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In this paper we analyze the presence of “Burgers solitons” in geologic porous rocks. These are quick, strong transients of combined fluid pressure and solute density that are generated from an adjacent matrix, characterized by an intense pressure and contaminant density. The effect that produces such transients is a nonlinear advection process that is not often taken into account in hydrologic science. A brief analysis of solitons in Pierre Shale is also shown in the paper.

We here analyze a new model of transients of pore pressure p and solute density ρ in geologic porous media. This model is rooted in the nonlinear wave theory, its focus is on advection and effect of large pressure jumps on strain. It takes into account nonlinear and also time-dependent versions of the Hooke law about stress, rate and strain. The model solutions strictly relate p and ρ evolving under the effect of a strong external stress. As a result, the presence of quick and sharp transients in low permeability rocks is unveiled, i.e., the nonlinear “Burgers solitons”. We, therefore, show that the actual transport process in porous rocks for large signals is not only the linear diffusion, but also a solitons presence could control the process. A test of a presence of solitons is applied to Pierre shale, Bearpaw shale, Boom clay and Oznam-Mugu silt and clay. An application about the presence of solitons for nuclear waste disposal and salt water intrusions is also discussed. Finally, in a kind of “theoretical experiment” we show that solitons could also be present in higher permeability rocks (Jordan and St. Peter sandstones), thus supporting the idea of a possible occurrence of osmosis also in sandstones.

In this study, current meter and hydrological data obtained during the X Italian Expedition in the Ross Sea (CLIMA Project) are analyzed. Our data show a nice agreement with previous data referring to the water masses present in this area and their dynamics. Here, they are used to further analyze the mixing and deepening processes of Deep Ice Shelf Water (DISW) over the northern shelf break of the Ross Sea. In more detail, our work is focused on the elementary mechanisms that are the most efficient in removing dense water from the shelf: either classical mixing effects or density currents that interact with some topographic irregularity in order to drop to deeper levels, or also the variability of the Antarctic Circumpolar Current (ACC) which, in its meandering, can push the dense water off the shelf, thus interrupting its geostrophic flow. We also discuss in detail the (partial) evidence of dramatic interactions of the dense water with bottom particulate, of geological or biological origin, thus generating impulsive or quasi-steady density-turbidity currents. This complex interaction allows one to consider bottom particular and dense water as a unique self-interacting system. In synthesis, this is a first tentative analysis of the effect of bottom particulate on the dense water dynamics in the Ross Sea.

[EN] The MOSCAB experiment (Materia OSCura A Bolle) uses the Geyser technique for dark matter search. The results of the first 0.5 kg mass prototype detector using superheated C3F8 liquid were very encouraging, achieving a 5 keV nuclear recoil threshold with high insensitivity to gamma radiation. Additionally, the technique seems to be easily scalable to higher masses for both in terms of complexity and costs, resulting in a very competitive technique for direct dark matter search, especially for the spin dependent case. Here, we report as well in the construction and commissioning of the big detector of 40 kg at the Milano-Bicocca University. The detector, the calibration tests and the evaluation of the background will be presented. Once demonstrated the functionality of the detector, it will be operated at the Gran Sasso National Laboratory in 2015., We acknowledge the financial support of the Spanish Ministerio de Ciencia e Innovación (MICINN) and Ministerio de Economía y Competitividad (MINECO), Grants FPA2012-37528-C02-02, and Consolider MultiDark CSD2009-00064, and of the Generalitat Valenciana, Grants ACOMP/2014/153 and PrometeoII/2014/079.

Hydrographic and current meter data, gathered in different periods in the Strait of Sicily and in the southern Tyrrhenian Sea, allow the outflow characteristics from the eastern toward the Western Mediterranean basin to be analyzed. The evolution through the strait of a deep vein of dense water coming from the Eastern Mediterranean is described, together with the dynamic interaction with overlying layers. These data are related to a slightly generalized version of recent density current models, such as those of Emms and those of Baringer and Price. Taking into account the dynamic influence of the overlying currents, and in particular their friction and mixing, this model explains the path of this deep flow and enables estimates of entrainment and bottom friction to be made. With these new data, a phenomenon of considerable interest, namely the dynamics of density currents crossing and outflowing from a strait, is examined and discussed.

