基于拉曼-布里渊散射的海水盐度精细探测遥感方法

Method of remotely sensing seawater salinity fine detection based on Raman Brillouin scattering

盐度是海洋学中重要的物理参量之一,其对生物学研究、气候模拟、天气预报以及飓风路径预测都具有极其重要的意义.在基于拉曼光谱的海洋盐度遥感探测中,由于拉曼光谱同时与盐度及海水温度相关,因此反演盐度时,需要参数假设,从而降低探测精度.为实现对盐度的高精度遥感探测,本文提出了融合水体布里渊散射与拉曼散射光谱的盐度精细反演方法.文中根据拉曼光谱的低频部分与高频部分的面积比值与水体温度和盐度有定量的关系,利用最小二乘方法,建立拉曼光谱与温度和盐度的二元函数方程.由于布里渊频移量的大小与介质中的声速相关,而声速变化是由温度和盐度的变化引起,因此布里渊频移量的大小也同时与盐度及海水温度相关.激光雷达遥感探测方法可以同时探测拉曼光谱和布里渊频移这两个参量,因此利用拉曼光谱和布里渊频移与盐度和温度之间的关系,建立了盐度高精度反演模型,并分析了探测结果的误差,得到盐度的反演误差小于0.47‰.

Salinity is an important physical parameter in oceanography.The change of seawater salinity is closely related to the change of marine environment and climate.Investigation of seawater salinity is of great significance for marine biology,climate simulation,weather forecast and hurricane path prediction.At present,in the research of seawater salinity detection based on Raman scattering,the influence of temperature change is ignored,which will cause inaccurate detection results.In order to achieve high-precision detection of seawater salinity,in this paper,a method of combining the precision salinity inversion with ocean Brillouin scattering is proposed.According to the influence of temperature and salinity on Raman scattering spectra,the functional relationship between them is established.Raman scattering spectra and Brillouin frequency shift are used to implement the inversion seawater salinity.The Brillouin frequency shift cannot be obtained directly by the lidar remote sensing method.It can only detect the energy of the echo signal through edge detection,and the photon correlation spectroscopy technology is used to detect the spectra width.The Brillouin frequency shift can be calculated by the energy and spectral width of the echo signal.Therefore,the accurate inversion of seawater salinity can be realized by detecting Raman spectra,Brillouin spectra width and energy signal.The experimental results of Raman spectroscopy are used to verify the established functional relationship,and the inversion error of seawater salinity is less than 0.47‰.In the experiment,the influence of seawater temperature control accuracy of±0.2℃and the detection results of Brillouin spectrum width and energy are analyzed.Through using the error in measurement result of each parameter,the salinity inversion error caused by them is analyzed.Using the Raman spectrum and Brillouin frequency shift,the problem of the accurate inversion of seawater salinity is solved,and the influence of temperature change on salinity inversion is eliminated.This research provides reliable data support for improving the marine environment,early warning of marine disaster and marine meteorological forecast accuracy,and has important research value and significant social benefits.This method also provides a feasible solution for ocean detection lidar used to detect seawater salinity.