海洋悬浮颗粒的光谱模拟:ADA与Mie的比较研究

基于海洋悬浮颗粒的折射率、粒径分布特征,利用异常衍射近似ADA(anomalous diffraction approximation)和米(Mie)散射方法进行衰减、吸收和散射效率的光谱模拟,分析两种方法计算结果相对偏差Δc,Δa,Δb及其影响因素,探讨利用计算速度占优的ADA方法进行海洋悬浮颗粒光谱模拟的可行性,研究发现:Δc,Δa,Δb受颗粒粒径、折射率实部和虚部的共同影响,且影响方式复杂;ADA方法满足计算精度(相对偏差小于5%)要求的最小颗粒半径Rmin随折射率和波长等的变化而变化。考虑到ADA与Mie的计算偏差受到多种因素的影响,而且海洋悬浮颗粒组分复杂多样,建议在进行海洋悬浮颗粒光谱模拟时,采用经典的Mie方法,而不是计算相对快速的ADA方法。

Spectral modeling of marine suspended particulate matter: comparison between ADA and Mie computations

The present paper aimed at exploring the feasibility of modeling optical properties of marine suspended particulate matter (SPM) with anomalous diffraction approximation (ADA) method, which had advantage of computation speed over the classic Mie theory. Based on the marine SPM characteristics of refractive index and particle size, attenuation efficiency Q(c) absorption efficiency Q(a) and scattering efficiency Q(b) of SPM were computed by ADA and Mie to analyze their relative error delta(c), delta(a), delta(b) and the variations. The variations of delta(c), delta(a), delta(b) with the particle size, real and imaginary part of refractive index were different and complex. The minimum particle size R(min), with which ADA can be used to give computation results with enough accuracy (relative difference less than 5%), was determined and shown to be influenced by the refractive index and wavelength Classic Mie method, rather than ADA method, was recommended for the spectral modeling of ocean suspended particulate matter.