Spatial structure of the southern polar frontal zone of the Atlantic Ocean

On the basis of the many-year-average seasonal data array of temperature and salinity presented on a scale of one-degree averaging, by using a special quantitative criterion, we reveal a climatic frontal zone and determine both its physical and hydrological characteristics (such as the length width, and thickness of the frontal layer and the temperature, salinity, and density gradients) and its geographic coordinates. The many-year average seasonal variability of these characteristics is analyzed. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Space structure of the climatic discharge frontal zone of the Amazon

On the basis of the data array of many-year average seasonal values of temperature and salinity represented for a one-degree scale of averaging, by using a quantitative criterion, we select the climatic discharge frontal zone of the Amazon, determine its physical and hydrological characteristics: length, width, thickness of the frontal layer, temperature, salinity, and density gradients, and specify its geographical coordinates. We also describe the many-year average interseasonal variability of these characteristics. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Vertical Thermohaline Structure,Water Masses,and Large-Scale Fronts in the Southwest Atlantic and Neighboring Antarctic Water Areas

The vertical profiles of temperature and salinity are classified by using the contemporary array of actual and monthly average archive oceanographic data. A scheme of decomposition of the investigated water area into zones according to the typical features of vertical stratification of the thermohaline field is proposed. The criterion of maximum of the horizontal temperature and salinity gradients is used to select and map the principal large-scale frontal boundaries. The parameters of fronts and some regularities of their seasonal variability are described and the data on water masses interacting in the analyzed system of fronts are presented.     

Physical and hydrological characteristics of climatic frontal zones in the Tropical Atlantic

Climatic frontal zones are selected in the thermohaline fields of the Tropical Atlantic by analyzing the many-year-average seasonal database reduced to the nodes of a one-degree grid. We determine physical characteristics of the frontal zones, study their spatial and temporal variability, and reveal basic regularities of the appearance of frontal zones in the fields of thermohaline characteristics. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Reconstruction of the seasonal climate of the Black Sea on the basis of available hydrological data

We analyze the seasonal variability of the climatic hydrophysical fields of the Black Sea reporduced in three numerical experiments carried out according to the model of circulation. The numerical predictions are performed for a period of 12.5 yr on the basis of the hydrological data accumulated in 1983–1995. The monthly average climatic fields of the current speed are reconstructed according to the data on the climatic fields of temperature and salinity by the method of hydrodynamic adaptation (standard). It is shown that, in prognostic calculations, the seasonal variability of temperature and salinity is qualitatively close to the “standard” dependence. At the same time, the quantitative difference between the climatic behavior of the model and the standard dependence may be significant. The annual cycle of the currents is characterized by the intensification of the Main Black-Sea Current in winter. The structure of the hydrophysical fields of the sea in the model becomes much more realistic if it is based on the actual hydrological data. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Experimental evaluation of the characteristics of vertical mixing in an oceanic thermohalocline on the basis of fine-structure spectra of advection, salt fingers, and small-scale internal waves

We describe a differential approach to the spectral composition of thin thermohaline inhomogeneities in the ocean depending on the mechanisms responsible for their generation and demonstrate the possibilities of this approach in getting realistic hydrophysical results. The statistical classification of fine-structure fluctuations according to their origin is performed on the basis of the joint analysis of the temperature, salinity, and density spectra computed in a section of the vertical profile where the variation of mean gradients of all three parameters is insignificant. On the basis of the constructed mean spectrum of wave elevations, we estimate the dissipative characteristics of the convection of salt fingers and small-scale internal waves. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Investigation of Frontal Zones in the Karkinitskii Bay

On the basis of the data from the databank of the Marine Hydrophysical Institute of the Ukrainian National Academy of Sciences and the data of regional marine hydrometeorological stations, we present the characteristics of the seasonal variability of temperature and salinity frontal zones and background gradients in waters of the Karkinitskii Bay. We determine the locations of the frontal zones, the values of their gradients, horizontal scales, repetition, connection with weather conditions, inflow, and direction of propagation of salt and freshened waters in the bay in different seasons of the year. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 30–42, July–August, 2005.     

North Brazil Current: Variability, stability and transport of waters

On the basis of the data of thein situ measurements of current velocities and other basic hydrophysical parameters (temperature and salinity) performed in the course of Cruise 41 of the R/VAkademik Vernadsky, we analyze the variability and stability of the North Brazil Current in winter. We also study the possibility of the influence of the baroclinic component of the horizontal drop of hydrostatic pressure on the vertical profile of the current velocity and estimate the intensity of the transport of waters. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Convection of salt fingers in theC-SALT region

We study possible mechanisms of mixing in the northwest part of the Tropical Atlantic (C-SALT) and show that homogeneous layers in the staircase structure can be observed across the entire frontal zone of the North Equatorial Countercurrent. In the central region of the frontal zone, one may observe horizontal motions of the upper parts of quasihomogeneous layers with respect to their lower parts and an essential role in the exchange processes is played by turbulence. The peripheral regions of the frontal zone are characterized by the presence of horizontal advection and isopycnic mixing. Far from the frontal interface, the principal contribution to the exchange processes is made by double diffusion. We demonstrate that, for the analysis of the vertical buoyancy fluxes caused by salt fingers, one can use both the Stern relation and the “law of 4/3”. Translated by Peter V. Malyshev and Dmitry V. Malyshev.     

