Evaluation of Low-Cost Hydrographic Sensors for Increased Monitoring Density in Coastal Oceans

Appropriate ocean monitoring is usually conducted with research vessels using specialized equipment and trained personnel and is therefore necessarily very cost intensive. Al-though this approach makes it possible to map large-scale developments, it is not suitable to detect small-scale and rapid processes reliably, especially in highly variable coastal zones. Ships of opportunity like fishing vessels that work in low fre-quented zones can be used to acquire data with higher resolution. In this case compact low-cost sensors can be used to achieve a scalable approach. For this purpose, a sensing system is designed, which can acquire data autonomously for different monitoring aims. To evaluate the quality of suitable low-cost sensors for this system we present a sensor carrier that can interoperate with a variety of OEM sensors. We selected sensors to measure conductivity, pressure, and temperature with costs below 400 € in total and deployed them alongside instruments of a research vessel, that is used for official monitoring programs in the Baltic Sea. The results show that the chosen sensors reach a high degree of congruence compared to established monitoring solutions, under consideration of the sensors specifications. Extending the overall system makes it possible to use ships of opportunity to complement the monitoring of oceans with autonomous measurements.