太湖悬浮质对湖面反照率及水体光吸收的影响

EFFECTS OF SUSPENDED PARTICLES IN TAIHU LAKE ON ALBEDO AND ABSORPTION

本文根据Mie散射理论,利用太湖水中悬浮质粒径谱分布的实测资料,计算了湖水的光散射相矩阵,消光系数和吸收系数等光学参量,并采用Monte Carlo方法,研究了湖面反照率和水体光吸收以及太阳高度角、入射光波长、底泥反射、悬浮质浓度和粒径分布变化的影响。数值计算结果表明:在研究湖泊水体对太阳辐射能量的反射和吸收时,水中悬浮质是一个不可忽视的重要因素。

The observed size distribution of suspended particles in Taihu lake are used, their light scattering phase matrices and extinction and scattering coefficients are computed by using Mie theory in this paper. Moreover, in terms of Monte Carlo method, the lake surface albedo and absorption of water body are investigated and the effects of solar zenith angle, the inciden light wavelength, the reflection of lake bottom and the concentration and size distribution of the particles are also studied. The results show that the suspended particles in the lake can not be ignored in the study of reflection and absorption of water body, particularly when solar zenith angle is low and concentration of suspension is high. Their multiscattering contribution may be up to six-fold larger than Fresnel reflection of surface and, on the contrary, the effect of water molecules appears mainly in the absorption. In addition the albedo and absorption also vary with incident light wavelength and size distribution of particles. The influences of bottom mud are evident only when water is clear.