄ · 2H₂O) in different media. The media used contained one or two of the following electrolytes: NaCl, KCl, MgCl₂, NaClO₄, Mg(ClO₄)₂, Na₂SO₄. Values for the stability constants are 1.22, 1.84, 12.3, 30.6, 0.48 and 1.20 M^?1, respectively, and the solubility product for gypsum is 2.87 · 10^?4M². The distribution of the main constituents of seawater was calculated using these results and the values of the carbonate and bicarbonate constants given by Dyrssen and Hansson (1972–1973). The solubility of gypsum in seawater as calculated and determined experimentally was 21.43 mM and 21.10 mM, respectively.     

Diffusion of seawater ions. Part II. The role of activity coefficients and ion pairing

A theoretical evaluation of basic thermodynamic relationships reveals that variation of activity coefficients, ion pairing and electrical interactions must be considered when modelling ionic diffusion in seawater. The contributions of ion-pair formation and change in activity coefficient along the diffusion path were studied experimentally by conducting diffusion experiments in which solutions of KCl, NaCl, MgCl₂, Li₂SO₄, K₂SO₄, Na₂SO₄ and MgSO₄, at an ionic strength of 0.7, were allowed to diffuse into distilled water. The study reveals that the thermodynamic factor, required to correct for changes in the activity coefficient along the diffusion path, is significant for all the salts studied. Agreement between a simple diffusion model, which does not include ion pairing, and observed data was good for completely dissociated salts, but poor for salts which are known to form ion pairs at the concentration levels studied. The diffusion of MgSO₄, 0.425 of which is associated at I = 0.7, was successfully modelled by assuming that the diffusion coefficient of the MgSO₄⁰ ion pair is different from the diffusion coefficient of the dissociated salt. The diffusion coefficient of this ion pair is estimated to be 1.9 × 10⁻⁵ cm² s⁻¹ at 30°C, as compared to 0.49 × 10⁻⁵ cm² s⁻¹ for the dissociated salt. It is suggested that the high mobility of this ion pair could cause magnesium enrichment in pore water of sulfate depleted sediments.     

A comment on ‘MgSO4 ion association in seawater’ by Fisher,Gieskes and Hsu

Recently, the stoichiometric association constant for MgSO₄^o in seawater was presented as being inconsistent with thermodynamic data. The results obtained are refuted here as being inaccurate due to assumptions made concerning the activity coefficient of the MgSO₄^o ion pair.     

Stability of the calcium sulphate ion pair at the ionic strength of seawater by potentiometry

The stability of the ion pair CaSO₄ was determined from measurement of the change in calcium ion activity with medium composition at constant ionic strength. A calcium selective PVC-matrix liquid membrane electrode was used to monitor the calcium ion activity. All measurements were performed at 1 atm, 25 ± 0.1°C and 0.7 M formal ionic strength. The evaluation of the stability constant depends on the degree of complexation between calcium and chloride and between sodium and sulphate. The dependence of K_CaSO4, on K_NaSO4 and K_CaCl can be described by the following relations:K_CaSO4=17.7 K_CaCl+16.5 (K_NaSO4=1.8)K_CaSO4=18.8 K_CaCl+17.3 (K_NaSO4=2) for K_CaCl=0–1A value of K_CaSO4=25.4 is suggested.     

On the calculation of two-dimensional added mass and damping coefficients by simple Green's function technique

This paper describes a numerical method for calculating the two-dimensional hydrodynamic coefficients of one or two infinitely long, arbitrary cylinders forced to oscillate in or below the free water surface. The oscillation modes, amplitudes and phases of the cylinders may be different from one another. Finite water depth and a quay can be taken into account. Special consideration has been given to the radiation boundary conditions.The computer program developed has been tested in various two-dimensional boundary situations; it has produced results in good agreement with results obtained by other methods.     

On the calculation of extreme wave heights: A review

Over the past two decades there has been a great deal of interest in calculating design waves for offshore structures. This paper reviews the data limitations, statistical assumptions, distributions, fitting methods, and statistical tests used to determine confidence intervals and goodness of fit. Use is made of an illustrative example from the Grand Banks of Canada to indicate how a design wave could be calculated. It is concluded that no single method will be entirely suitable for all data sets.     

The study of oceanic turbulent diffusion

Journal of Oceanography - It is indeed a great honor to receive the Oceanographical Society of Japan Prize (1983) for the study of oceanic turbulent diffusion. For this award I owe a great many...     

