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In order to simulate the scattering properties of nonspherical aerosol particles in visible and near infrared band precisely and efficiently, a scattering computation model for aerosol particles based on parallel FDTD (Finite Difference Time Domain) is developed. The basic principle of FDTD is introduced, and a new parallel computation scheme for FDTD is proposed, and is realized by MPI repeated non-blocking communication technique. The FDTD scattering model is validated against Lorenz-Mie theory and T Matrix method. Simulation results show that, the scattering properties obtained parallel FDTD scattering model are qualitatively in good agreement with the T matrix method and Lorenz-Mie theory, validating the accuracy of our model. The relative simulation error of Mueller is slightly larger in forward scattering directions than that in backward directions for particles with small size parameter, while for large particles, the result is opposite. [ABSTRACT FROM AUTHOR]

Light scattering by non-spherical particles is an important factor influencing atmospheric radiative transfer. To accurately simulate the scattering properties of non-spherical particles, the Invariant Imbedded T-matrix method (IIM T-Matrix) is developed by combining the Lorenz–Mie theory and invariant imbedding technique. In this model, the non-spherical particle is regarded as an inhomogeneous sphere and discretized into multiple spherical layers in the spherical coordinate system. The T-matrix of the inscribed sphere is firstly calculated by the Lorenz–Mie theory, and then taking it as the initial value, the T-matrix is updated layer by layer by using the invariant imbedding technique. To improve the computational efficiency, the model is further parallelized by the OpenMP technique. To verify the simulation accuracy of the IIM T-Matrix method, the results of the model are compared with those of the EBCM (Extended Boundary Condition Method) T-Matrix method, DDA (Discrete Dipole Approximation) and MRTD (Multi-Resolution Time Domain). The results show that the scattering phase matrix simulated by the IIM T-Matrix method closely agrees with that of the well-tested models, indicating that the IIM T-Matrix method is a powerful tool for the light scattering simulation of non-spherical particles. Since the IIM T-Matrix method is derived from the volume integral equation, compared to the T-Matrix method which is based on surface integral principles (i.e., "EBCM" or the "null field method"), it can be applied to the scattering calculations of particle with arbitrary shapes and inhomogeneous compositions, which can greatly expand the application scope of the T-Matrix method. [ABSTRACT FROM AUTHOR]