To obtain new information about surface waves, it is proposed to use an underwater acoustic wave gauge, and an assessment of its effectiveness can be performed using a numerical simulation and field experiment. A new device, an underwater acoustic wave gauge named “Kalmar”, was developed by the Institute of Applied Physics of the Russian Academy of Sciences for long-term, all-weather monitoring of wind waves. The instrument uses ultrasound to probe the water surface from underwater and can be used to verify remote sensing data. In this work, the capabilities of the device are tested and compared with ADCP data. Two independent methods for processing underwater acoustic wave gauge data are discussed and compared. One of them is completely new for acoustic measurements and is based on the analysis of the shape of the reflected acoustic pulse averaged over space and time. The other allows processing individual reflected pulses and calculating the time implementation of the distance to the water surface. It is shown that two independent methods of significant wave height retrieval from the acoustic wave gauge measurements are highly correlated. The “Kalmar” acoustic wave gauge and the RDI WH-600 acoustic Doppler current profiler operated simultaneously at the test site in Gelendzhik from 1 February to 10 February 2020. The significant wave heights measured by the two instruments are in good agreement.

On June 7, 2018, a sub-mesoscale anticyclonic eddy induced by the wind (north-east) was registered on the shelf in the area of the city of Gelendzhik. With the help of field multidisciplinary expedition ship surveys, it was shown that this eddy exists in the layer above the seasonal thermocline. At the periphery of the eddy weak variability of hydrochemical parameters and quantitative indicators of phytoplankton were recorded. The result of the formation of such eddy structure was a shift in the structure of phytoplankton – the annual observed coccolithophores bloom was not registered.

This model provides a periodic measurement of temperature profiles from the bottom layer to the water surface in a programmable mode using temperature and pressure sensors placed in a single streamlined body (probe). The probe is connected by a thin resistant cable to the bottom block of the station, including a winch and an electronic unit. This cable provides power to the probe sensors, and transmits data to the station’s solid-state memory. Initially, the cable is wound on the winch drum, and the probe is located near the bottom block of the station. The probe has positive buoyancy. When turning on the winch to unwind the cable, the probe starts to go up. After it reaches the water surface and stays there for a short time, the winch turns back, the cable is wound onto the drum, and the probe is pulled down until it reach the bottom block. Measurements of parameters are carried out when the probe moves up and down with fine-scale vertical resolution. During regular use of the station in the water area of the IO RAS Gelendzhik Research Site on the Black Sea, the measurement data will not only be recorded in the station’s memory, but also promptly transmitted to the coastal center via a cable laid across the sea floor. This cable will also provide power to the station. Preliminary laboratory and field tests of the main components of the station are conducted. In the developed version, the station is designed for long-term monitoring of the hydrological structure of the marine coastal zone in operative mode. It may be retrofitted with bio-optic and hydrochemical sensors for environmental monitoring of reservoirs, the depth of which does not exceed 50-100 m.

This paper discusses the new data obtained from field observations in the summer of 2012 at Lake Shira, which supplement research over three summer seasons of 2009-2011. The instruments used for measurements are described, as well as the results of field measurements.