A dynamic two-dimensional calculation of underwater lines

On the basis of a lumped mass method in two-dimension, we derive a dynamic calculation method for a system including both extensible and inextensible underwater lines. The Newmark beta method is used in numerical integration with respect to time. The Newton Raphson method is applied so that the numbers of iterations are reduced. A transient response of a line during deployment is calculated.     

The free-solution diffusion coefficient of boron: influence of dissolved organic matter

The free-solution diffusion coefficient for boron, which is necessary for diffusional flux calculations, was measured in a variety of media, including seawater, by the diaphragm-cell method. Results show that, over a wide range of solution compositions, the free-solution diffusion coefficient for boron, at ionic strengths of 0.5–0.6 M, is constant at 1.12 ± 0.02 × 10⁻⁵ cm² s⁻¹. In the presence of dissolved organic matter from pore waters of marine sediments, corresponding to 30 mg l⁻¹ dissolved organic carbon, boron diffusion is significantly slowed relative to other cases. Quantitative results allow calculation of a composite distribution coefficient that should be useful for approximately correcting total dissolved boron concentrations in marine sediments for organic-boron complexes.     

A note on small organism diffusion around an attractive center: A mathematical model

A mathematical model of small organism diffusion around an attractive center is presented. The diffusion equation includes a forcing term which creates a virtual flow of organisms toward the center. Owing to the attractive force, the organisms tend to collect in swarms or patches notwithstanding the diffusive motion of surrounding water.Contribution No. 176 of the Chesapeake Bay Institute, Department of Earth and Planetary Sciences, The Johns Hopkins University. This work was supported by the Office of Naval Research Contract N00014-67-A-0163-0006, Research Project NR083-016, by the U.S. Atomic Energy Commission under Contract AT (30-1) 3109, Document COO-3109-2, and by National Science Foundation Grant, GA-16603.     

A numerically effective calculation of sea water density

Accurate density calculation that includes pressure effects is achieved with negligible computational cost in the context of three-dimensional ocean modelling. Local linear (or quadratic) fits to the full UNESCO (Anon, 1981) equation of state can be used in many model applications where the potential temperature and salinity at a model grid point vary slightly in each model time step. The local polynomial fit is achieved by computing a Taylor series expansion about a local reference state. The terms in the Taylor series are calculated analytically for optimal accuracy and minimal computational cost. All calculations can be done with single precision arithmetic, without compromising accuracy. In a three-dimensional nonhydrostatic ocean model applied to a deep convection problem, the local density calculation reduced the total computational cost of the model by 7% relative to that when the full UNESCO density calculation was used. The computational advantage is 15% for an application in which the nonhydrostatic part of the calculation is turned off. The computational advantage is, however, a function of the nature of both the model being used and the problem being solved.The principal algorithms are coded in Fortran 90, fortran 77, and as Matlab functions. The complete set of routines and test programs is coded in Fortran 90.     

The diffusion coefficient of dissolved silica revisited

The diffusion coefficient of dissolved silica was determined for two different salinities, 36 and 0, at temperatures ranging from 2 °C to 30 °C and at an average pH value of 8.1. Our results show limited influence of salinity and a variation by a factor of 2 to 3 of the silica diffusion coefficient within the temperature range considered in this study. The values obtained at 25 °C are in agreement with previous work carried out at room temperature for seawater and freshwater. The dependency on temperature and viscosity of the diffusion coefficient agrees well with the Einstein–Stokes equation. The composition of the solvent appears to be an important factor because it modifies the viscosity and allows for the complexation of the dissolved silica with less mobile ions, while its pH controls the dissolved silica speciation. In seawater, the higher viscosity and the presence of dissociated and polymeric species result in a decrease of the diffusion coefficient compared to freshwater systems.     

Wind energy input to the Ekman-Stokes layer: Reply to comment by Jeff A. Polton

This reply corrects the estimate of the wind and wave energy inputs into the Ekman layer by using the Ekman-Stokes layer energy budget as suggested in Polton (2009). Using the data and method in Liu et al. (2007), the global wind energy input was recalculated. The estimated global total energy input to the Ekman-Stokes layer is 2.22 TW, including 1.93 TW direct wind energy input and 0.29 TW wave-induced energy input. Compared to that in Liu et al. (2007), the recalculated wave-induced energy input was increased by 0.03 TW.