## 3 Trials  
The trials of the profiler Winchi were carried out at Lake Glubokoe (Moscow region) and at the SIO RAS carbon observational site on the Northeastern Black Sea shelf. For sea trials, the profiler mooring system was deployed at 25-30 m (location depicted as circle mark No. 4, as shown in Figure 1). The overall design of the mooring is shown in Figure 11. Anchor, acoustic release, and recovery flotation were used in the lower part of the profiler mooring system to recover the mooring. A profiler winch wire was attached to the top of the recovery float. If the data very close to the bottom layer were wanted to be obtained, the U-style mooring could be used.. In a U-style mooring system, a taut line runs from the tethered profiler anchor to the second anchor (located at a distance approximately equal to the depth of the deployment site) which is joined by another line to a surface buoy. Figure 10: Typical profiling track (profiler depth versus time) and energy consumption under the conditions of a weak sea current less than 0.3 m/s. Blue circles indicate the depth of the profiler during deployment. Energy consumption is denoted by red dots. The black circles indicate regimes of the winch motor operation, i.e., the motor power rates are 60% when the profiler ascends and descends, 25% when the ascend speed slows down in the sea surface layer, and 0% when the profiler is on the sea surface. The microelectronic control unit of the system is switched to sleep mode when it is parked on the near-bottom layer. The profiler was configured in advance for automatic operation. The measurement depths, intervals, and other settings could be modified based on GSM communication every time the profiler surfaced. A sample plot of the profiler track is shown in Figure 12. To check the operability of the profiler, the device was scheduled to generate a few fast cycles at the beginning of the mission; therefore, descent and ascent were carried out without long stops at the parking depth. Subsequently, the device automatically switched to a profiling interval of 2 h. After 4 days, the profiler received a command from the operator to change the profiling interval to 1 h. The next day, this setting was changed (Figure 12). Figure 11: **Upper part—Schematic of the profiler mooring system. Top left—The profiler at the parking position: (1)—the profiler Winchi, (2)—flotation, (3)—acoustic release, and (4)—anchor. Top right—The profiler after ascent to the sea surface. Lower part—Sea trials near Blue Bay in the Northeastern Black Sea. Bottom left—Deployment of the profiler Winchi mooring system. Bottom right—The profiler on the sea surface. **  
As an example of data that can be obtained using Winchi, Figure 13 shows the distributions of the temperature and chlorophyll-a for the same period as illustrated in Figure 12. The profiling allowed us to observe temporal variations in the vertical stratification. The temperature measurements (upper panel of Figure 13) exhibited a water mass up to 19.5-20.5 \({}^{\circ}\)C on the upper layer (15-20 m) of the shelf water. The narrow thermocline separated the warm water mass from the near-bottom layer, which was colder than that at 13 \({}^{\circ}\)C. In October, strong stratification can be supported by the along-shelf advection of light, warm water from the southeastern part of the sea and upwelling events, which led to the propagation of dense, cold water from the deep part of the sea above the continental slope and over the shelf [18]. The warmer upper layer was rather poor in chlorophyll-a (Figure 13, lower panel). The chlorophyll-a concentration increased to 2-2.5 \(\upmu\)g/L near the sea bottom, where the water was thought to be nutrient-rich. The observed maximum of chlorophyll-a below 15 m in depth is a characteristic feature of the Black Sea ecosystem [19, 20, 21]. The clear-cut diurnal cycle of the chlorophyll-a measurement data obtained by the SCF sensor in the upper 10-m layer (lower panel of Figure 13) should be treated with caution.