黄东海悬浮颗粒物质量比后向散射特性Mie理论模拟与实证分析  

Mie Theory Simulation and Empirical Analysis of Mass-Specific Backscattering Properties of Suspended Particles in the Yellow and East China Seas

作　　者：曹爽 韩冰[1] 朱建华[1] 李芝凤[1] Cao Shuang;Han Bing;Zhu Jianhua;Li Zhifeng(National Ocean Technology Center,Tianjin 300111,China)

机构地区：[1]国家海洋技术中心,天津300111

出　　处：《激光与光电子学进展》2022年第13期91-101,共11页Laser & Optoelectronics Progress

基　　金：中欧科技合作“龙计划”五期项目(59053);国家重点研发计划(2016YFC1400906,2016YFC1400903)。

摘　　要：悬浮颗粒物的质量比后向散射系数(b*_(bp))主要受颗粒物的成分、大小等因素影响,研究其变化特性对于揭示水体中颗粒物种类、时空分布以及提升水色遥感定量化精度等具有重要意义。本文利用Mie理论,对海水中常见的具有不同粒径分布、相对折射率及表观密度的多种藻类和无机矿物颗粒的质量比后向散射系数进行了模拟计算。研究发现:当粒径分布斜率ξ相同时,无机矿物颗粒的平均b*_(bp)约为藻类颗粒的2倍;ξ为4.0时,无机矿物颗粒和藻类颗粒在532 nm处的平均b*_(bp)分别为(9.12±3.18)×10^(-3)m^(2)·g^(-1)和(4.09±0.48)×10^(-3)m^(2)·g^(-1);藻类颗粒具有较低b*_(bp)的主要原因是其折射率实部较低。黄东海实测数据研究结果表明:b*_(bp)的空间变异性低于后向散射系数,当无机颗粒质量浓度在总颗粒物中占主导时,平均b*_(bp)(532)为8.46×10^(-3)m^(2)·g^(-1);而有机颗粒物占主导时为3.63×10^(-3)m^(2)·g^(-1),前者为后者的2.3倍。实测b*_(bp)随有机颗粒物质量浓度占比的增大呈乘幂函数形式减小,结合模拟结果,发现研究区水体颗粒物的粒径分布斜率ξ的变化范围为3.6~4.2,对于有机颗粒占主导的远岸水体,ξ约为3.9,而在长江入海口附近水域,悬浮颗粒物的质量比后向散射系数因受粒径分布变化的影响具有较大的变化幅度。。The mass-specific backscattering coefficient(b*_(bp))of suspended particles is mainly affected by their composition and sizes.Studying the variation characteristics of b*_(bp) is of great significance to revealing the types and temporal and spatial distribution of such particles in waters and improving the quantitative accuracy of ocean color remote sensing.In this paper,the Mie theory is applied to calculate the b*_(bp) of various common algae and inorganic mineral particles in seawater with different particle size distributions,relative refractive indexes,and apparent densities by simulation.It is found that the average b*_(bp) of inorganic mineral particles is about twice that of algae particles when their particle size distribution slop ξ is the same.When ξ is 4.0,the b*_(bp) of inorganic mineral particles and algae particles at 532 nm are(9.12±3.18)×10^(-3)m^(2)·g^(-1) and(4.09±0.48)×10^(-3)m^(2)·g^(-1) respectively.The lower b*_(bp) value of algae particles can be explained by the lower real part of their refractive index.Research results of the measured data on the Yellow and East China Seas show that the spatial variability of b*_(bp) is lower than that of the backscattering coefficient.When the mass concentration of inorganic particles is dominant in the total particles,the average b*_(bp)(532)is 8.46×10^(-3)m^(2)·g^(-1),which is 2.3 times that,3.63×10^(-3)m^(2)·g^(-1) to be specific,when organic particles dominate.The measured b*_(bp) decreases in the form of power-law function as the mass concentration proportion of organic particles increases.In view of the simulation results,it is concluded that the variation range of the particle size distribution slope ξ of particles in the study waters is 3.6-4.2.In offshore waters dominated by organic particles,ξ is about 3.9.In the vicinity of the Yangtze River Estuary,the b*_(bp) of the suspended particles varies greatly under the influence of the change in the particle size distribution.

关 键 词：海洋光学 质量比后向散射系数 MIE理论 粒径分布 颗粒物组成 黄东海 

分 类 号：P76[天文地球—海洋科学]