The present study analyses the influence of topography, β-effect, and the gradient of the meridional variability of the background current on the barotropic topographic Rossby waves. We exclude the stratification effect from the problem and consider a vertically integrated zonal flow because the previous results show that short waves are seldom, and the stratification effect on long Rossby waves is insignificant. We consider the transverse (meridional) variability of the background topography current in the WKB approximation. Thus, we obtain a dispersion relation for plane barotropic topographic Rossby waves, which simultaneously accounts for the effects of the Earth’s rotation, velocity shear, and topography. The GLORYS12v1 product for the Antarctic Circumpolar Current zone is used to calculate the current velocity shift. The topography structure is modeled as an elongated ridge and approximated by an exponential and a Gaussian function with different parameters. The results show that the contribution of the shear flow can overlap the contribution of topography locally. The topographic factor in the dispersion relation is dominant. Specifically, in the southern hemisphere, on the northern side of the ridge, the impact of topography on the Rossby waves intensifies due to the β-effect, while, on the southern side, it reduces due the β-effect.

An extensive literature is devoted to the study of the boundary layer of the atmosphere over an inhomogeneous underlying surface. However, the specificity of anisotropic boundary layers, when the effective roughness and drag coefficient depend on the wind direction, has been studied to a much lesser extent. Such situations, in addition to cases of anisotropic relief, exist, for example, when the wind interacts with ordered vegetation (forest plantations) or ordered buildings. There are known facts of anisotropy of resistance over a rough sea surface. In this note, we consider a stationary nonlinear analytical model of the Ekman-type boundary layer with anisotropic resistance. The results show that the effects of anisotropy can be noticeable.

In this research, we apply the method of colocalization of altimetry data and CTD profiles from multiple platforms (research vessels, autonomous profiling floats, and gliders) to study the seasonal variability of thermohaline structures of cyclonic and anticyclonic eddies in the Lofoten Basin. We demonstrate the thermohaline structure of anticyclonic eddies reveals significant seasonal variability manifesting itself in the deepening of positive anomalies in the summer period and decreasing the vertical extension of the eddy cores. We show that a prominent feature of the thermohaline structure of cyclonic eddies is the positive salinity anomalies in the upper layer. We establish mean zonal eddy-induced transport is generally westward in both summer and winter periods. The pronounced seasonal cycle manifests itself in the intensification of zonal and meridional eddy-induced transport in winter.

Characteristic features of a local upwelling observed in October, 2011 in the southwestern part of the Peter the Great Bay, the Sea of Japan, were studied using in situ and satellite observations. The paper presents as well the results of numeric simulation carried out with Regional Ocean Model System (ROMS) with a free surface. Meteorological observations of the wind field inhomogeneities as well as the results of in situ measurements of the seawater structure were used in the calculations. The analysis of in situ data and comparison with the simulation results of the upwelling development revealed that spatial and temporal scale of the phenomenon was determined by the force, the duration and the direction of wind. Inhomogeneity of the wind field over the Peter the Great Bay is closely associated with the peculiarities of coastal orography and leads to an upwelling intensification over some areas of the coast and to the creation of temperature fronts and cross-jets of cold water, transverse to the main current running along the shelf.

