On October 3, 2024, the 133^rd cruise of the R/V Professor Vodyanitsky was completed. During the 23-day expedition, from September 11 to October 3, a total of 24 researchers from three scientific institutes (Marine Hydrophysical Institute, A.O. Kovalevsky Institute of Biology of the Southern Seas and Institute of Natural and Technical Systems) participated in oceanographic, hydrobiological and hydrochemical studies of the Black Sea water area.

The expedition included 13 scientists from Marine Hydrophysical Institute, representing the hydrology, hydrochemistry, hydrometeorology, optics and turbulence units.

Throughout the 133^rd cruise expedition, scientists of MHI carried out climatic monitoring of the active layer of the Black Sea, studied the transformation of the waters of the CIL in the autumn period, measured the vertical distribution of current velocity in the studied areas, conducted radiochemical studies, performed optical studies, investigated the fine structure and microstructure of hydrophysical fields.

In order to achieve the set goals, the following tasks were accomplished during the expedition:

Hydrology Unit

• experimental data on the vertical distribution of seawater temperature and salinity, new experimental data on the spatial and temporal structure of current velocity were obtained;
• search and lifting of the submerged buoy station installed during the 129^th cruise of the R/V Professor Vodyanitsky was performed;
• a submerged buoy station with sedimentation traps and current meters (FNNN-2023-0001) was installed.

Hydrochemistry Unit

• seawater samples were collected and thorium-234 and beryllium-7 were concentrated in dissolved and adsorbed on suspension forms.

Hydrometeorology Unit

• measurements of hydrometeorological parameters were made at stations and crossings.

Turbulence Unit

• measurements of the fine structure and microstructure of hydrophysical fields in the upper layer of the sea were carried out using a microstructure probe;
• the characteristics of the vertical turbulent exchange in the northern part of the Black Sea near the Crimean coast on the shelf, in the area of the depth drop and in the open part were calculated on the basis of in-situ data using the developed methodology;
• data were collected to analyze spatial variations of turbulent exchange intensity;
• dependencies of turbulent diffusion coefficients on stratification parameters were obtained.

Optics Unit

• regular measurements (every half hour) of direct solar attenuation by SPM photometry in clear weather and measurements of the spectral brightness factor of the sea during daytime flybys of satellites with sea color scanners have been performed.

The following scope of work was carried out at 100 stations:

• 53 soundings with the hydrological-hydrochemical sounding complex IDRONAUTOCEANSEVEN 320 PlusM;
• 49 soundings with CTD 48 M;
• 75 soundings with the acoustic Doppler current meter WorkhorseMonitor 300 kHz ADCP.
• hydrometeorological parameters (wind speed and direction, air and sea temperature, relative humidity, air pressure, wave height (visually)) were measured at 100 stations with the CRCG complex;
• 1 submerged buoy station with 24 differential sediment samples and 19 integrated sediment samples was deployed;
• 1 submerged buoy station with differential and integral sediment samplers and acoustic current meters was deployed;
• 46 seawater samples were collected at 35 stations and radionuclides (beryllium-7 and thorium-234) were concentrated in dissolved and adsorbed on suspension forms;
• 36 changes in the brightness spectra of the sea upwelling were made with a deck spectrophotometer at 36 stations;
• 36 measurements of relative transparency were made with the Secchi disk at 36 stations;
• 240 measurements of atmospheric spectral transparency were made with the SPM solar photometer;
• new buoyancies were tested at 5 stations and the configuration of buoyancies and weights was selected for the correct descent rate of the free-fall profiler;
• 24 vertical soundings were made at 23 stations with the MSS90L profilograph at depths ranging from 50 to 550 m. Profiles of temperature, temperature pulsation, conductivity, current velocity pulsation, turbidity, chlorophyll-a and oxygen were obtained.