Field measurements of the vertical shears for a drift current

We describe the procedure of field experiments aimed at measuring the vertical profiles of the vectors of a drift current with the help of quasi-Lagrangian drifters. We present the data on the vertical shears of the current at depths of 0.5–5 m obtained under the conditions of neutral stratification in the upper 5-m layer of the sea in the presence of weak and moderate winds. The correspondence of the obtained data to the concept according to which the subsurface layer of the sea is regarded as a near-wall turbulent layer with Ekman current located below is analyzed. A conclusion is made that the results of measurements correspond, on the average, to the classical concepts demonstrating both the region of logarithmic sublayer and its transition into the Ekman spiral. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 32–44, January–February, 2007.     

Study of nonlinear currents induced by coincident surface waves in liquid

This is an experimental study of the mixing induced by coincident surface waves in a liquid. The main mechanism leading to the emergence of mixing was shown to be the middle currents generated by coincident waves. The regime of these currents strongly depends on the amplitude of surface waves. For waves of near-critical amplitudes, an intense turbulization of middle currents is observed. Patterns of the velocity field were obtained using the Particle Imaging Velocimetry (PIV) technique for different amplitudes of surface waves. The results obtained can be used to estimate mixing in the near-surface oceanic layer.     

Boltzmann statistical theory and asymptotics of the temperature distribution of spontaneous jets in the convective atmospheric surface layer

An ensemble of convective thermals is distinguished from the surface layer of penetrative turbulent convection over a heated horizontally uniform surface. A statistical model of the ensemble of convective thermals is developed that uses the idea of entropy in the Boltzmann-Jaynes form. The distribution of thermals by potential energies is shown to display an entropy maximum. On the basis of the Boltzmann distribution by potential energies, the temperature distribution of spontaneous jets is obtained and found to be consistent with known experimental data.     

Mineralogical-geochemical features of sulfide ores from the Broken Spur hydrothermal vent field

A representative collection of hydrothermal sediments was sampled practically from all the hydrothermal mounds of the Broken Spur hydrothermal vent field from the Mir manned submersibles during three cruises of R/V Akademik Mstislav Keldysh. Mineral associations characteristic of different morphological types of sulfide ores from hydrothermal pipes, plates, and diffusers are assessed. Particular attention is paid to the distribution of minor elements and their distribution patterns determined by the mineralogical zonation. The measured isotopic value of the sulfur in the sulfide minerals appeared to vary from 0.4 to 5.2‰, which indicates their similarity with the ores from the Snake Pit vent field and is related to the dilution of hot ore-bearing solutions by seawater and reduction of the water sulfate ions to H₂S with a heavy isotopic composition.     

Aerosol and radiation characteristics of the atmosphere during forest and peat fires in 1972, 2002, and 2010 in the region of Moscow

Estimates of some aerosol and radiation characteristics of the atmosphere in the summer of 2010 are obtained according to the results of the measurements made at the Meteorological Observatory (MO) at Moscow State University and are compared with the results of the measurements performed in 2002 and 1972 during the forest and peat fires. In contrast to 1972 and 2002, the period under study in 2010 is characterized by a greater frequency of the highest class of fire danger according to Nesterov, higher aerosol optical depths of the atmosphere up to 4.6, and a more significant weakening of solar radiation in different spectrum regions. In 2010 the smoke aerosol caused losses of the total shortwave radiation of 33%, visible radiation of 39%, ultraviolet radiation of 300–380 nm of 51%, and erythemal radiation of 63%. At the same time, an increase in the downward long-wave radiation to 40–50 W/m² under extreme aerosol optical depths is recorded.     

On the origin of phosphorites from Christmas Island in the Indian Ocean

A detailed investigation of microstructures of the phosphorites from Christmas Island under a scanning electron microscope coupled with an analysis of their chemical composition revealed that both their structure and composition are quite similar to those of the granular and microgranular phosphorites on present-day continents, as well as those of the phosphorites on some of the Pacific guyots. Their composition, together with their geological position and interrelationships with the surrounding rocks, proves that the ornitogenic hypothesis based on the presumed guano accumulation followed by its transformation into phosphatic rock is not compatible with the field observations. Meanwhile, the problem of the source of the Fe and Mn impregnation in the phosphorites remains unresolved and needs further investigations.     

The problem of the 11th marine isotope stage from the viewpoint of the new conception of the orbital theory of the paleoclimate

It is shown that the so-called MIS-11 problem is not a problem of the Milankovitch theory but is a problem of his followers. The existence of this problem points out the drawbacks of the corresponding theoretical notions that associate the insolation variations with the global climate changes in the Pleistocene. The conclusion is reached that the MIS 11 problem is a particular case of the more common problem of the disparity of the orbital induced insolation variations and global climate changes in geological time intervals.     

The coastal profile in the eastern Gulf of Finland: The results of a survey and the reconstruction of the evolution in the Late Holocene

The studies carried out by the Karpinskii All-Russia Research Institute of Geology using side-scan profiling, echo sounding, and surface sediment sampling allowed revealing the detailed structure of the underwater coastal slope in the eastern Gulf of Finland. In particular, a submarine sand terrace was found at depths of 4–5 m. An attempt at the reconstruction of the coastal evolution over the period of the Late Holocene was made using mathematical modeling in order to explain the observed morphology of the submarine coastal slope. The key assumption of the concept suggested is that, at the earlier stage, the tectonic processes played the main role, while, at the later stage, the sea-level changes were of greater importance. The tectonic block comprising the investigated area of the Gulf of Finland at first rapidly increased and then it stabilized and was influenced by the sea level’s rise. These processes resulted in the formation of a series of terraces. The earlier of those are now located on dry land, while the later terraces are observed on the submarine slope. Within the concept proposed, the coastal evolution in the Late Holocene appears as a process of the gradual erosion of the above-water terraces and the formation of new underwater terraces. During the transgressive phases, the rate of the coast’s recession reached 0.5 m year⁻¹, while decreasing by a factor of two during the intermediate stages. The submarine terrace developed over the period of 3.2–1.2 thousand years ago, and it extended in equal measure due to the coast’s recession and the material’s accumulation near its external edge. During that period, the coast retreated by approximately 500 m, while the average accumulation rate could have been as high as 0.7 m³ m⁻¹ year⁻¹.     

The assessment of the age of scleractinian coral species (Anthozoa: Scleractinia) based on the temperature ranges of their habitat

Until now, the age of deep-water scleractinians was determined based only on rare finds of these corals in terrestrial sequences, which constitute <10% of their known diversity. Inasmuch as most of the non-zooxanthellate coral species dwell in the ocean beyond the shelf zone (up to the abyssal depths) and their fossil remains are missing from terrestrial sections, we propose a new approach to the assessment of their age based on paleoecological features: the seawater temperatures in the geological past and the habitat temperature ranges established for 53 coral species. The study confirmed our previous assumption concerning the very young age of the deep-water fauna.