Vertical Structure of Currents in Northern Black Sea,October 2016

The paper presents the results of an analysis of hydrological data obtained on cruise 89 of the R/V Professor Vodyanitskii from September 30 through October 19, 2016, in the central area of the northern Black Sea. Currents were measured using a lowered acoustic Doppler current profiler (LADCP) to a depth of 350 m. Examples of the current velocity profiles and conditional density at individual stations are presented. The averaged characteristics of the vertical current structure in the seasonal and permanent pycnoclines are discussed. The isopycnally averaged kinetic energy (KE) demonstrates an almost linear dependence on the conditional density (σ_θ). In the seasonal pycnocline, EK = 0.2–0.013σ_θ; in the permanent pycnocline, EK = 0.12–0.007σ_θ. An interpretation is given for the variability of the kinetic energy with depth. It is shown that the maxima of the averaged vertical shear profile correspond to the occurrence depth of the seasonal and permanent pycnoclines. The mean Richardson number has a value of ~10 in the upper sea layer and decreases with depth, assuming a value of ~3 at the 300 m horizon. The estimate for the vertical turbulent diffusion coefficient from the simplified model shows its increase with depth.     

Budget and Fluxes of Particulate Organic Carbon and Nitrogen According to the Data on Their Vertical Distribution in the Deep Part of the Black Sea

On the basis of the analysis of the many-year data on the vertical distributions of particulate organic carbon and nitrogen, we compute their annual average amounts for three typical layers of water in the deep part of the Black Sea: for a layer located above the oxycline and characterized by the formation of new portions of particulate organic matter in the course of photosynthesis, inside the oxycline, where the major part of oxygen is consumed and the major part of the flux of particulate organic matter is oxidized, and for the upper part of the anoxic zone characterized by the most active microbiological processes of oxidation of the organic substances and production of sulfides. The available literature data on sedimentation traps are used to study the downward annual average fluxes of particulate organic matter from the euphotic zone into the oxycline and into the anaerobic zone. The seasonal variability of the amounts and fluxes of particulate carbon and nitrogen is revealed.     

Analysis of the Variability of the Optical Properties of Water in the Black Sea in Summer 1998 According to the Data of a SeaWiFS Satellite Instrument

We study examples of surveys of the Black Sea performed with the help of a SeaWiFS satellite instrument. It is shown that the results of measurements carried out in spectral channels of 510 and 555nm give information on the basic specific features of the space and time variability of the characteristics of absorption and scattering of light in seawater. The use of a spectral channel of 412nm is inefficient due to the low reliability of the results of the procedure of atmospheric correction performed according to standard algorithms. The results of model calculations demonstrate that the predominant contribution to the absorption of light in the Black Sea in summer is made by the yellow substance.     

Circulation of Waters in the Northwestern Part of the Bering Sea According to Satellite Data

Izvestiya, Atmospheric and Oceanic Physics - A study of water circulation in the northwestern part of the Bering Sea using AVISO satellite data on velocities of geostrophic currents from 2002 to...     

Currents in the Bransfield Strait Based on Geostrophic Calculations and Data of Instrumental Measurements

Izvestiya, Atmospheric and Oceanic Physics - In January 2022, several sections were made across the Bransfield Strait during an Antarctic expedition on the R/V Akademik Mstislav Keldysh....     

Mean Dynamic Topography and Geostrophic Surface Currents in the Fram Strait Derived from Geodetic Data

Two mean dynamic topography (MDT) fields are determined in the Fram Strait between Svalbard and Greenland. New airborne gravity anomalies, older data, and two different mean sea surface (MSS) fields are combined using the least squares collocation (LSC) technique. The results are compared to an oceanographic MDT model and two synthetic MDT fields. The same main currents are seen in all fields. Additionally, smaller scale features are revealed in the new MDT fields. Geostrophic surface currents derived from the MDT models are compared to moorings and Lagrangian drifters. The agreement is desultory. The oceanographic data are an inadequate basis of comparison due to data gaps. Nevertheless, it is the only one available.     

