Wind-Speed Measurements over Land Using a Doppler Profiler with a 35-GHz Operating Range

Izvestiya, Atmospheric and Oceanic Physics - In this paper we describe a technique for measuring the tropospheric wind profile using a 35-GHz Doppler profiler. The parameters of the equipment and...     

Experience of Studying the Turbulent Structure of the Atmospheric Boundary Layer Using an Unmanned Aerial Vehicle

Izvestiya, Atmospheric and Oceanic Physics - The growing relevance of the use of unmanned aerial vehicles (UAVs) for studying turbulence in the atmospheric boundary layer (ABL) is associated with...     

Comparative Analysis of Arctic Sea Ice Area Derived from Satellite Microwave Radiometry Data (VASIA2 Algorithm) with Ice Charts of the Arctic and Antarctic Research Institute

Izvestiya, Atmospheric and Oceanic Physics - The Arctic Sea ice area, calculated by the VASIA2 algorithm using the SSMIS data during the most intensive melting of the ice cover in 2019, is compared...     

Influence of the Spatial Resolution of Satellite Images on the Values of the Characteristics of Ice-Cover Leads in the Arctic Seas

Izvestiya, Atmospheric and Oceanic Physics - The values of the characteristics of ice-cover leads in the Laptev and East Siberian Seas calculated from satellite images with spatial resolution of...     

A Technique for Photogrammetric Estimation of Albedo of Snow–Ice Surfaces

Izvestiya, Atmospheric and Oceanic Physics - New ways to improve the original technique for assessing the albedo of snow–ice surfaces with the use of ground measurements of incoming solar...     

Impact of Alaskan Stream eddies on chlorophyll distribution in the North Pacific

The impact of the Alaskan Stream (AS) eddies on the chlorophyll a (chl-a) distribution in the central subarctic North Pacific was investigated through analysis of chl-a and altimetry data from satellite observations. Altimetry observations provided the locations of mesoscale eddies in time and space within the maps of chlorophyll distributions. The climatological chl-a distributions averaged in the area and time showing presence of AS eddies suggested that AS eddies contributed significantly to the chl-a distribution in the deep-sea region of the subarctic North Pacific. The chl-a distribution was closely related to the AS eddies regardless of whether the eddy was located in or detached from the AS. A combination of two or three AS eddies sometimes formed high chl-a concentration belts that injected chlorophyll and coastal nutrient-rich waters southward from the Aleutian Islands far into the deep-sea region of the subarctic North Pacific. These results indicate that chl-a distribution in the central subarctic North Pacific was strongly impacted by AS eddies.     

Bathymetry enhancement by altimetry-derived gravity anomalies in the East Sea (Sea of Japan)

The gravity-geologic method (GGM) was used to enhance the bathymetry of the East Sea (Sea of Japan) with satellite altimetry-derived free-air gravity anomalies and shipborne depth measurements. By comparison with the bathymetry model of Smith and Sandwell’s (SAS) approach (1994), GGM was found to have an advantage with short wavelength (≤12 km) components, while SAS better predicts longer wavelength (≥25 km) components, despite its dependency on density contrast. To mitigate this limitation, a tuning density contrast of 10.25 g/cm³ between seawater and the seafloor was primarily estimated by the downward continuation method and then validated by the check points method with GGM. Similarly, SAS is limited by the “A” value in low-pass part of the Wiener filter, which defines the effective range of the wavelength components on bathymetry. As a final result, we present an enhanced GGM bathymetry model by integrating all available data.     

Wave-like aquatic propulsion of mono-hull marine vessels

The present paper describes results of the experimental investigation of a small-scale mono-hull model boat propelled by a localised flexural wave propagating along the plate of finite width forming the boat's keel. Forward propulsion of the boat was achieved through flexural wave propagation in the opposite direction, which is similar to the aquatic propulsion used in nature by stingrays. The model boat under consideration underwent a series of tests both in a Perspex water tank and in an experimental pool. In particular, the forward velocity of the boat has been measured for different frequencies and amplitudes of the flexural wave. The highest velocity achieved was 32 cm/s. The thrust and propulsive efficiency have been measured as well. The obtained value of the propulsive efficiency in the optimum regime was 51%. This indicates that the efficiency of this type of aquatic propulsion is comparable to that of dolphins and sharks (around 75%) and to that of a traditional propeller (around 70%). In contrast with a propeller though, the wave-like aquatic propulsion has the following advantages: it does not generate underwater noise and it is safe for people and marine animals.     

Seabed morphology and gas venting features in the continental slope region of Krishna–Godavari basin,Bay of Bengal: Implications in gas-hydrate exploration

Increased oil and gas exploration activity has led to a detailed investigation of the continental shelf and adjacent slope regions of Mahanadi, Krishna–Godavari (KG) and Cauvery basins, which are promising petroliferous basins along the eastern continental margin of India. In this paper, we analyze the high resolution sparker, subbottom profiler and multibeam data in KG offshore basin to understand the shallow structures and shallow deposits for gas hydrate exploration. We identified and mapped prominent positive topographic features in the bathymetry data. These mounds show fluid/gas migration features such as acoustic voids, acoustic chimneys, and acoustic turbid layers. It is interesting to note that drilling/coring onboard JOIDES in the vicinity of the mounds show the presence of thick accumulation of subsurface gas hydrate. Further, geological and geochemical study of long sediment cores collected onboard Marion Dufresne in the vicinity of the mounds and sedimentary ridges shows the imprints of paleo-expulsion of methane and sulfidic fluid from the seafloor.     

Naming undersea features of the Sea of Japan: History and modern problems

This communication is dedicated to the investigation history and naming of the undersea morphostructures of the Sea of Japan for the last 50 years. Many of them were first described and studied during long-term geological-geophysical investigations in this basin carried out by Russian scientists. The analysis of 60 names of its undersea feature names revealed that only approximately half of them are cited in the GEBCO Gazetteer some of the undersea morphostructures are known under two or more names, the origin of their names is unknown, or their names were chosen voluntarily. For maintaining the priority of Russian investigations, the nomenclature and names of the undersea features should be adjusted in accordance with the national and international principles and regulations.