Recently proposed criteria to identify sites, periods and characteristics of dense water formation in the Mediterranean Sea are analyzed. These criteria were first obtained through tank experiments and numerical and theoretical analyses. They can be useful for discriminating between processes that reach the sea bottom and those involving only the less thick superficial layers. With these criteria, general characteristics of newly formed dense water can be inferred from a knowledge only of winter density stratification g ′, of the buoyancy increase B due to the violent winter storms, and of the horizontal space scale R of the region of interest, a quantity usually identified by a decrease of 0.5–1°C of the SST. For the Mediterranean Sea, these criteria are applied here to the few known field observations and to more indirect “routine” information, namely climatological values of the stratification, numerical estimates of the buoyancy flux and remotely sensed SST from satellite imagery. In this way a stimulating picture of these dramatic phenomena is obtained, giving some insight into the possibility of forecasting and into other characteristics of dense water formation processes.

A novel model about mechanic and chemo-poroelastic (osmosis) coupling of fluids and solutes in fluid saturated porous media is here presented. This model is focused on non linear phenomena and does not apply the Osanger symmetry. Analyzing the action of a strong external stress we obtain two coupled non-linear equations for fluid pressure and solute (salt or pollutant) concentration. Their solutions in clay or shales unveil an unexpected presence of quick, non linear, strong transients of coupled pressure and solute, known in physics as Burger solitions. The presence of solitons may shed new light on flow processes, as about the origin of large hyperpressures.We also tested our model for sandstones assuming that a small, or very small, osmotic behavior could be there present. We found that Burgers solitons can be present in sandstones or other higher permeability rocks, as some Calabria rocks.

In the propagation of nonlinear waves in fluid saturated porous media, a key role is played by the Darcy law. In many cases one should take into account a realistic spatial or temporal variability of rock parameters, as permeability, porosity, diffusivity…To this purpose we here introduce a nonlocal Modified Darcy Law (MDL) by considering a fractional derivative generalization of the classical case. As an application we here study the effect of a generalized Darcy law on the propagation of nonlinear thermoelastic waves in porous media. In more details, we discuss an application of this MDL to an early Natale and Salusti model about quick and strong pressure and temperature waves in fluid saturated rocks. The original model leads to the Burgers equation, while with the MDL here we obtain a nonlocal formulation of the Burgers equation. We moreover find the analytic solution in the case that diffusion plays a secondary role. With this nonlocal model we obtain a richer analysis of realistic characteristic of such transient phenomena, in particular the spatial delays in wave propagation.

Shallow-water equations in a domain representing a strait are transformed into curvilinear coordinates concordant with the domain configuration and mapping the domain onto a rectangle with two opposite open boundaries. The initial boundary value problem for the equations in the form of contravariant fluxes is considered and compared with a reduced formulation of boundary conditions for equations linearized near the boundary. A method for numerical integration of the transformed boundary value problem is discussed. Particular attention is given to modification ensuring stable computation in the case of strong nonlinearity and variability of domain metric.

Thermal satellite images relative to the years 1997-2000, analyzed by Bignami et al. (2006), identify the sites of higher frequency in cold filaments in the Mediterranean Sea. The main zones in which these phenomena are seen to occur are characterised by the funnelling of strong cold winds by an irregular coastal orography. Intense air-sea interaction in the coastal zone is indeed known to generate a particularly strong input of potential vorticity into the sea, and this in turn gives origin to cold filaments and jets. These propagate offshore, often driven by the local currents. We therefore analyze thermal satellite images and CTD casts from the SYMPLEX 99 cruise (21 October - 6 November 1999), across a cold filament off Cape Passero, in the Sicily Channel. The filament width is 20 km; the thermal anomaly is 2 C; geostrophic and ADCP velocity data reveal that the filament is moving southward with velocities up to 60 cm s-1. Its salinity field has low values in the centre of the filament (about 37.4 psu at 40-60 m depth), while its temperature has classical outcropping isothermals (about 22-23.5 C) along the centre of the filament. All this suggests the interest of a generalized analysis of temperature, SST, salinty, density, velocity and potential vorticity along-flow evolution of this filament, seen as a set of potential vorticity stream-tubes. The analysis of these jets' evolution gives further insight into the characteristics of their detachment from the coast, alongflow warming, thickening, time-evolution of their velocity and other offshore properties.

