Study of underway salinity monitoring device based on optical refractive index measurement

In ocean optics, salinity is an important inherent optical parameter to be measured. In the field of optics, refractive index (RI) is closely related to salinity. Through the real-time detection of the refractive index, we achieved the purpose of underway monitoring the salinity of seawater. We designed a refractive index measurement system based on optical total internal reflection. In this system, the detecting precision of the refractive index of the sea water reached 10-4. Through the conversion of the refractive index, we achieved in-situ measurement of the salinity. In 2016 summer, we accomplished a successful underway measurement in China Yellow Sea. The trends of the results from refractive index are basically agreed with the salinity measurements from electrical conductivity.