Simultaneous measurement of water temperature and salinity using Raman spectroscopy

Abstract

We present a method to simultaneously determine water temperature and salinity, which uses a pulsed excitation laser and a three-channel Raman spectrometer. The method relies on the systematic dependence of the Raman OH stretching band on temperature and salinity, and is compatible with LiDAR techniques. We have measured the variation of the OH stretching band in two seawater samples and a NaCl solution, and constructed a linear mapping between signal ratios derived from the three spectral channels and the temperature and salinity of each sample. For the natural seawater this approach has been determined by cross-validation to have a predictive accuracy of ±1.6 PSU and ±0.5 °C.