油砂混合水体后向散射系数光谱贡献分离算法Ⅰ：实验理论

摘要

In the water with petroleum pollution,the petroleum will be adsorbed on the surface of suspended particulate matter and form a double-layer structure,which impacts on the spectrum characteristics to the scattering coefficient.It is a key to im-prove the accuracy of the scattering theory model that the contribution of petroleum substances and suspended particulate matter on the scattering spectrum coefficient is be separated.A backward scattering coefficient spectrum measurement system was being built from linkage observation of three kinds of instruments,including DAWN HELEOS Ⅱ18 angle scattering measuring instru-ment (Wyatt company,American),LISST-100-xB size instrument(SEQUOIA SCIENTIFIC,INC,American),HydroScat-6 Sprctral Backscattering Sensor (HS6)(Hobilabs company,American).Many parameters were measured such as voltage value of the scattering intensity,the particle size distribution,particle concentration and backward scattering coefficient in different water samples.Using the Mie scattering theory,a new algorithm to separate the scattering coefficient spectrum and new way of thinking to calculate volume scattering functionβ(λ,θ)of the unknown refractive index material were proposed.The matching experiments were done by selecting quartz sand as particles whose refractive index (m)is known and petroleum sewage collected from different oilfield area.On the basis of matching experiments different water samples with different properties were obtained and related data were determinated.Firstly,according to Mie scattering theory the water volume scattering functionβ(λ,θ)for each sample is calculated.Secondly,the equation was set up which can convert the scattering intensity corresponding to the volt-age valueV(θ)measured by DAWN HELEOS Ⅱ 18 Angle laser scattering instrument into volume scattering functionβ(λ,θ). Thirdly,according to the method of optimum the equivalent refractive index (mos )of the oil sands mixed and the refractive index (mo )of petroleum sewage were estimated;Finally,usingβ(λ,θ)and estimation of mos values and mo values to calculate the backscatter coefficient bb (λ)of all kinds samples,and new algorithms were set up which seperated quartz sand bb,s (λ)and petro-leum sewage bb,o (λ)from mixed water with petroleum and sands respectively.The establishment of these separation algorithms improves the accuracy of the scattering theory model of the water petroleum pollution,on the other hand expands the Mie scat-tering theory in the application of ocean color remote sensing.%在石油类污染水体中,油会吸附在悬浮颗粒物表面而形成一个双层结构,影响水体后向散射系数光谱特征,分离水体石油类物质与悬浮颗粒物对后向散射系数光谱的贡献,能提高水体石油类污染后向散射理论模型的准确性。将美国 Wyatt公司生产 DAWN HELEOS Ⅱ18角度散射测量仪、美国 SEQUOIA 公司生产的 LISST-100x B粒径仪和美国 Hobilabs公司的后向散射仪 HydroScat-6 Sprctral Backscattering Sen-sor(HS6)联动观测,构成后向散射系数光谱测量系统,分别测量不同水样的散射强度电压值、粒径分布及粒径浓度、后向散射系数等参数,提出了利用 Mi e散射理论计算未知折射系数物质的体散射函数β(λ,θ)的新思路及分离后向散射系数光谱的算法。选择已知折射系数m的石英砂作为颗粒物与采自不同油田区域的油污水进行配比,获取不同特性水样,测定相关数据。首先,根据 Mi e散射理论计算出各样本对应的水体体积散射函数β(λ,θ)；其次,建立的DAWN HELEOS Ⅱ18角度激光散射仪测定散射强度对应的电压值V(θ)转化为体积散射函数β(λ,θ)的关系式；再次,根据最优化方法估算出油砂混合的等效折射系数mo s以及油的折射系数mo；最后,利用β(λ,θ)和估算的mo s值及mo 计算出各类样本的后向散射系数bb (λ),分别建立油污水bb,o (λ)和石英砂bb,s (λ)与油砂混合总bb,os (λ)的分离算法。分离算法的建立一方面提高了水体石油类污染后向散射理论模型的准确性,另外一方面拓展了米散射理论在海洋水色遥感中的应用。