The NEMO.RD Project is a feasibility study of a km 3 underwater telescope for high energy astrophysical neutrinos to be located in the Mediterranea Sea. At present this study concerns: i) Monte Carlo simulation study of the capabilities of various arrays of phototubes in order to determine the detector geometry that can optimize performance and cost; ii) design of low power consumption electronic cards for data acquisition and transmission to shore; iii) feasibility study of mechanics, deployment, connection and maintenance of such a detector in collaboration with petrol industries having experience of undersea operations; iv) oceanographic exploration of various sites in search for the optimal one. A brief report on the status of points i) and iv) is presented here.

Le mouvement unidimensionnel d'eau dense au niveau de la pente du fond marin et les interactions turbulentes eau-sable sont analyses par un modele non lineaire

The ANTARES collaboration is building a deep sea neutrino telescope in the Mediterranean Sea. This detector will cover a sensitive area of typically 0.1 km-squared and will be equipped with about 1000 optical modules. Each of these optical modules consists of a large area photomultiplier and its associated electronics housed in a pressure resistant glass sphere. The design of the ANTARES optical module, which is a key element of the detector, has been finalized following extensive R & D studies and is reviewed here in detail., 26 pages, 15 figures, to be published in NIM

To investigate thermodynamic currents in Antarctica, we here discuss quasi-steady density currents flowing over a regular slope and their hydrodynamic stability, considering also bottom erosion phenomena: in other words, the current is assumed to exchange sediments with the bottom. To simplify this complex problem a model of sediment evolution is assumed. As in recent work the excess mass due to the bottom erosion and deposition is assumed to depend only on the current stress on the bottom. A nonlinear equation considering both the time and space variability of these “density-turbidity” currents for a two-layer model is obtained and a novel criterion to identify the “ignition” point of these density-turbidity currents is discussed. In Polar Oceans these interactions can play a fundamental role in the generation of new water masses, as a result of violent hydrodynamic instability concerning the downslope motion of dense shelf water along submarine canyons.

The strait of Messina, separating Sicily from the Italian peninsula, has been studied since Homer’s times. Scientists have always been fascinated by its strong currents generated by the opposition of tidal phase between the two contiguous Tyrrhenian and Ionian basins. Tidal barotropic and baroclinic currents, up to 2 m/s, transient barotropic eddies and nonlinear wave trains as detected from remote and in situ observations and in the light of numerical models, are here analyzed and discussed.

The optical-absorption spectra of bulk silver measured by Liljenvall and Mathewson as a function of temperature have been fitted by means of a model calculation recently developed by one of the present authors. Optical gaps and interband optical matrix elements have been determined for several different temperatures.

We present a simple model of a steady barotropic eddy superimposed on a current, with varying Coriolis force, to study the structure of a nonlinear deformed eddy. We also develop the linearized time-dependent formulation of the problem. The resulting solutions are stable perturbations, with scales smaller than the eddy.

We discuss a theoretical model for pre-break-down electrical conduction related to carrier injection in semiconductors containing deep traps. A «pseudosubquadratic»J-V relationship is obtained by neglecting the contributions from the diffusion terms, in good agreement with the experimental results. A numerical approach is proposed to obtain theJ-V characteristics when the diffusion currents cannot be neglected.

A classical measurement of tides in the Messina strait made by Vercelli (1922–1923) is described. As Defant studied the same data with a linear barotropic model, a baroclinic, nonlinear theory is discussed. Some model equations are then discussed.

A nonlinear model of generation of internal «solitary» marine waves is discussed: when a large surface wave—for instance a superficial wave or a bore of tidal origin—passes over a submarine mountain or crosses a strait, packets of internal waves may often be detected. We study this phenomenon taking into account the effect of the air-sea surface; we show that the phenomenon can be schematized, in an approximate but realistic way, by using the solutions of an inhomogeneous KdV equation. The forcing term depends on the air-sea surface elevation and on the bottom topography. We then apply our model to the marine currents, of tidal origin, flowing through the straits of Gibraltar.

