Approximation of the estimate error covariance function: Verification of the accuracy and generalization for the case of cross-covariance functions

Generalization of the approximation for the autocovariance function of estimate error, used frequently in four-dimensional analysis of the ocean's hydrophysical fields, is suggested for cross-covariance functions. It is shown that the principal properties of the covariance function of error estimate are not then violated. Approximation accuracy is studied through numerical experimentation using the two-dimensional equation for passive admixture transport as an example.Translated by V. Puchkin.     

Numerical modelling of tsunami propagation in the open Black Sea

This paper focuses on the numerical modelling of tsunami propagation in the open Black Sea. Two types of numerical models are discussed: a model for the radial propagation of long waves and an evolutionary finite-difference prognostic model. Experimentally derived numerical data on the model source of tsunamis are reported. Translated by Vladimir A. Puchkin.     

The interaction of surface waves in the presence of wind

Zakharov's equation is applied to study numerically the evolution of wave amplitudes. It is demonstrated that, owing to Krasitskii's new kernel functions, the system of surface waves remains Hamiltonian, in contrast to the former approaches used by Yuen, Lake, and Zakharov. If surface waves are wind-generated, they grow and become stochastic. If the effect of the waves on the wind is considered, then the wave amplitude evolution, similar to the no-wind case, continues to be recurrent. Translated by Vladimir A. Puchkin.     

Miocene extensional detachments in the outcropping basement of the northern Alboran Basin (Betics) and their tectonic implications

Whether or not there are extensional detachment faults in the Alboran basement can be tested directly because a part of the Alboran Basin is now emerged. These detachments, related to crustal thinning beneath the Alboran Basin, occurred from the Aquitanian to Tortonian. The resulting extensional geometries can be described in general terms. During the Serravalian a considerable southwest extension of the basin took place, accompanied by south-southeast extension in the northern Gibraltar Arc. Other detachments affected by Serravalian extension can be found. The spreading of the Alboran was nearly coeval with roughly westward migration of the Gibraltar mountain front.     

Wave climate in a groin field

Wave records at seven different locations within a groin field have been analysed by both statistical and spectral approaches to study the general wave climate. The wave heights and periods from the wave records were obtained by both upcross and downcross methods for the statistical approach. The variation of different wave height and wave period parameters with respect to the time of measurement at a particular location and its variation at different locations within the groin field at a particular instant of time are presented and discussed in detail in this paper. It is generally found that the wave heights follow the Weibull distribution.     

Metal accumulation in mussels of the Kuril Islands, north-west Pacific Ocean

Concentrations of cadmium, copper, iron, lead, manganese, nickel and zinc were investigated in two species of mussel from the Kuril Islands in the north-western Pacific Ocean: the short-lived mussel Mytilus trossulus and the much larger and longer-lived Crenomytilus grayanus. The concentrations of most elements were low, and these reported levels are believed to reflect background values for pristine locations. However, both iron and zinc concentrations were elevated in some samples taken from areas of hydrothermal vent activity, and these are believed to reflect the enrichment of the two metals in solution at such sites. Furthermore, the concentrations of cadmium were unusually elevated in both species of mussel, especially in the longer-lived C. grayanus. The high accumulation of cadmium in mussels from the Kuril Islands is believed to reflect regional upwelling, but it is also postulated that filtration rates of the mussels are high due to low levels of suspended matter, and this leads to a high assimilation efficiency for cadmium. The distribution of cadmium amongst the tissues of C. grayanus is also reported, and the need for further ecotoxicological studies in the area is proposed.     

A hydrodynamic model of a submerged lenticular wave energy device

The wavemaking capability and energy absorbing characteristics of a single submerged body, constrained to move horizontally in a surge mode, are examined. The body possesses both a vertical axis of symmetry and a horizontal plane of symmetry and is ‘thin’ in the sense that the body draft is small compared to the length. The behaviour of a single body subject to a constraint being placed upon the amplitude of its displacement and the properties of an array of interacting identical devices are also discussed.     

3,4-benzopyrene and perylene in mussels, Mytilus sp., from the Laguna Veneta,North-East Italy

From July, 1975 to November, 1976 mussels from the Laguna Veneta, north-east Italy, and the adjacent Adriatic Sea were collected bimonthly at ten stations and analysed for 3,4-benzopyrene (BaP) and perylene (Pe) content. Mean concentrations were in the range 12·0–135·1 μg/kg dry weight for BaP and 1·5–16·9 μg/kg for Pe, but values as high as 327 μg/kg for BaP and 71 μg/kg for Pe have been measured. The distribution of BaP and Pe closely matches previous results on petroleum hydrocarbon contamination in mussels from this area and indicates that the major portion of BaP and Pe in these bivalves is due principally to human activities.