Observations Of Stratification Research Articles

Hydrographical implications of ship-induced turbulence in stratified waters, studied through field observations and CFD modelling

Ship-related energy pollution has received increasing attention but almost exclusively regarding radiated underwater noise, while the effect of ship-induced turbulence is lacking in the literature. Here we present novel results regarding turbulent wake development, the interaction between ship-induced turbulence and stratification, and discuss the impact of turbulent ship wakes in the surface ocean, in areas with intense ship traffic. The turbulent wake development was studied in situ, using Acoustic Doppler Current Profilers (ADCP) and conductivity, temperature, depth (CTD) observations of stratification, and through computational fluid dynamics (CFD) modelling. Our results show that the turbulent wake interacts with natural hydrography by entraining water from below the pycnocline, and that stratification influences the turbulent wake development by dampening the vertical extent, resulting in the wake water spreading out along the pycnocline rather than at the surface. The depth and intensity of the turbulent wake represent an unnatural occurrence of turbulence in the surface ocean. The ship-induced turbulence can impact local hydrography, nutrient dynamics and increase plankton mortality due to physical disturbance, especially in areas with intense traffic. Therefore, sampling and modelling of e.g., contaminants in shipping lanes need to consider hydrographic conditions, as stratification may alter the depth and spread of the wake, which in turn governs dilution. Finally, the frequent ship traffic in estuarine and coastal areas, calls for consideration of ship-induced turbulence when studying hydrographic processes.

The History of Sociological Research on Occupations and Professions in the USSR 1960-80s: Ideological Frameworks and Analytical Resources

The article analyzes of the content and context of research on occupations and professions in Soviet sociology from 1960 to the 1980s. It describes the key topics of observations of professional groups, gives definitions of occupations and professions in Soviet social sciences, and analyzes ideological and censorship restrictions for research and publishing. Sociology of occupations and professions as a separate disciplinary field appeared in Russia only in the late 1990s. Before this time, these topics were integrated into social structure and social stratification observations, research of the working class, intelligentsia, industrial sociology and sociology of organizations. From the 1960s Soviet sociologists searched for new explanatory models and they decided that socio-professional groups were the best criterion for a Soviet social structure description. During 1970-80s researchers of Soviet social structures debated about the place of professional groups. This article analyzes these and other features of sociology of occupations and professions in the USSR. The analysis is based on the bibliographical observations and interviews with Soviet sociologists. This project was supported by Science Foundation of NRU HSE.

Sensitivity Analysis on Lake Biwa under the A1B SRES climate change scenario using Biwa-3D Integrated Assessment Model:

Sensitivity analysis on lake temperature under the A1B SRES climate change scenario has been evaluated by coupling MRI-GCM with 20 km outputs and the Biwa-3D integrated assessment model. The non-hydrostatic 3D hydrodynamic model featuring Very Large Eddy Simulation (VLES) has been verified and compared with field observations in 2002 (the present-day year, PDY). A significant temperature increase in surface water, recording more than 34 degrees in the East Coast of the North Basin of the Lake Biwa, has been projected for the simulation for the very hot year (VHY), determined from comparison with MRI-GCM output for the year 2099, which may induce a catastrophic impact on lake water quality during the period. Weak stratification is predicted to start from March in VHY, compared with observations of stratification that doesn’t commence until after April in PDY. The thickness of the epilimnion which is around 15–20 m in PDY increases to 25–30 m in August in VHY due to a much higher atmospheric temperature. According to the model outputs, the vertical mixing may not always decrease due to the accumulated heat in the hypolimnion which has a higher temperature than the temperature during the winter. Accumulated heat in the hypolimnion may induce catastrophic degradation in the lake ecosystem.

Modes of Stratification in a Semi-enclosed Bay at the North Sea–Baltic Sea Transition

Conductivity, temperature and depth (CTD) measurements were recorded weekly at a fixed position in the shallow water of Århus Bay over a period of 1 year. Variations in stratification and salinity are described in this study. Outflow of low salinity water from the Baltic Sea, and an estuarine return flow of high salinity bottom waters originating in the North Sea were observed. Strong stratification occurs during spring, summer and late autumn, whereas stratification is weak or absent during winter. A stratification model in terms of the potential energy of the water column (φ) has been applied including wind, solar insolation, estuarine circulation and current terms. Observations of stratification are very well described by this model, although considerable differences were found to occur during a period of very strong stratification. The interface is placed at a water depth of about 8 m during spring and early summer, and at a depth of about 12 m during autumn. A comparison of frequently used stratification parameters shows a highly positive correlation between φ and the density difference between surface and bottom water. A positive correlation betweenφand Brunt–Väisälä frequency was also found in periods of stable oceanographic and meteorological conditions, whereas no correlation was found in periods of unstable conditions.

Observation of an anticyclonic vortex trapped above a seamount

Observations of stratification and currents in the area of the Great Meteor seamount indicate the existence of an anticyclonic vortex above the plateau of the seamount. The most likely mechanism for the generation of the vortex was found to be enhanced vertical mixing on the plateau due to vertical shear in tidal currents. The shear is caused by bottom friction and baroclinic modes.

Stratifications and Kinetic Changes in the Ingesta of the Bovine Rumen

Summary Samples of ingesta from the top and bottom of the rumen of three 2-year-old fistulated steers were taken at hourly intervals over a 12-hour period that included two feedings. The samples were analyzed for crude fiber, ash, ether extract, total nitrogen, ammonia, nonprotein nitrogen, water-soluble sugars, alcohol-soluble sugars, volatile fatty acids, and the digestion of cellulose in vitro. In all instances except alcohol-soluble sugars, significant or highly significant differences were observed between the top and bottom samples. Concentrations of all factors measured except ether-extract and the amount of cellulose digestion in vitro were significantly higher in top samples. These data together with the significant time fluctuations indicate that hay and grain particles follow distinctly different physical pathways in traversing the rumen. In a control experiment, duplicate samples were taken from both the top and the bottom of the rumen of a normal (unfistulated) mature Holstein cow by rumenotomy 3 hours after the morning feeding. These data show the same stratification as that seen in the samples from the steers. In additional analyses, pH and titratable alkalinity to pH 5.0 were significantly higher in bottom than in top samples. Observation of stratification in the rumen of the normal mature cow is evidence that the phenomenon is not an artifact resulting from fistulation.