Архив статей журнала
Purpose. The work is aimed at developing and implementing a geographic information system (GIS) that provides an opportunity for online work with the Argo floats data in the Black Sea and for its application to assess the float drift velocities in different sea layers.
Methods and Results. The geoinformation system is developed based on a client-server architecture using PostgreSQL DBMS to store the Argo float data, the jQuery, Plotly and mapbox gl libraries and, therefore, to implement a user interface and a cartographic service. The floats drift velocities are calculated and analyzed using the information provided by the Argo project in the public domain. The information is received from the autonomous drifting profiling floats and includes data on their satellite positioning, drift depths and profiling. The velocities at the float drift horizon are calculated using the data on its trajectory, meanwhile GIS assumes the possibility to recalculate velocities swiftly when new observation data are received, adjust calculation methodology, expand the range of statistical characteristics as well as to add a number of additional options. The Argo data array (early 2005 – mid 2022) was included in the system current version to calculate and analyze velocities. Application of GIS made it possible to estimate floats drift velocities in the Black Sea, specify mean velocity values as compared to the previous studies and show its seasonal variability in different layers of the sea.
Conclusions. The online services of the Argo project are complemented by the developed GIS that simplifies processing and scientific analysis of the Black Sea oceanographic data significantly with no need to use additional scripts, data downloads and external visualization systems. The examples of applying the system for the assessment of floats drift velocities at different depths and in certain parts of the sea are shown. In the future, GIS can be supplemented with new modules, such as automatic downloading of Argo data, operating with similar data arrays obtained, for example, from drifters or ADCP current profilers. Besides, it can be applied to any other regions.
Purpose. Development of regional satellite algorithms requires the information on bio-optical properties of a particular water area. The present study is aimed at comparative analysis of bio-optical properties of optically complex waters differing in their trophic status.
Methods and Results. The study combined the results of measuring the spectral bio-optical properties in the waters of the Black, Azov, Barents and Norwegian seas, the Arctic and Southern oceans (Atlantic sector) and Baikal and Teletskoye lakes. Spectral coefficients of light absorption by phytoplankton, non-algal particles and colored dissolved organic matter were measured in accordance with the International Ocean Colour Coordinating Group Protocols. The study areas included the waters with trophic levels from the oligotrophic to the eutrophic ones (the chlorophyll a concentrations in the surface layers varied from 0.066 to 24 mg⋅m−3) and with high heterogeneity in their bio-optical properties: the total non-water light absorption at the wavelength of 438 nm varied from 0.021 to 0.97 m−1.
Conclusions. In all the regions, a high (within an order of magnitude or higher) spatial variability in the values of light absorption coefficients by all the optically active components and their ratios was noted. This fact indicates the optical complexity of waters in each of the regions under study. The regional specificity of parameterization coefficients for light absorption by phytoplankton, non-algal particles and colored dissolved organic matter was shown. The revealed parameterization coefficients for light absorption by the optically active environment components can be used to develop regional satellite algorithms for assessing water quality and productivity indicators. Based on the empirically revealed dependencies, the following additional indicators of water quality were proposed: the euphotic zone depth and the spectral characteristics of downwelling irradiance which can be retrieved based on remote sensing data.
Purpose. The study is purposed at determining modern dynamics of the Lake Sasyk bay-bar (Crimean Peninsula) and the impact of the local seawater intake upon the coastal zone based on long-term in situ observations, satellite data and mathematical modeling. The study was conducted in view of the proposed construction of transverse hydraulic structures.
Methods and Results. Regular (2007–2014) and occasional in situ observations of the coastline dynamics at the Lake Sasyk bay-bar were used. The maximum inter-annual oscillations in the coastline locations are shown to be 5.8 m in the sections to the southeast from the transverse structure (seawater intake) and 3.4–7.2 m – in the sections to the northwest. Seasonal variability is significantly higher: the maximum range is 14.6 m in the sections to the southeast, and in those to the northwest – 26.7 m. The wave climate was investigated. The wave reanalysis data for 1979–2022 have shown that the southwestern direction of waves approaching the coast with a frequency exceeding 30% is most probable. The highest waves also come from this direction. The extreme values of wave characteristics which can occur once in n years were obtained. The mean long-term values of storm numbers in the area under study are given depending on their duration. Application of the GenCade integrated lithodynamic model permitted to obtain the estimates of changes in the coastline position in this area on the interannual scales.
Conclusions. The model calculations made it possible to reproduce the main features and trends in changes of the beach width in the area of the structure obtained due to in situ observations. The mean annual sediment flows in the area under study are directed clockwise (to the southeast) that is conditioned by the coastline orientation and the wave climate features. Difference between the mean annual sediment rates at the area boundaries is negligible – less than 4% of the multi-year average. This fact indicates insignificant impact of the structure upon the sediment total transfer to the southeast.