Advection Mechanism of Replenishment and Refreshment of the Cold Intermediate Layer According to the Results of Numerical Simulation of Currents in the Black Sea

We present the results of analysis of the advection mechanism of replenishment and refreshment of the cold intermediate layer in the Black Sea. The analysis is based on the investigation of the fields of temperature, salinity, density, currents, and the coefficient of vertical turbulent diffusion obtained in the course of prognostic calculations according to the three-dimensional complete model with seasonally variable external fields in boundary conditions. It is discovered that, parallel with winter convection, the cold intermediate layer in the central part of the sea is also replenished and refreshed as a result of the transportation of cold waters formed in the northwest part of the sea by currents.__________Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 17–30, November–December, 2004.     

Effects of Friction and Buoyancy Diffusion on the Dynamics of Geostrophic Oceanic Currents with a Linear Vertical Velocity Profile

Izvestiya, Atmospheric and Oceanic Physics - A spectral problem of the Orr–Sommerfeld type is considered to describe unstable disturbances of oceanic geostrophic currents with a linear...     

Thermohaline Anomalies and Fronts in the Black Sea and Their Relationship with the Vertical Fine Structure

Oceanology - Thermohaline anomalies in the upper 300-m layer at stations of the so-called “hundred-mile” ship sections over the line “coastal zone of Gelendzhik–central part...     

Hydrooptical Characteristics of Subsatellite Test Ranges in the Mediterranean and Black Seas According to the Data of Investigations Performed by the R/V Gorizont in 1998

Hydrooptical investigations were performed for three subsatellite test ranges located near the Rhodes Island in the Levant Sea, near Dardanelles in the north part of the Aegean Sea, and near the Crimean Peninsula in the northwest part of the Black Sea. In the course of observations, we measured the beam attenuation coefficient, the depth of visibility of the Secchi disk, and the color of water. These data are used to characterize the space and time variability of the optical properties of water in the investigated regions.     

Vertical mesostructure of deep waters in the Black Sea

Studies of mesoscaleT, S characteristics of deep waters in the Black Sea carried out during 1978–1988 are generalized. Transformed lower Bosphorus waters are spread in the layer from 400 m to the bottom following density isosurfaces corresponding to this water. This is the way that interlayers ofT, S inversions are formed; their vertical thickness reaches 100–200 m in the Anatolian flow. The streamwise decrease of theT, S maxima and the location of isotherms in the cross-sections of these tongues permit the estimation of the order of the values of the coefficients of the vertical and horizontal turbulent diffusion.Translated by Mikhail M. Trufanov.     

Evolution of the Cold Intermediate Layer in the Black Sea According to the Results of Assimilation of Climatic Data in the Model

We present the results of analysis of the seasonal variability of the climatic cold intermediate layer based on a complex approach with the use of series of successive changes in the hydrophysical parameters computed according to the model with assimilation of the climatic fields of temperature and salinity. We analyze some mechanisms of formation of the cold intermediate layer. It is discovered that the layer of cold waters, which is continuous after regeneration and transformation in the entire deep-water area of the sea, becomes discontinuous at the end of the year (October–November). One of the possible mechanisms responsible for the appearance of discontinuities is discussed.     

渤海及黄海北部的风海流数值计算及余流计算

依据黄渤海实测风的资料对渤海及北黄海进行了月平均风海流数值计算。计算表明 ,1月份在西北风的作用下 ,在渤海出现 1个逆时针旋转的环流 ,在辽东湾北部及黄海北部出现 1个顺时针旋转的环流 ,渤海海峡的海流北进南出。 7月份在南风和东南风的作用下 ,风海流的变化形式与 1月份大致相反 ,海峡处呈南进北出的形式。对渤海中部某点 1年的潮流资料通过低通滤波的方法计算逐时的余流值 ,得到该点 1年内表层最大的实测余流为 31.9cm/ s,全年 90 %多的时间内表层余流小于 10 cm/ s。对辽东湾北部某点和渤海湾西南部某点数月潮流资料也进行了低通滤波 ,并将得到的逐时余流与同步风作了比较。依据该 2点风和余流的关系以及黄海北部 6个点风和余流的关系验证了风海流数值计算的结果 ,表明在这些点上实测与计算结果拟合良好     

Changes in Temperature,Sea Level,and Geostrophic Currents in the Northwestern Pacific Ocean and Southwestern Bering Sea under the Influence of the Nodal Tide

Izvestiya, Atmospheric and Oceanic Physics - An analysis of satellite data and Argo float data has shown the variability in the sea surface temperature (SST), sea level, and geostrophic currents in...     