The linearized Navier- Stokes equations are studied in order to obtain a simple equation for the pressure in the sea. Taking into account the mobility of the free surface, a nonlinear differential equation is obtained: it describes the motion of the free surface, that is, the waves. The existence of an unique solution is shown and an approximation method is described.

Anisotropic diffusion of a tracer in a turbulent medium is considered. Once the neighbour concentration has been calculated, the evaluation of the tracer's concentration may be obtained by series expansion in terms of orthonormal functions. The harmonic-oscillator wave functions are suggested as a suitable choise. The ambiguities arising about the sign of the series coefficients are discussed. Die anisotrope Diffusion einer Beimengung in einem turbulenten Medium wird betrachtet. Nachdem man die Nachbarkonzentration berechnet hat, kann man die Konzentration der Beimengung mit Hilfe einer Reihenentwicktung nach orthonormalen Funktionen erhalten. Die Wellenfunktionen des harmonischen Oszillators werden als geeignetes System vorgeschlagen. Die Mehrdeutigkeiten, die sich aus der Vorzeichenwahl der Reihenkoeffizienten ergeben, werden diskutiert.

A bottom vein of dense water has been observed in the course of hydrological measurements carried out in three different periods—November 1980, February 1981 and June 1983—on the southern boundary of the shelf of the Adriatic Sea. The basin is renowned for cold, dense marine water generated in its northern portion by the Bora. Characteristic values of temperature, salinity and density of the central part of this vein of dense water are as follows: T ⋍ 13.70°C, S ⋍ 38.65‰ and σ 1 ⋍ 29.09 in November 1980; T ⋍ 12.4°C, S ⋍ 38.6‰, σ 1 ⋍ 29.3 in February 1981; and T ⋍ 12.52°C, S ⋍ 38.47‰ and σ 1 ⋍ 29.00 in June 1983. This water flows into the Southern Adriatic Trough, where it mixes with the Levantine type water. It follows the Italian shelf break at a depth of 100–300 m, gradually deepening until it reaches S. Maria di Leuca. The resulting water flows into the Ionian Sea through the Otranto Channel (740 m deep). An early hypothesis of Pollak is that this mixed water provides the main source of the abyssal water of the eastern Mediterranean Sea. A theoretical analysis, based on the classical steady model of Smith and a recent study by Shaw and Csanady, has allowed the fluxes to be estimated as 0.6–0.8 10 5 m 3 s −1 at the moment of maximum flux.

To evaluate the effect of external forces on the northern water motion of Adriatic Sea, we calculate the Green's Function of Laplace's tidal equation for a simple geometry. As an application, we use known data on sea level variations at various stations, in order to determine the external forces. We then compute the “theoretical” sea level at Venice. Its comparison with “experimental” data taken at Venice gives encouraging results. DOI: 10.1111/j.2153-3490.1979.tb00891.x

The evolution of the marine thermocline is studied by using some algebraic relations derived by Mellor and Durbin. In particular, a simple algebraic way to compute various turbulent quantities from experimental data is illustrated.

The time evolution of the thermocline in the Archipelago of La Maddalena in the Summer 1976, when a quick atmospheric front of western origin passed through the archipelago, is discussed. Large-amplitude internal waves are observed. We present and discuss the idea that they are generated through a mechanism of baroclinic compensation of the wind stress, strongly enhanced by the morphology of the archipelago.

Hydrological observations in the Ligurian Sea, north-western part of the Mediterranean Sea, are discussed. They show a steady cyclonic circulation. At theboundary of this circulation meanders and small eddies are rather frequent, in particular North of the Corsica Island. Their presence is in agreement with satellite data. In this paper also a number of simple baroclinic instability models are also considered, in an attempt to explain these current fluctuations.

Perturbation methods for the Laplace tidal equation, to determine both the eigenmodes and the time evolution of a marine system, are presented and discussed in detail. A simple way is given to describe the effect of the open boundary as an external force. An application to the Ligurian Sea is discussed.