A model of the evolution of vertical thermohaline inhomogeneities of an oceanic thermocline taking into account the effects of double diffusion

We construct a numerical model of the evolution of the structure of an oceanic thermocline in the presence of “salt-finger” convection. The model explains the formation of a piecewise homogeneous vertical structure of the temperature and salinity fields in the ocean. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Analysis of the possibilities of aGALS-3 hydrophysical towed complex

We describe the characteristics of a towed complex used for measurements in the upper layer of the ocean under the conditions of periodic deepening and lifting (scanning) of a carrier with sensors connected with the ship by a weight-carrying cable of constant lengt. For a maximum scanning range of 0–200 m and a towing speed of up to 12 knots, the measurements were performed every 1.5–2.0 km. The minimum vertical scale of recorded temperature and conductivity inhomogeneities is 0.05–0.08 m. We present the results of measurements carried out by the towed complex in a section of the frontal zone in the north-east part of the Tropical Atlantic. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Hardware correction of dynamic errors in measuring salinity by usingCTD-systems

We study the procedures aimed at decreasing the dynamic errors of the evaluation of salinity with the help ofCTD-probes by reducing the difference between the amplitude-phase characteristics of temperature and conductivity sensors. This is attained by introducing a delay between the times of scanning the sensors. To make the amplitude characteristics as close as possible, we propose to use temperature sensors distributed in the direction of probing. We present the procedures used to determine the optimal parameters of temperature sensors and the length of time delay. The advantages of the proposed method are demonstrated by analyzing a numerical example. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

North Brazil current: vertical structure

On the basis of the data ofin situ measurements of the velocities of currents and basic hydrophysical parameters (such as temperature and salinity) carried out during Cruise 41 of the R/VAkademik Vernadsky, we analyze the structure of the North Brazil Current near the continental slope and in the equatorial abyssal part of the ocean in winter, establish the regularities of changes in the current velocity with depth, and compare the structures of the North Brazil and Guiana Currents. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Albedo of clouds and radiation conditions in the oceans

On the basis of the satellite and ship data of many-year observations, we parametrize the albedo of the ocean-atmosphere system both for the conditions of “fair weather” and for the maximum and climatic optical thicknesses of oceanic clouds. These results are used to develop a procedure of practically exact reconstruction of the monthly average fluxes of integral solar radiation and the radiation budget over the ice-free surface of the oceans according to the data of satellite measurements of albedo (Nimbus NOAA satellite, 1974–1983) for arbitrary conditions of transparency of the atmosphere and cloudiness. We determine the current and climatic monthly average values and the characteristics of interannual variability of all components of the radiation mode of the ocean-atmosphere system with a spatial resolution of 500×500 km. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Variability of the horizontal gradients of the air and the water surface temperatures in the vernal frontal zone period of Lake Ladoga

Every year, the during springtime heating conditions, the seasonal thermal frontal zone appears in Lake Ladoga. It features high horizontal water temperature gradients. The coastal waters, stably stratified in density, interact with the waters of the open lake that are unstably stratified because of the free convection developing in the temperature range between 0°C and the maximum density of the water at 4°C. In Lake Ladoga, the advance of the vernal frontal zone lasts about 7?C8 weeks from mid-May to the beginning of July. Both the water temperature and air temperature distributions over the water??s surface show that large spatial temperature ranges exist in the vernal front reaching more than 11°C. We investigated the spatial horizontal gradients of the water??s surface and the air temperature using a spatial grid with a resolution of 5 km. The surface water temperature and the air temperature gradients were compared with each other as well as with the temperatures in the region of varying depths. During the spring peak of the frontal activity in Lake Ladoga, most of the fronts feature mean temperatures greater than 4°C. This indicates that the thermal bar marks the offshore edge of the most extensive frontal zone.     

Long-term variations of the location of the upper boundary of the hydrogen-sulphide zone in the Black Sea

We analyze the dependence of climatic variations of the location of the upper boundary of the hydrogen-sulphide zone in the Black Sea on the variations of the sea level and various types of atmospheric circulation (according to A.A. Girs). It is discovered that the level of correlation between the indicated parameters is high and that the corresponding plots are in good qualitative agreement. The accumulated results enable us to make an assumption that there exists an 80–100-yr cycle of variation of all analyzed parameters and that the long-term variations of the location of the upper boundary of the hydrogen-sulphide zone can be regarded as a manifestation of global climatic variations. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Distinctive features of circulation of waters in the region of the Zmeiny Island under the action of winds of various directions

We use mathematical simulation to study the response of the sea in the region of the Zmeiny Island to the action of winds of various directions. We describe the processes of reconstruction of circulation and thermohaline structure of waters and, in particular, the location and dimensions of the zones of upwelling and downwelling caused by water surges depending on the direction of the wind. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Large-scale inhomogeneities of the tropical Atlantic temperature field

Horizontal gradients of the temperature fields have been calculated by the climatic temperature/ salinity data. Large-scale inhomogeneities and the areas of maximal temperature gradients have been identified and their spatio-temporal variability determined. Translated by Vladimir A. Puchkin.     

Submarine springs of fresh water in the region from Cape Feolent to Cape Sarych

We performed a search for local coastal submarine springs of fresh water in the region from Cape Feolent to Cape Sarych (down to an isobath of 40m). Stable submarine springs of brackish water with the minimum salinity of 5.5‰ and the minimum total output of 30,000 m³/day were discovered only near the west wall of Cape Aiya. It is shown that brackish waters discharging from these springs spread over the sea surface in the form of a thin layer (up to 1 m in thickness) characterized by lower salinity, higher transparency, and an elevated content of silicic acid. We make a conjecture that the appearance of 2–3-m-thick layers of water with higher transparency and lower salinity at depths of 5–8 m is explained by the discharge of unknown bottom springs of underground fresh water. Translated by Peter V. Malyshev and Dmitry V. Malyshev