The characteristic properties of inertial oscillations in the active layer in the northern part of the Black Sea are discussed based on the analysis of two types of currents measurement data. The results of spectral analysis of the ~100-day series of current velocity pulsations at five horizons (35–350 m) of the autonomous buoy station showed that no less than 70 % of the kinetic energy of the internal waveband is concentrated in the frequency band 2/3f÷3/2f near the local inertial frequency f, as is in other regions of the World Ocean. A characteristic feature of the vertical distribution of the inertial oscillation energy is its fastest decrease in the vicinity of the maximum buoyancy frequency in the main pycnocline. This change in energy with depth confirms the shielding effect of the main pycnocline, which limits the penetration of inertial oscillations into the deep layers of the sea. For the first time, it was established that the ratio of inertial oscillation energy in the total kinetic energy increases with depth (from 8.5 % at the horizon of 50 m to 19 % at the horizon of 350 m). This circumstance highlights the increasing effect of inertial oscillations on the dynamics of deep sea waters. A characteristic damping time of inertial oscillations in the main pycnocline was ~170 h, above pycnocline ~55 h, lower ~70 h. This relative increase in the main pycnocline means an aggravation of the inertial peak in the spectrum, which is typical for other regions of the World Ocean and can be explained by a decrease in the group velocity of near-inertial internal waves due to their interaction with geostrophic flows. Continuous profiles obtained by Lowered Doppler Current Profiler showed a predominance of rotation of the velocity shift vector with depth in a clockwise direction, which determines the downward direction of propagation of inertial internal waves as dominant, and confirms their wind origin. The observed length of the near-inertial internal waves was 20–40 m vertically. The average duration of a wave packet is ~1.5 wavelength.

Sea level variability was analyzed using tide gauge data for 2010–2015 from three Russian hydrometeorological stations located along the open coastline in the Primorye (Liman) Current zone, in the northwestern part of the Sea of Japan. Based on wavelet transform, non-stationary sea level oscillations on the 120–130 and 70–80 days timescales were detected for the first time in the northwestern part of the Sea of Japan. Quasi-biennial, annual, semiannual, tidal diurnal and semi-diurnal, and inertial sea level oscillations found in earlier studies were also registered. The intensity of dynamic processes was estimated from the wavelet spectral power averaged in the 8–40 days range corresponding to lifetimes of mesoscale/submesoscale eddies in the Primorye Current zone. The variability timescales of this intensity were found to match that of the sea level (more precisely, the timescales of 70 days and longer). This implies that the 120–130 and 70–80 days sea level variability can be related to dynamic processes. At the three coastal stations, more than 200 km distant from each other, this kind of variability was in phase before mid 2014 and then diverged.

The results of numerical modeling of the propagation of tsunami waves from several seismic sources of the Azov-Black Sea basin, which represent a potential hazard for the Kerch Strait, are presented. At the first stage, for the entire Azov-Black Sea basin, the evolution of four model sources of tsunami generation was simulated — two sources closest to the strait in the Black and Azov Seas, a remote Black Sea source, and also a source similar to the one that caused the Yalta earthquake on the 12^th September of 1927. The initial conditions were set in the form of an elliptical rise in sea level, the parameters of the ellipse were found according to empirical formulas corresponding to an earthquake with a magnitude of 7. For these foci, tide gauges were analyzed at the entrance to the strait from the Black and Azov Seas. It was revealed that at the entrance to the strait, the Black Sea tsunamis have shorter periods than the Azov Sea ones. At the second stage, the penetration of tsunami waves into the Kerch Strait was modeled on a high-resolution grid. Model data from the first stage were used as boundary conditions at the liquid boundaries of the strait. The identified areas of maximum sea level rise are located along the coast of the strait when waves propagate from both the Black and Azov Seas. It is shown that Tuzla Island has a blocking effect on the propagation of tsunami in the strait.

Reported and analyzed the results of satellite observations of Lake Ladoga water quality parameters (WQPs) primarily in spring 2016 and 2017. Our retrievals indicate that even in March, soon after the inception of ice cover melting, the concentration of chlorophyll a (C_chl) is non-zero (but yet very low) not only in the lateral but also pelagic waters of the lake. Arguably, the non-zero chl concentrations arise from the phytoplankton that vegetated under ice and then moved up to the surface as the ice sheets began melting. Spring-time concentrations of inorganic suspended matter (C_sm) are year-specific and range between 0.1 and 3.5 mg/l with the elevated values inherent in lateral waters, especially in the vicinity of river outflows. Similar spatial patterns are found for the distributions of colored dissolved organic matter concentrations (C_dom). The lowest values of C_dom (<4.5 mgC/l) occurred in the pelagic waters, whereas the highest ones (12–15 mgC/l) resided in the lateral zone, in particular, within/adjacent to the Volkhovskaya Gouba. With the beginning of summer, the above concentrations, C_chl, C_sm, and C_dom, start growing, remaining however less than they are in July.

