Statistical study of visual binaries

In this paper, some statistical distributions of wide pairs included in the Washington Double Star Catalog are investigated. Frequency distributions and testing hypothesis are derived for some basic parameters of visual binaries. It was found that the magnitude difference is distributed exponentially, which means that the majority of the components of the selected systems are of the same spectral type. The distribution of mass ratios is concentrated at about 0.7 which agrees with Salpeter mass function. The distribution of the linear separation appears to be exponential which contradicts previous studies for close binaries.     

Thermodynamic characteristics of water in natural water bodies with a high mineralization

To adequately describe the hydrophysical processes in water bodies with a high mineralization, it is necessary to take into account the dependence that the thermodynamic characteristics of water have on the amount of salts contained in it. This work investigates some widely known formulas for calculating a number of thermodynamic parameters of mineralized water. The density, freezing temperature, specific heat of evaporation, and relative pressure of saturated vapor over the surface are considered. The possibilities of using these formulas when modeling hydrophysical processes in water bodies with salinity in the range of 0–250 pro mille are analyzed. It is shown that the formulas under consideration should be used when the salinity does not exceed 100 pro mille. If the mineralization is higher, it is necessary to elaborate more suitable formulas on the basis of an approximation of in situ data or data from handbooks.     

Studies of temperature effects of dust storms

We studied the temperature variations of the lower air layer caused by dust content using a dust storm in Dushanbe in November 2007 as an example. Quantitative estimates of air cooling and a decrease in the diurnal temperature difference due to a diminishing horizontal visibility range are given. Observations of air temperature variations due to the dust content of the atmosphere in an arid zone are presented. The critical value of aerosol concentration for toggling between the greenhouse and antigreenhouse effects is determined. The long-term effect of dust aerosol on climate is analyzed.     

Bottom fauna associated with <Emphasis Type="Italic">Bathymodiolus azoricus</Emphasis> (Mytilidae) mussel beds in the hydrothermal fields of the Mid-Atlantic Ridge

The structure of the assemblages associated with the mussel aggregations of Bathymodiolus azoricus was investigated. The mussel beds were found on the hydrothermal vent fields on the Mid-Atlantic Ridge (the Menez Gwen, Lucky Strike, and Rainbow areas) at the depths of 850–2400 m. The community structure of the mussel bed assemblages varied between the studied areas. Large number of species was unique to Menez Gwen mussel beds; the most observed taxa were not specialized hydrothermal species. All the other, nonunique species were found for the Lucky Strike region. The lowest mussel assemblage structure evenness was observed in the shallowest area, the Menez Gwen area (850 m depth). We assume that two types of mussel assemblages—nematode-dominated and copepod-dominated ones—exist in the Lucky Strike field. The assemblages of B. azoricus differ significantly from the assemblages of B. thermophilus inhabiting the Pacific hydrothermal vents.     

On features of structure of bottom gravity current frontal zone

The results of qualitative laboratory and numerical experiments on two-dimensional non-linear model are described, aiming at an investigation of the structure of the front of bottom gravity current. Non-coincidence of frontal interfaces in density and velocity fields within the bottom gravity current leading (frontal) part is stated on the base of comparative analysis of numerical and laboratory experiments. This fact is experimentally confirmed by field example of marine water inflow into a brackish lagoon. The density gradient along the stream line is shown to be an additional effective criterion for the localization of the frontal zone.     

A nonlinear PDE formulation for offshore vessel pipeline installation

In this paper a nonlinear dynamic PDE formulation for a pipe string suspended from a pipelay vessel to the seabed in a pipelay operation is developed. This model extends a three-dimensional beam model capable of undergoing finite extension, shearing, twist and bending, to apply for marine applications by adding the effects of restoring forces, hydrodynamic drag and seabed interaction. The model is validated against the natural catenary equation and the FEM code RIFLEX. The model is extended to include the pipelay vessel dynamics by applying a potential theory formulation of a surface vessel, suited for dynamic positioning and low speed maneuvering, as a boundary condition for the PDE. This system is found to be input-output passive and stable. Pipeline installation applications where the presented model is suited are e.g., analysis and simulation of the installation operation, operability analysis, hardware-in-the-loop (HIL) testing for vessel control systems, and automation of the pipelay operation.     

