散射相函数是研究气溶胶中光传输特性的一个重要参量。对比了大气辐射传输中的蒙特卡罗仿真常用的4种近似散射相函数, 针对二项Henyey-Greenstein(TTHG)相函数的参数不易确定的问题, 提出了一种基于粒子群优化的TTHG散射相函数, 该函数可以很好地拟合Mie散射相函数, 尤其是在大于90°的后向散射方向效果更加明显。相比于HG、HG*、RHG等相函数, 文中提出的相函数可以更好地逼近实际散射情况, 得到更精确的蒙特卡罗仿真结果。

The scattering phase function is an important parameter for studying the optical transmission characteristics in aerosols. Four approximate scattering phase functions commonly used in Monte Carlo simulations in atmospheric radiation propagation were compared. Aiming at the problem that the parameters of the Two-Term Henyey-Greenstein (TTHG) phase function were difficult to determine, a TTHG scattering phase function based on particle swarm optimization was proposed. This function can well fit the Mie scattering phase function, especially at backscatter angles greater than 90°. Compared with the phase functions such as HG, HG* and RHG, the phase function proposed in this paper can better approximate the actual scattering and obtain more accurate Monte Carlo simulation results.