The sea ice dynamics in the Pechora Sea in winter 2019/2020 was studied basing on satellite and model data of different spatial and temporal resolution. Model fields of air temperature, sea surface temperature and surface wind as well as the surface current fields retrieved from satellite data were used to analyze the main factors influencing the changes in the sea ice area and types. To derive the sea ice characteristics satellite images and measurements of high (Sentinel-1), moderate (MODIS) and low (AMSR2, SMOS) spatial resolution were used. The Arctic portal ensured the instrumental possibility for data visualization to analyze satellite images and geophysical parameter fields of different spatial and temporal resolutions. The verification of the sea ice type structure analysis was done on the bases of the detailed sea ice maps of the Arctic and Antarctic Research Institute, whereas the verification of the sea ice thickness was done using the SMOS estimates. We conclude that intensive North Atlantic cyclones, accompanied by the development of storm winds over the Pechora Sea and by positive air temperature anomalies, are the main reasons for the atypically young sea ice type structure by the end of the winter and for the destruction of the sea ice cover a month earlier than traditionally in mild winters. Presumably, an increase in the number of the North Atlantic cyclones and in their intensity as a result of the Arctic climate changes will lead to sharper changes in the characteristics of the sea ice cover of the Pechora Sea (stronger decrease in the sea ice area and thickness) than for the other regions of the Arctic.

The spatial and temporal variability of the characteristics of surface manifestations of short-period internal waves in the water area of the Kuril-Kamchatka region, obtained from the analysis of satellite images of the Sentinel-1 radar for the summer period of 2019, is studied. 205 satellite images revealed 927 manifestations of internal wave packets containing from 3 to 18 waves per packet. The wavelengths inside the packet ranged from 80 to 1900 meters, with an average value of 400 meters. The front of the leading crest of the waves packet measured from 2 to 70 km, averaging 14 km. The minimum number of waves was registered in the first half of June, and the maximum — in the first half of July. Areas of constant occurrence of internal waves manifestations in summer are identified: in the southern part of the Kuril ridge (near the Islands of Kunashir and Zeleny), near the Pacific coast of the Kamchatka Peninsula (Kamchatka and Kronotsky Bays). The region of frequent occurrence of internal waves in the middle and Northern parts of the Kuril Ridge (over the Vityaz Ridge in the area of Onekotan and Matua Islands) is also highlighted, the intensity of wave manifestations in which is subject to strong intra-seasonal variability. In all the noted generation centers, two predominant directions of wave packet propagation are distinguished: to the East and to the West. Specific examples using optical images from the Landsat-8 Spectroradiometer show that internal waves in the Kuril-Kamchatka region can be generated by both tidal dynamics and vortex structures.

Acoustic Doppler Current Profilers (ADCP) are widely used for deriving velocity vertical profiles. In recent years these devices were also actively explored for estimations of the energy dissipation rate ε by studying longitudinal velocity structure functions (SF). However, these estimates remain questionable because the correspondent SF method is based on the assumption of the fine-scale isotropy and explores the canonical values for Kolmogorov constants. The last ones, as recent direct measurements and numerical computations prove, are highly variable, thus triggering the errors of ε estimations, which may exceed 50 %. This paper presents an approach to derive the retained information, hidden in the raw along-beam velocities data, which can shed a light on the anisotropy parameters. For this, we developed the inter-beam correlations method, based on the analysis of generalized (fourpoint) SF. The explicit expression for transverse SF was derived, which made it possible to check the “4/3 law” directly. The method was tested by processing velocity data, obtained from the convective mixing layer in ice-covered lakes Onega and Vendyurskoe.