Stratigraphy and formation conditions of the sedimentary cover in the Sea of Japan near the Bogorov Rise

The results of the complex study of the sedimentary cover (continuous seismic profiling and diatom analysis) in the northeastern part of the Sea of Japan, including the Bogorov Rise, the adjacent part of the Japan Basin, and the continental slope, are presented. Two varied-age complexes were distinguished in the sedimentary cover of Primorye’s continental slope, namely, the Middle Miocene and Late Miocene-Pleistocene; these complexes were formed in a stable tectonic environment with no significant vertical movements. The depression in the acoustic basement is located along the continental slope and it is divided from the Japan Basin by a group of volcanic structures, the most uplifted part of which forms the Bogorov Rise. The depression was formed, probably, before the Middle Miocene. In the Middle Miocene, the Bogorov Rise was already at the depths close to the modern ones. In the sedimentary cover near the Bogorov Rise, buried zones were found, which probably were channels for gas transportation in the pre-Pleistocene. Deformations of sediments that occurred in the beginning of the Pleistocene are established in the basin.     

Effect of atmospheric CO2 and solar activity on wind regime and water column stability in the major global upwelling areas

It is not clear whether global warming will favour or reduce global ocean phytoplankton productivity in coastal areas. Moreover, the relative contributions made by natural and/or anthropogenic factors to possible changes in phytoplankton productivity are not clear. As the relationship between primary production and alongshore wind forcing is well established for the Eastern Boundary Current (EBC) ecosystems, our aim is to determine whether the changes experienced over the last five decades (1958–2007) in atmospheric CO₂ and solar activity have been able to affect the wind regime and water column stability in the most biologically productive upwelling areas of California, Canary, Humboldt and Benguela. We approached the work by statistically studying the effect of solar activity and atmospheric CO₂ on surface alongshore wind stress and on water column stability. There was an increasing trend in wind stress and water column stability in all the upwelling areas over the period studied (with the single exception of stability in the California EBC system). The analysis of detrended series evidenced significant relationships between atmospheric CO₂ concentration and wind stress and water column stability in the coastal upwelling areas investigated. In addition, wind stress and stability data were found to be consistent, with negative linear relationships between wind stress and CO₂ in most of the sites in the Benguela, Canary and Humboldt regions associated, as expected, to positive relationships when water column stability is used as regressand. The results of the present study suggest that greenhouse gas forcing, independent of its well known general increasing trend, was able to decrease wind stress intensity and increase water column stability for the period 1958 to present in most of the sites of the four Eastern Boundary Ecosystems studied, with the one exception of the California region. Conversely, the impact of solar activity appeared to be quite low compared to the greenhouse gas forcing.     

Calibration and use of continuous heat-type automated seepage meters for submarine groundwater discharge measurements

Submarine groundwater discharge (SGD) assessments were conducted both in the laboratory and at a field site in the northeastern Gulf of Mexico, using a continuous heat-type automated seepage meter (seepmeter). The functioning of the seepmeter is based on measurements of a temperature gradient in the water between downstream and upstream positions in its flow pipe. The device has the potential of providing long-term, high-resolution measurements of SGD. Using a simple inexpensive laboratory set-up, we have shown that connecting an extension cable to the seepmeter has a negligible effect on its measuring capability. Similarly, the observed influence of very low temperature (≤3 °C) on seepmeter measurements can be accounted for by conducting calibrations at such temperatures prior to field deployments. Compared to manual volumetric measurements, calibration experiments showed that at higher water flow rates (>28 cm day⁻¹ or cm³ cm⁻² day⁻¹) an analog flowmeter overestimated flow rates by ≥7%. This was apparently due to flow resistance, turbulence and formation of air bubbles in the seepmeter water flow tubes. Salinity had no significant effect on the performance of the seepmeter. Calibration results from fresh water and sea water showed close agreement at a 95% confidence level significance between the data sets from the two media (R² = 0.98). Comparatively, the seepmeter SGD measurements provided data that are comparable to manually-operated seepage meters, the radon geochemical tracer approach, and an electromagnetic (EM) seepage meter.