## 4 Discussion and Conclusions  
The SIO RAS carbon observation site near Blue Bay in the Black Sea includes devices to observe the marine environment. To obtain a long time series of data in the deep part of the site, two subsurface moorings have been installed. The subsurface moored profiler Aqualog stores the observation data in the internal memory for a retrospective study after the recovery of the mooring. Examples of such analyses can be found in References [6; 24]. In future, these systems should be complemented by sediment traps installed at fixed depths below the profiler's operational depth to assess the composition of the sinking material in the deep layers of the Black Sea. However, the Aqualog profiler cannot measure through the sea surface layer, because its profiling range is limited to the top by subsurface floatation, which supports the mooring wire in an upright position [3]. Sampling through the top layer (0-30 m) in the coastal zone of the Black Sea cannot be achieved using Argo floats, because  
Figure 13: Profiles of the temperature (**upper panel**) and fluorescence-based chlorophyll-a concentrations (**lower panel**) depicted in color for the same period as in Figure 11.  
they do not operate in shallow areas [25]. Sensor chains (strings), which are often used in shallow seas [18], are not sufficient for carbon sites, because they are usually limited to temperature and salinity sensors such as those developed by RBR Ltd. (Ottawa, Canada) ([[https://rbr-global.com/products/standard-loggers/thermistor-strings](https://rbr-global.com/products/standard-loggers/thermistor-strings)]([https://rbr-global.com/products/standard-loggers/thermistor-strings](https://rbr-global.com/products/standard-loggers/thermistor-strings)) (accessed on 21 February 2022)), GeoPrecision GmbH (Ettlingen, Germany) ([[https://www.thermistor-string.com/](https://www.thermistor-string.com/)]([https://www.thermistor-string.com/](https://www.thermistor-string.com/)) (accessed on 21 February 2022)), Aanderaa Data Instruments AS (Bergen, Norway) ([[https://www.aanderaa.com/productsdetail.php?Aanderaa-SeaGuard-String-31](https://www.aanderaa.com/productsdetail.php?Aanderaa-SeaGuard-String-31)]([https://www.aanderaa.com/productsdetail.php?Aanderaa-SeaGuard-String-31](https://www.aanderaa.com/productsdetail.php?Aanderaa-SeaGuard-String-31)) (accessed on 21 February 2022)), Star Oddi Ltd. (Gardabear, Iceland) ([[https://www.star-oddi.com/products/submersible-water-sensors/salinity-logger-probe-CTD](https://www.star-oddi.com/products/submersible-water-sensors/salinity-logger-probe-CTD)]([https://www.star-oddi.com/products/submersible-water-sensors/salinity-logger-probe-CTD](https://www.star-oddi.com/products/submersible-water-sensors/salinity-logger-probe-CTD)) (accessed on 21 February 2022)), and others. Therefore, specific instruments are required to study the carbon system. If multidisciplinary profiles are required, the cost of several sensor suits, along with the mooring line, makes a difference. In addition, the sensor chains need to be deployed at subsurface moorings to avoid the impact of waves; the data are not available for the upper ocean boundary layer. This study describes the new tethered profiler Winchi, which is surface-pierced to obtain full-water column profiles. However, it is capable of sampling through the sea surface layer regularly and frequently during extended deployment. It uses a single sensor suite, thus reducing the cost of the initial investment and maintenance, including post-survey calibration of the sensors. In the future, the profiler will accommodate additional sensors to obtain data on dissolved gases, e.g., carbon dioxide and methane, photosynthetically available radiation (PAR), abundance of chlorophyll, colored dissolved organic matter (CDOM), and pH value, which are required to comprehensively assess the carbon fluxes. We focused on the control of the movement of Winchi to maintain sufficient tension of the wire. It is risky for the profiler mission to ascend in the high seas.