PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 15

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available remote On the nonlinear internal waves propagating in an inhomogeneous shallow sea
Massel S. R.
Oceanologia
|
2016
|
No. 58 (2)
59--70
EN
A concept of conservation of energy flux for the internal waves propagating in an inhomogeneous shallow water is examined. The emphasis is put on an application of solution of the Korteweg–de Vries (KdV) equation in a prescribed form of the cnoidal and solitary waves. Numerical simulations were applied for the southern Baltic Sea, along a transect from the Bornholm Basin, through the Słupsk Sill and Słupsk Furrow to the Gdańsk Basin. Three-layer density structure typical for the Baltic Sea has been considered. An increase of wave height and decrease of phase speed with shallowing water depth was clearly demonstrated. The internal wave dynamics on both sides of the Słupsk Sill was found to be different due to different vertical density stratification in these areas. The bottom friction has only negligible influence on dynamics of internal waves, while shearing instability may be important only for very high waves. Area of possible instability, expressed in terms of the Richardson number Ri, is very small, and located within the non-uniform density layer, close to the interface with upper uniform layer. Kinematic breaking criteria have been examined and critical internal wave heights have been determined.
2
Content available remote Surface wave generation due to glacier calving
Massel S.R., Przyborska A.
Oceanologia
|
2013
|
No. 55 (1)
101-127
EN
Coastal glaciers reach the ocean in a spectacular process called "calving". Immediately after calving, the impulsive surface waves are generated, sometimes of large height. These waves are particularly dangerous for vessels sailing close to the glacier fronts. The paper presents a theoretical model of surface wave generation due to glacier calving. To explain the wave generation process, four case studies of ice blocks falling into water are discussed: a cylindrical ice block of small thickness impacting on water, an ice column sliding into water without impact, a large ice block falling on to water with a pressure impulse, and an ice column becoming detached from the glacier wall and falling on to the sea surface. These case studies encompass simplified, selected modes of the glacier calving, which can be treated in a theoretical way. Example calculations illustrate the predicted time series of surface elevations for each mode of glacier calving.
3
Content available remote Modelling flow in the porous bottom of the Barents Sea shelf
Massel S.R.
Oceanologia
|
2013
|
No. 55 (1)
129-146
EN
In their recent paper, Węsławski et al. (2012) showed that the Svalbardbanken area of the Barents Sea is characterized by a high organic carbon settlement to the permeable sea bed, which consists of gravel and shell fragments of glacial origin. In the present paper, which can be considered as a supplement to the Węsławski et al. paper, two potential hydrodynamic mechanisms of downward pore water transport into porous media are discussed in detail. In particular, estimated statistical characteristics of the pore water flow, induced by storm surface waves, indicate that the discharge of water flow can be substantial, even at large water depths. During stormy weather (wind velocity V=15 m s-1 and wind fetch X =200 km) as much as 117.2 and 26.1 m3 hour-1 of water filter through the upper 5 m of the shell pit at water depths of 30 and 50 m respectively. For a porous layer of greater thickness, the mean flow discharge is even bigger. The second possible mechanism of flow penetration in the porous layer is based on the concept of geostrophic flow and spiral formation within the Ekman layer. Assuming that the current velocity in the near-bottom water layer is u- = 1 m, the resulting mean discharge through this layer becomes as large as 0.99 and 0.09 m3 s-1 for downstream and transverse flows respectively.
4
Content available remote On the geometry of ocean surface waves
Massel S.R.
Oceanologia
|
2011
|
No. 53 (2)
521-548
EN
The factors influencing the atmosphere-ocean transfer of mass and momentum, as well as incipient wave breaking and the amount of energy dissipated due to breaking, are discussed in detail. In particular, the influence of directional spreading on the statistics of surface wave slopes and the area of the wind-roughened ocean surface is demonstrated. Theoretical analysis and comparison with the available experimental data show that unimodal directional spreading is not able to reproduce the observed ratio of the cross-wind/up-wind mean square slopes. Better agreement is achieved when bimodal directional spreading, consisting of two wrapped-Gaussian distributions, is applied. The bimodal form suggested by Ewans (1998) is used in the paper. Moreover, the formulae developed here show that the increase in the area due to surface waves is rather small for both regular and irregular waves.
5
Content available remote Surface waves in deep and shallow waters
Massel S.R.
Oceanologia
|
2010
|
No. 52 (1)
5-52
EN
The motion of water due to surface waves is the most dynamic factor observed in the marine environment. In this review various aspects of the wave modelling of non-linear, steep surface waves and their role in the atmosphere-ocean interaction are discussed. Significant improvements in wave forecasting have been made in the last ten years. This is to a large extent related to substantial progress in the description of wind forcing and other processes, as well as to the more efficient use of satellite observations and assimilation methods. One striking observation is the increasing variety and complexity of models in which more physical processes are implemented, greater precision and resolution achieved and extended ranges of applicability demonstrated. However in order to evaluate the applicability of particular models, comparison with high quality experimental data, collected in nature or under laboratory conditions, is necessary.