Determination of Mesoscale Surface Currents in Shallow-Water Regions According to the Data of High-Frequency Radar Measurements

We propose a new method for the evaluation of the velocities of surface currents according to the data of measurements carried out by using high-frequency land-based radars. The method is based on the representation of the velocity fields via two scalar potentials, expansion of these potentials in series in basis functions, and determination of the coefficients of expansion according to the data of radar measurements as solutions of the corresponding variational problems. The errors of the procedure of determination of the coefficients of expansion are removed by using a special regularization procedure based on information theory. The proposed method enables one to fill gaps in the space and time series of radar measurements. We illustrate the method by an example of numerical analysis of mesoscale and submesoscale (10–50 km) surface currents in the Monterey Bay (California, USA) performed on the basis of the data of radar measurements carried out in August 1994. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 24–36, March–April, 2005.     

Comprehensive studies in the Black Sea and the Sea of Azov in the Summer of 2012

The shelf zones of the Black Sea, Taman Bay, and the Sea of Azov are currently subjected to gross load related to the impact of invasive species, large-scale construction activities near the coast, intensive recreation activity, water pollution in large cities and ports, active navigation, unreasonable coastal arrangement, and dam construction. Another factor substantially affecting the composition of bottom sediments and, thus, the benthos environment is the terrigenous material carried by rivers in the course of catastrophic overflows. An example is the Kubansk flood in 2012, which significantly affected the sea coast near Novorossiysk, Gelendzhik, and Divnomorsk. The intensive onshore dumping results in the delivery of abundant allochthonous material, bottom silting causing changes in the dominants in the benthos associations, a decrease in the photic layer and the death of the phytobenthos, and also debris formation at the bottom. Debris can play the role of artificial reefs contributory for the formation of periphytic biocoenoses.     

Description of the Perturbations of Oceanic Geostrophic Currents with Linear Vertical Velocity Shear Taking into Account Friction and Diffusion of Density

Izvestiya, Atmospheric and Oceanic Physics - Abstract—A spectral problem of the Orr–Sommerfeld type for describing stable and unstable perturbations of oceanic geostrophic flows with...     

Vertical turbulent exchange in the Black Sea pycnocline and its relation to water dynamics

Estimates of vertical turbulent diffusion coefficient (K _t ) in the Black Sea pycnohalocline have been obtained from data of simultaneous observations of seawater temperature, salinity, density, and horizontal current velocity, obtained in the northeastern part of the Black Sea during 2013–2014 with a moored Aqualog profiler. A Munk and Andersson (1948) type parameterization, adapted for the Black Sea environment, is proposed for calculating K _t . Strong short-period (several days) variability of turbulent exchange is revealed, induced by vertical shear variations of the current velocity.     

Vertical distribution of the hydrogen sulphide sources in the Black Sea

Data on the diffusion coefficientK _zand the concentration of H₂S in the Black Sea are used to compute the depth distribution of the vertical flux, and the intensity of the H₂S sources and sinks. On average, the total production of H₂S in the Black Sea reaches 37×10⁶ t/year. The main bulk of H₂S is produced not at the bottom, but in the layer of 450–1300 m. Destruction of H₂S prevails above the 400 m layer. Dissolved oxygen penetrating the H₂S zone can oxidize only half of the hydrogen sulphide produced in the sea.Translated by Mikhail M. Trufanov.     

Vertical Migration of Sound Scatterers in the Southern Yellow Sea in Summer

Acoustic volume backscattering strength data were collected and Conductivity Temperature Depth (CTD) measur e m e n t s were conducted in the southern Yellow Sea in summer 2005 and 2006. The high temporal and vertical resolution acoustic data measured with a 307 kHz Acoustic Doppler Current Profiler (ADCP) and a 250 kHz acoustic Doppler profile (ADP) had dominant diel variation, which resulted from vertical migration of sound scatterers. Some scatterers congregating in the bottom layer in the daytime migrated upward at dusk, and migrated downward into the bottom layer at dawn. The migration speeds were estimated. More than 33 days data show that the diel migration varies with time. The feature of migration measured with ADCP and ADP is consistent to some extent with what is described in the study on vertical migration of zooplankton in the southern Yellow Sea with conventional net samples.