Research On Fast Algorithm For MIE Scattering Coefficients In Wide Range

The environmental pollution has become serious increasingly, The size of the particles in the air, distribution and other characteristics of analysis and measurement is particularly important, New demands were put forward for real-time nature and the using range of MIE scattering coefficient.An improved algorithm which runs fast for calculating MIE scattering coefficient in the wide range is presented in the paper,which employs the forward recursion,the improved backward recursion and other mathematical methods on the basis of classic MIE scattering theory.At first,this article studied the calculation of the MIE scattering coefficient and achieved the fast calculation of the MIE scattering coefficient in the wide range. The algorithm which employs the improved backward recursion can accurately calculate the extinction coefficient Kext and the scattering coefficient Ksca in MIE,and remarkably reduce the calculation time for it cuts down the calculation cycle times.It can be adapted to calculate the corresponding MIE scattering parameters which have complex refractive index in the wide range for it takes the mechanism which has an appropriate sub-boundary conditions.Secondly, it has analyzed and discussed the MIE scattering coefficient approximate calculation method in the wider application in detail for it is used for low-cost, small on-site equipment needs. Thirdly, it has inversed the particle spectrum width of the atmospheric aerosol using the MIE scattering theory.Some conclusions can be found:(1)The cycle numbers is almost irrelevant to complex refractive index.(2)The continued fractions method usually can get the most accurate result.(3)Time consumed by new algorithms is 10-2-10-3 to continue fractions, and the greatest error is less than 10-5.(4)The algorithm is suit for size parameters from 10-6 to 106 and the real and imaginary parts of complex refractive index from 10-6 to 106. (5)The form of dust aerosol spectrum distribution is in line with Junge spectrum, The spectrum shapes of the aerosol particles are same basically in conditions of different wavelengths, Aerosol particle spectra has three peaks.The results show that: The improved new algorithm is a wide-range, high-precision and fast numerical method, and it is able to meet the requirements of the actual measurement.