6
Content available remote Water dynamics in estuaries along the Polish Baltic coast
Jasińska E., Massel S.R.
Oceanological and Hydrobiological Studies
|
2007
|
Vol. 36, No.2
101-133
EN
Estuaries are areas where river and sea waters meet. Therefore, the hydrodynamical, hydrochemical, and hydrobiological processes in the estuaries are typical for both environments. The most important processes, which play leading roles in estuaries include the dynamics of water flow, water quality, and the mixing of water of different biochemical characteristics. This paper is divided into two parts. In the first, basic hydrodynamical processes are described and analytical and numerical methods of evaluating them are presented. Part two illustrates these processes using experimental data and the results of mathematical modeling for some estuaries along the Polish Baltic coast.
7
Content available remote Experiments on wave motion and suspended sediment concentration at Nang Hai, Can Gio mangrove forest, Southern Vietnam
Hong Phuoc V.L., Massel S.R.
Oceanologia
|
2006
|
No. 48 (1)
23-40
EN
Biogeochemical and trophodynamic processes as well as hydrodynamic factors play a major role in the structure and function of mangrove ecosystems. This study outlines field experiments on wave motion and suspended sediment concentration carried out at Nang Hai, Can Gio mangrove forest, Southern Vietnam. Pressure sensors were used to measure sea surface elevation, and Optical Backscatter Sensors (OBS) were applied to detect infrared (IR) radiation scattered from suspended particles in order to measure turbidity and suspended sediment concentrations. The experimental results indicate that most of the energy is dissipated inside the mangrove forest as a result of wave-trunk interactions and wave breaking. The suspended sediment concentration depends on wave intensity and tidal current velocity. Wave action is one of the main factors forcing sediment transport and coastal erosion at the study site; even the wave field at the study site is not so strong. The establishment of mangrove vegetation can encourage the deposition of sediment, or at least the retention of the flood-tide sediment influx.
8
Content available remote Basis for a valuation of the Polish Exclusive Economic Zone of the Baltic Sea: Rationale and quest for tools
Węsławski J.M., Andrulewicz E., Kotwicki L., Kuzebski E., Lewandowski A., Linkowski T., Massel S.R., Musielak S., Olańczuk-Neyman A., Pempkowiak J., Piekarek-Jankowska H., Radziejewska T., Różyński G., Sagan I., Skóra K. E., Szefler K., Urbański J., Witek Z., Wołowicz M., Zachowicz J., Zarzycki T.
Oceanologia
|
2006
|
No. 48 (1)
145-167
EN
This paper summarises current knowledge of goods and services in the Polish Exclusive Economic Zone of the Baltic Sea ecosystem. It reviews specific properties of the Baltic that could be used for economic valuation. Goods and services range from the familiar resources of fish and minerals, which were valued with the Productivity Method, to less obvious services provided by the ecosystem such as biofiltration in coastal sands, valued with either the Replacement Cost or Damage Cost Avoided methods. Disservices to the marine ecosystem are also considered, e.g. erosion and coastal flooding, including the costs of planned mitigating measures. This paper emphasises the importance of using valuation methods to help make better-educated decisions for the sustainability of the Baltic Sea.
9
Content available remote Attenuation of wave-induced groundwater pressure in shallow water. Part 2. Theory
Massel S. R., Przyborska A., Przyborski M.
Oceanologia
|
2005
|
No. 47 (3)
291-323
EN
In this Part 2 of the paper (Part 1 was published by Massel et al. 2004) an exact close-form solution for the pore-water pressure component and velocity circulation pattern induced by surface waves is developed. This comprehensive theoretical model, based on Biot's theory, takes into account soil deformations, volume change and pore-water flow. The calculations indicate that for the stiffness ratio G/E'w ? 100, the vertical distribution of the pore pressure becomes very close to the Moshagen & T?rum (1975) approach, when the soil is rigid and the fluid is incompressible. The theoretical results of the paper have been compared with the experimental data collected during the laboratory experiment in the Large Wave Channel in Hannover (see Massel et al. 2004) and showed very good agreement. The apparent bulk modulus of pore water was not determined in the experiment but was estimated from the best fit of the experimental pore-water pressure with the theoretical one. In the paper only a horizontal bottom is considered and the case of an undulating bottom will be dealt with in another paper.
10
Content available remote Attenuation of wave-induced groundwater pressure in shallow water. Part 1
Massel S. R., Przyborska A., Przyborski M.
