CALCULATION OF THE VERTICAL DISTRIBUTION OF THE SPEED OF SOUND IN THE BLACK SEA BASED ON SATELLITE DATA IN THE PERIOD SPRING – AUTUMN 2021
Authors:   State Institution “Hydroacoustic Branch of Institute of Geophysics by S.I. Subbotin name of the National Academy of Sciences of Ukraine”, Ukraine, Sryberko Andrii 
Published: August 2022

The indirect methods for determining the spatial distribution of hydrophysical characteristics in the marine environment become popular today due to the lack of new measured data on these characteristics in the World Ocean. Developed methods allow to simplify creating the model and forecast process for the spatial distribution of hydrophysical characteristics in different water areas of the World Ocean. The results of modeling and forecasting can be used for research and applied purposes. The speed of sound propagation is the main primary acoustic characteristic of the marine environment and the calculation of the vertical distribution of the speed of sound in the Black Sea is a significantly important task. The purpose of the article is to demonstrate the possibility of calculating the vertical distribution of the speed of sound in the active layer of the marine environment based on satellite data and process the detailed analysis of the obtained results. Calculation of the vertical distribution of the speed of sound in the active layer of the Black Sea deep-water area in the spring-autumn period was carried out on the basis of original methods which are based on mathematical and physical-statistical methods of analysis. These methods were developed in the State Institution “Hydroacoustic Branch of Institute of Geophysics by S.I. Subbotin name of the National Academy of Sciences of Ukraine”. Calculations of the vertical distribution of the speed of sound were processed using the “Program module” application. The initial data were daily sea surface temperature data from satellite measurements (NASA: Terra MODIS satellite). The spatial interval of measurements was 4 km in latitude and longitude. One date per month in the period May-October 2021 was selected for the studies. Based on the results of calculations of the vertical distribution of the speed of sound according to satellite data, the maps of its distribution on zonal and meridional oceanographic sections were built. During the analysis of the built maps the features of the vertical distribution of the speed of sound were identified in these sections. An analysis was made of the distribution of the calculated average values and the values of the vertical gradient of the sound speed in the Black Sea in the period spring-autumn 2021. Developed “Program module” application for automatic processing the satellite data has shown good efficiency in research for calculating the vertical distribution of the speed of sound in the Black Sea. Based on the results of the analysis, it was concluded that the developed methods for calculating the vertical distribution of the speed of sound in the marine environment can be used for research and applied purposes in solving applied tasks of hydrography, hydroacoustic, oceanology, marine ecology, navigation, etc. These methods and principles of developing the “Program module” application for calculating the vertical distribution of the speed of sound in the marine environment based on satellite data can be applied to analyze other areas of the World Ocean taking into account their hydrological conditions.