Comparison of Three Brillouin Ocean Lidar Models for Estimating Temperature and Salinity

Brillouin scattering lidar is a potential remote sensing technique for measuring the distribution profiles of temperature and salinity in the upper ocean. To realize high-precision simultaneous inversion of temperature and salinity in seawater, we propose a solution tailored for the measurement of temperature-salinity profiles. Three distinct models with error correction are discussed based on dual-wavelength, dual-angle, and dual-parameter approaches, respectively. We analyze the accuracy of these three inversion models using the least squares method based on the actual temperature and salinity data of World Ocean Atlas 2023 (WOA23). The results show that the average temperature and salinity errors for the dual-wavelength model are 0.009 degrees C and 0.001 parts per thousand, for the dual-angle model are 0.13 degrees C and 0.30 parts per thousand, and for the dual-parameter model are 0.03 degrees C and 0.08 parts per thousand. And on this basis, we inverse the temperature and salinity of 0-200 m upper seawater in the South China Sea by employing the dual-wavelength model with the average inversion errors of 0.05 degrees C and 0.02 parts per thousand, respectively. The findings presented in this work hold significant importance for the application of Brillouin lidar in remote sensing the distribution of temperature and salinity in ocean.