The analysis of the currents and countercurrents in the Straits of Sicily, Sardinia, Corsica, Gibraltar and Messina is carried out as a review. The interest in these flows is connected with the fact that they essentially govern the main motion in the western Mediterranean basin. A discussion based on the models of Gill and Saint-Guily describing difficulties related to these nonlinear flows is also presented.

The shape of a deformed vortex in the presence of the Coriolis force is analyzed in a non-linear scheme. This formalism is used to explain a vortex that is located in the North Ligurian Sea. Some differences between experimental and theoretical results are discussed.

The marine currents inside the archipelago of La Maddalena between Sardinia and Corsica islands have been studied. The results of an implicit numerical barotropic unidimensional model are discussed and compared with experimental data.

Field and satellite observations of a superficial small-scale marine eddy (radius about 6 km, lying in the surface mixed layer, i.e., 50 to 100 m deep, with Rossby number ϵ i = 0.6 to 0.8 in the Ligurain Sea are discussed. The shape and the dynamical characteristics of the eddy have been compared with the results of theoretical models of baroclinic instability of the large-scale currents in the Ligurian Sea.

The velocity field, measured by Vercelli (1922-23) in the Strait of Messina hourly at six depths, is analysed to determine the size and the intensity of the energy-containing eddies. The analysis is performed by separating the turbulent component of the velocity field from the deterministic tidal component. The intensity of the turbulence is given by the averaged square of the aleatoric velocities. The size of the eddies is computed through correlation of the aleatoric velocities at different depths. Results show that the intensity of the turbulent field velocity is of the order of (50⤜60) cm s−1, while the size of the eddies is of the order of (20⤜45) m, reaching sometimes 70 m. These eddies are far beyond the inertial range predicted by the Kolmogorov theory. The eddies are due to Kelvin-Helmoltz shear instabilities between the surface and the deeper water.

In this note we first describe Eckart’s formulation of the fluidodynamics of oceans and atmosphere. We then analyse the mathematical structure of the problem and show that there is a unique solution of the evolution equations for a system with rigid boundary or without any boundary. We then describe a constructive method to determine the solutions.

In this paper an analytical method to study the hydrodynamic stability of simple barotropic, non-divergent flows is discussed. The method is based on the variational approach introduced by Arnold and derived from the Lyapunov stability criteria. In this context, the sufficient condition for the stability of a steady barotropic flow ψ(x,y) is obtained when dP(ψ)/dPψ = ψ, the derivative of the absolute vorticity P(ψ), is positive definite. In this case, we discuss the effect of higher derivatives dnP(ψ)/dψnψψ = ψ on the non-linear stability. Then we show that some classical examples of oceanic non-divergent flows (i.e. lee waves downstream an Island, steady flows through a Strait, the Fofonoff gyre) are stable to finite-amplitude perturbations.

Rhythmic motion of the ground (tremor) is often associated with activity before and during a volcanic eruption. Volcanic tremor is characterized by dominant peaks located in the 0.1–10 Hz range of the spectrum. In the light of previous formulations concerning the vibrations of a uniform vertical magma-filled pipe, this work presents the analysis of the motion when the section of the pipe is not constant but has constrictions and meanders. Our results show that the magma velocity modulus and pressure are inversely proportional to the pipe's cross-section. Consequently the effect of the motion of the magma gives rise to enlargements of the pipe's constrictions.

Generalizing an idea of Arnold, we discuss the hydrodynamic stability a la Lyapunov of solitary water-waves which are rotational solutions of the Euler equation, travelling with constant phase speed [ctilde]T. In the reference frame moving with the wave profile, the solitary wave is described by a solution of We show that if as in other applications of Arnold's idea, and if at the air sea surface, a rather realistic request, the system is stable for (a) small vertical or horizontal space scale perturbations; (b) perturbations with a very long vertical space scale and very small horizontal space scale or with a very long horizontal space scale and very small vertical space scale. Finally we show that the system is also stable for irrotational perturbations.

The effects of linear and nonlinear friction on the seiche's motion in the Adriatic sea have been studied trought a perturbative and numerical method. A roughness has been introduced to study the interaction with nonlinear friction term.