Dual-Sensor Approach for Monitoring Coastal Turbidity and Vertical Underwater Visibility Using In-Situ Turbidity Sensors and Satellite Optical Data

Abstract

Accurate and real-time monitoring of underwater visibility is essential for improving the understanding of underwater conditions, particularly in support of maritime search and rescue operations. This study presents a dual-sensor approach integrating in-situ turbidity measurements using turbidity sensors and satellite-based observations via Sentinel-2 multispectral optical sensors. Field measurements were conducted at two stations off the western coast of the Korean Peninsula using the Aqua Troll 500 turbidity probe and Secchi disk to capture vertical turbidity profiles and underwater visibility. Concurrently, surface reflectance data from Sentinel-2 imagery were processed to derive turbidity using a regionally optimized retrieval algorithm. We propose an empirical model relating turbidity to underwater visibility, enabling estimation of spatial visibility distribution across coastal waters. Results demonstrate strong agreement between in-situ and satellite？derived turbidity, confirming the feasibility of remote sensing？assisted underwater visibility prediction. This sensor-integrated methodology offers a scalable solution for operational maritime monitoring and search-support systems.