Neutrino astrophysical potentialities of a large-mass modular detector based on large activated inorganic single crystals

The possibility of detecting neutrinos from the Sun and supernovae with detectors based on the nuclei ⁷Li, ¹⁹F, ¹²⁷I, and ²³Na is discussed.     

Climatic variability of the sub-surface sea temperatures in the Aegean-Black Sea system and relation to meteorological forcing

Non-smoothed yearly temperature records with minimal statistical uncertainties are constructed for winter and summer of the period 1950–2000 in two areas in the Aegean Sea, for the sub-surface layer of 80–120?m, and two areas in the Black Sea, for the sub-surface layer of sigma-theta isopycnals between 14.5 and 15.4. The specific areas are selected mostly because of the dense hydrographic-data coverage they have during the period 1950–2000. Two trend regimes appear in both Seas: a period of decreasing sea temperatures from the early/mid 1960s to the early/mid 1990s and an apparent warming afterwards. Trends in sea temperatures correlate with trends in the North Atlantic Oscillation (NAO) and partly the East Atlantic West Russian (EAWR) indexes, but the signs of NAO and/or EAWR cannot sufficiently justify the winter-to-winter temperature changes in the entire study area. In examining the wind flows in the sea-level-pressure maps for characteristic winters in which local peaks in the sea-temperature records occur, we identify particular sea-level-pressure structures that are not accounted for by the typical North-Atlantic or East Atlantic-West Russia positive or negative dipoles. In addition, there are winters when the Siberian High induces local maxima in sea-temperatures in the study area. A spectral-coherence analysis of the unfiltered winter sea-temperature and the corresponding teleconnection NAO/EAWR records, shows that common spectral and coherence peaks exist at ~5–6, ~9–10 and ~15–17?years.     

Metagalactic protons of ultra-high energies

The flux density of ultra-high-energy metagalactic protons generated by normal galaxies is calculated. Energetic losses of protons at interaction with the 2.7° relict and infrared radiations are revised. The time change of the energy of protons with different energies is estimated. The influence of fluctuations of energetic losses of protons on their spectrum is evaluated. The measured spectrum of cosmic rays can have a steepening (Δγ≈1.6) atE～3×10¹⁹eV instead of a sharp break expected previously.     

Akvazond moored automatic measuring system for vertical profiling of the marine medium

The design and application of the Akvazond moored automatic water profiling system is described. The system was developed at the Shirshov Institute of Oceanology of the Russian Academy of Sciences. The system is designed for multidisciplinary oceanological studies and environmental monitoring on the sea shelves and continental slopes. An autonomous carrier (marine elevator) for different oceanic measuring equipment was developed for the first time in the practice of Russian oceanography. It is a carrier, for example, for an acoustic Doppler current meter, a CTD-profiler, a sensor of dissolved oxygen, a fluorometer, a turbidity meter, etc. The Akvazond system has an energy resource sufficient for profiling the water column in the programming regime for up to several months. The total length of the vertical displacement of the system at a nominal capacity of the power supply reaches 200 km. The main results of the field tests of the Akvazond and preliminary scientific results of its application are presented on the basis of the results of the Black Sea-2006 expedition.     

Variability of currents in the coastal zone of the Black Sea from long-term measurements with a bottom mounted ADCP

The results of long-term measurements (16 months) of the current??s velocity in the Black Sea coastal zone near Golubaya Bukhta (Blue Bay) by a bottom mounted acoustic Doppler current profiler (ADCP) are presented and discussed. It was found that the alongshore component of the current dominates and its absolute value is an order of magnitude larger than the absolute value of the normal to the shore component. The annual average value of the alongshore current??s velocity is close to zero. A well pronounced oscillatory mode of the alongshore current??s velocity is revealed. This mode is characterized by quasi-periodic changes in the direction of the alongshore current. The maximal amplitudes of the unidirectional alongshore current??s velocity are observed with a time scale from several hours to several days.     

Influence of the dynamics of currents on the hydrophysical structure of the waters and the vertical exchange in the active layer of the Black Sea

An analysis of the data of measurements of the fine structure and microstructure fluctuations of hydrophysical fields in the upper 200-m layer of the Black Sea carried out using CTD profilers and a Baklan free falling microstructure and turbulence profiler revealed the existence of a positive correlation between the intensity of the fine structure and microstructure fluctuations and the dynamics of the currents. On the other hand, the level of the fine structure and microstructure fluctuations reflects the rate of the vertical turbulent exchange. It was shown that, in the case of the absence of the Black Sea Rim Current (BSRC) jet or clearly manifested mesoscale eddy structures, the vertical turbulent exchange in the pycnocline is weak, while, in the opposite case, it is stronger. The results obtained support the supposition that the interbasin dynamics play an important role in the maintenance of the rate of small-scale mixing in the pycnocline and halocline and provide the vertical transport of dissolved oxygen from the cold intermediate layer into the deeper layers of the sea.     

Autonomous system for vertical profiling of the marine environment at a moored station

This paper presents new results of the research and development project on the moored profiler Aqualog aimed at multidisciplinary studies and ecological monitoring of the marine environment. The data on the profiler’s operation are summarized based upon the field experiments in the northeastern Black Sea in 2011. An important scientific result obtained by using the profiler during the experiments was the discovery of the countercurrent below the Black Sea Rim Current in the layer between the 500 m and 900 m depth.     

Physical mechanisms of submesoscale eddies generation: evidences from laboratory modeling and satellite data in the Black Sea

Ocean Dynamics - The observed evidence of the implementation of three different mechanisms of the submesoscale eddies generation in the Black Sea previously studied by the field research and...     

Gravity current down a steeply inclined slope in a rotating fluid

The sinking of dense water down a steep continental slope is studied using laboratory experiments, theoretical analysis and numerical simulation. The experiments were made in a rotating tank containing a solid cone mounted on the tank floor and originally filled with water of constant density. A bottom gravity current was produced by injecting more dense coloured water at the top of the cone. The dense water plume propagated from the source down the inclined cone wall and formed a bottom front separating the dense and light fluids. The location of the bottom front was measured as a function of time for various experimental parameters. In the majority of runs a stable axisymmetric flow was observed. In certain experiments, the bottom layer became unstable and was broken into a system of frontal waves which propagated down the slope. The fluid dynamics theory was developed for a strongly non-linear gravity current forming a near-bottom density front. The theory takes into account both bottom and interfacial friction as well as deviation of pressure from the hydrostatic formula in the case of noticeable vertical velocities. Analytical and numerical solutions were found for the initial (t < 1/f), intermediate (t 1/f), and main (t 1/f) stages, where f is the Coriolis parameter. The model results show that during the initial stage non-linear inertial oscillations are developed. During the main stage, the gravity current is concentrated in the bottom layer which has a thickness of the order of the Ekman scale. The numerical solutions are close to the same analytical one. Stability analysis shows that the instability threshold depends mainly on the Froude number and does not depend on the Ekman number. The results of laboratory experiments confirm the similarity properties of the bottom front propagation and agree well with the theoretical predictions.