Oceanologia
|
2004
|
No. 46 (3)
383-404
EN
A coastal aquifer has a dynamic seaward boundary at the beach face where physical and ecological processes are influenced by oceanic water level fluctuations. Many basic groundwater concepts and the role of the impact of groundwater seepage on beach ecosystems are still poorly understood. Studies are needed to improve our understanding of the relationships between surface and subsurface flow processes on beaches. This is particularly helpful in clarifying the interaction of the physical processes, biodiversity and productivity of sandy beaches, sediment transport and coastal structure stability and modern beach nourishment techniques. As the estimation of infiltration into beach sand is very difficult to carry out under real sea conditions, a control led large-scale laboratory experiment was carried out in the Large Wave Channel in Hannover (Germany) as part of a project supported by the European Community (contract HPRI-CT-2001-00157). First part of the paper describes the technology applied in the experiment and reports some preliminary results.
11
Content available remote Wave-induced set-up and flow over shoals and coral reefs. Part 1. A simplified bottom geometry case
Massel S.R., Brinkman R. M.
Oceanologia
|
2001
|
No. 43 (4)
373-388
EN
An analytical approach was used to model the wave-induced set-up and flow through simple shoal geometry when water depth is a linear function of the distance. Two different approaches were applied to parameterize the energy dissipation due to wave breaking. The resulting set-up height and flow velocity were determined and their dependence on the geometry of the shoal and offshore forcing was demonstrated. The extension of the solution to a more complicated bathymetry and verification against the experimental data will be given in the second part of the paper.
12
Content available remote Run-up of dispersive and breaking waves on beaches
Massel S.R., Pelinovsky E. N.
Oceanologia
|
2001
|
No. 43 (1)
61-97
EN
Transformation of waves on sandy beaches, their breaking, set-up and run-up are the main factors contributing to fluctuations in the water table and groundwater flow. In this paper, the run-up mechanisms have been studied using analytical models. In contrast to the standard models, the waves approaching the shoreline are assumed to be dispersive and the equivalence of the non-linear and linear solutions for the extreme characteristics of wave run-up, such as the height of maximum run-up and the velocity of run-up, are used. A linear system of equations for the run-up of breaking waves is developed. This system is based on the application of the mild-slope equation in the deeper area, where waves are dispersive, while the linear equations of shallow water are applied close to the shoreline, where the water depth is a linear function of distance. The dissipation factor in the shallow water equation has been formulated using its resemblance to the mild-slope equation for a non-permeable sea bottom. Application of the method is illustrated for various bottom profiles and wave characteristics, and theoretical results compared well with experimental data. These solutions of the run-up phenomena will assist future studies on wave-induced beach groundwater flow.
13
Content available remote Experimental study of the formation of steep waves and breakers [commun.]
Massel S.R., Tęgowski J., Chomka M., Wichorowski M., Dąbrowski J., Stansberg C. T., Moe V.
Oceanologia
|
2001
|
No. 43 (3)
353-363
EN
Breaking waves (whitecaps) are one of the most important and least understood processes associated with the evolution of the surface gravity wave field in the open sea. This process is the principal means by which energy and momentum are transferred away from a developing sea. However, an estimation of the frequency of breaking waves or the fraction of sea surface covered by whitecaps and the amount of dissipated energy induced by breaking is very difficult to carry out under real sea conditions. A controlled experiment, funded by the European Commission under the Improving Human Potential Access Infrastructures programme, was carried out in the Ocean Basin Laboratory at MARINTEK, Trondheim (Norway). Simulation of random waves of the prescribed spectra by wave makers provided a very realistic pattern of the sea surface. The number of breaking waves was estimated by photographing the sea surface and recording the noise caused by the breaking waves. The experimental data will serve for calibration of the theoretical models of the sea surface fraction related to the whitecaps.
14
Content available remote Circulation of groundwater due to wave set-up on a permeable beach
Massel S.R.
Oceanologia
|
2001
|
No. 43 (3)
279-290
EN
Sandy beaches are highly exploited but very dynamic and fragile environments. Driven by waves, the water flow through the beach body is able to transport oxygen, and hence help to maintain biological activity in the porous media. The paper presents a theoretical attempt to predict the groundwater circulation due to wave set-up. Two systems of circulations have been discovered, related to two different gradients of the set-up height. For the offshore gradient, the horizontal excess pressure gradient induces flow in the offshore direction. However, closer to the shore, the pressure gradient is reversed and the resulting flow moves shorewards.
15
Content available remote Znaczenie czynnika ekologicznego w inżynierii morskiej
Massel S. R.
Inżynieria Morska i Geotechnika
|
2001
|
nr 6
343-347
PL
Wpływ działalności człowieka na morskie środowisko przybrzeżne. Projektowanie budowli morskich na obszarach wrażliwych ekologicznie wraz z zaleceniami projektowymi.
EN
Influence of mankind activity on marine coastal environment. Design of marine engineering structures in the area sensitive to ecology together with designing recommendations.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.