Streaming potential near a hydrofracture

We suggest a mathematical model for the dynamics of the streaming potential near a hydrofracture of a seam after termination of water pumping into the fracture.     

Influence of the saffman force,lift force,and electric force on sand grain transport in a wind–sand flow

Quasi-horizontal trajectories of salting sand grains were found using high-speed video-recording in the desertified territory of the Astrakhan region. The sizes and displacement velocities of the saltating sand grains were determined. A piecewise logarithmic approximation of the wind profile in a quasi-stationary wind–sand flow is suggested, which is consistent with the data of observations and modeling. It was established that, in the regime of stationary saltation, the wind profile in the lower saltation layer of the wind–sand flow depends only slightly on the wind profile variations in the upper saltation layer. The vertical profiles of the horizontal wind component gradient in a quasi-stationary wind–sand flow were calculated and plotted. It was shown using high-speed video recording of the trajectory of a sand grain with an approximate diameter of 95 μm that the weightlessness condition in the desertified territory of the Astrakhan region in a stationary wind–sand flow is satisfied at a height of approximately 0.15 mm. The electric parameters of a wind–sand flow, which can provide for compensation of the force of gravity by the electric force, were estimated. In particular, if the specific charge of a sand grain is 100 μC/kg, the force of gravity applied to the sand grain can be compensated by the electric force if the vertical component of the electric field in a wind–sand flow reaches approximately 100 kV/m. It was shown that the quasi-horizontal transport of sand grains in the lower millimeter saltation layer observed in the desertified territory can be explained by the joint action of the aerodynamic drag, the force of gravity, the Saffman force, the lift force, and the electric force.     

Possible manifestations of underwater mud volcanoes based on results of sonar investigations in region of Taman Peninsula

This paper presents the results of three-dimensional acoustic seabed mapping in the region of the Taman Peninsula in the Black Sea using an interferometric side-scan sonar and an acoustic profiler. Mapping has revealed underwater objects identified as manifestations of underwater mud volcanism. Detailed analysis of sonar images of the relief and seabed profiles in the region of the objects has confirmed the original hypothesis.     

Modeling photosynthesis and the growth of marine phytoplankton

The paper analyzes the most popular models of photosynthesis and growth of marine phytoplankton in the literature and demonstrates their limitations. A new approach to modeling is proposed and used to obtain new models of marine phytoplankton photosynthesis and growth. An important feature of the proposed models is their ability to describe coupled multisubstrate cyclical interactions typical of biochemical and physiological processes. As a first approximation, the mathematical models are represented by equations of nonrectangular hyperbolas. The models describe the stoichiometry of extraction of elements from the medium, whatever the degree of their limitation, an important feature in describing biogeochemical cycles of elements. This stoichiometry is governed by measurable internal parameters of an organism (substrate parameters) and can be a key cause of stoichiometric formation of elements in the ambient medium, described, for example, by the Redfield ratio. The substrate constants are fundamental characteristics of the models, which form “automatically” in the construction of model equations in arbitrary units.     

Viruses,bacteria, and heterotrophic nanoflagellates in Laptev Sea plankton

The paper considers the concentrations and functional characteristics of viruses, bacteria, and heterotrophic nanoflagellates determined for the first time in the Laptev Sea in August-September, 2014. The abundance of bacteria, viruses, and heterotrophic nanoflagellates varied from 110.1 × 10³ to 828.4 × 10³ cells/mL, from 384.2 × 10³ to 2932.8 × 10³ particles/mL, and from 108 to 651 cells/mL, respectively. The daily bacterioplankton production varied from 4.2 × 10³ to 381.7 × 10³ cells/mL, with an average of 117.6 × 10³ cells/mL. Electron transmission microscopy has for the first time shown that the frequency of visibly infected bacterial cells varied from 0.2 to 2.0% (0.8% on average) of N_B. The average virus-induced mortality of bacteria was 6.3% of bacterioplankton production, with variations ranging from 1.4 to 16.9%. Grazing on bacteria by heterotrophic nanoflagellates contributed more to bacteria mortality than virus-induced bacterial lysis. By grazing on bacteria, heterotrophic nanoflagellates consumed large quantities of viruses located on the surface and inside bacterial cells.     

Sea surface wind and Sea ice in the Barents Sea using microwave sensing data from Meteor-M N1 and GCOM-W1 satellites in January–March 2013

Application of satellite passive microwave sensing for the retrieval of key climatic parameters in the Barents Sea is considered. Fields of surface wind, atmosphere water vapor content and cloud liquid water content were found from MTVZA-GY radiometer onboard the Meteor-M N1 satellite and AMSR2 onboard the GCOM-W1 satellite with the use of original algorithms. The fields are in a good agreement with the ancillary remote and in situ measurements, which follows from the analysis of the evolution of the extra tropical and polar cyclones and cold air outbreaks with storm winds leading to intense air-sea interaction, and the formation and drift of sea ice.     

Experimental studies of thermal radiation intensity dependence on near-water wind speed for rough sea surface

The results of in situ measurements of the characteristics of intrinsic microwave radiation from the sea surface are presented. The studies were carried out on the oceanographic platform of the Experimental Department of Marine Hydrophysical Institute during the summer–fall periods for 3 years, which made it possible to accumulate a significant amount of information on the change in the radiation intensity of under different meteorological conditions. Attention is primarily focused on the construction of wind-radiation dependences and their steepness analysis based on the measurement data obtained by a radiometer-polarimeter with a central frequency of received radiation equal to 37.7 GHz. The results are compared with the previous experimental studies and the model estimates of this effect.     

Retrospective analysis of seismic regime features before the Taiwan earthquakes of 1999 and 2002

The features of the seismic regime before the strongest earthquakes of Taiwan in the late 20th (Chi-Chi on September 21, 1999, M_w = 7.6) and the early 21st century (March 31, 2002, M_w = 7.4) are analyzed. Based on 1990–1999 and 1994–2002 data, respectively, retrospective analysis of three seismic regime parameters are studied: the total annual number of earthquakes N_Σ in the range of M_L = 2.5–5.5 and M_w = 3.0–7.0; the total annual quantity of released seismic energy ΣE, J; and angular coefficient b of earthquake recurrence graphs. Two explicit subperiods are revealed in the course of the seismic regime: quiescence in 1990–1996 before the Chi-Chi earthquake and in 1994–1997 before the March 2002 earthquake; in 1997–1999 and 1998–2002, respectively, seismic activation is observed. Due to the predominance of weak earthquakes during the Chi-Chi earthquake preparation, factor b appeared relatively higher (–1.16 on average); in contrast, before the March 2002 earthquake, due to the occurrence of foreshocks with M_w = 6.8–7.0, the factor b values appeared relatively lower (–0.55 and–0.74 for the quiescence and activation subperiods, respectively). Despite the fundamental difference in the seismotectonic situation between the domains where two mainshocks occurred and significantly difference energy ranges of the initial seismic events, the analysis results are similar for both earthquakes. In both cases, the mainshock occurred at the peak of released energy, which can be considered a coincidence. Solid verification of this positive tendency requires the accumulation of seismological statistics.     

Results of test experiment comparing measurement data of three adjacent ADCP bottom stations

The results of a test experiment comparing quasi-synchronous data of three adjacent acoustic Doppler current profilers (ADCPs) deployed on the shelf bottom of the Black Sea in September 2014 are considered. The direct aim of the experiment was quantitative comparison of data from different ADCPs placed in maximally similar conditions to simultaneously measure the sea current parameters at one geographic point. The goals and the scheme of the experiment, methods for processing the measurement results, main results, and their interpretations and analysis, including practical results and conclusions, are described.