Q值的影响因素分析及其参数化

Analysis on Influencing Factors of Q Value and its Parametrization

针对高散射特性的二类水体中难以测量的双向性函数Q,利用HYDROLIGHT模拟观测角为太阳天底角下440 nm处的Q值,并分析环境及水体光学特性对Q值的影响。结果表明,在高散射特性的近岸水体或内陆湖泊水体中,由于散射次数的增加,使得风速、散射相函数等影响因素对Q值影响相对减小,单次散射反照率W_0和太阳大顶角θ成为Q值的主要影响因素;随着深度的增加,双向性函数Q受边界条件和光线入射状况影响的程度逐渐减少,直至不受其影响,而成为只与固有光学量相关的内秉光学量;利用Q值的主要影响因素W_0、θ和上行辐亮度的漫衰减系数K_(L_u)分别对Q值进行参数化,得到Q值的2种参数表达式。

The measurement of bidirectional function Q is difficult in the case of Ⅱ waters, due to their highscattering properties, and the HYDROLIGHT is used to simulate the Q value at the 440 nm wavelength with observation angles at the solar nadir angle. Then the effects of environment and water optical characters on Q value are analyzed. Results indicate that in shore and inland lakes of high-scattering waters, the influence of wind speed, scattering phase function, and other factors on the Q value decreases due to the increase in scattering time. So single albedo（W0） and solar zenith angle （θ） become the main influencing factors. With increasing depth, the effect of conditions such as boundary and incident light on the bidirectional function Q value becomes weaker and weaker until the effect disappears completely. In this case the Q value becomes the internal optical parameter that bears no relationship with the conditions of boundary and incident light. The main influencing factors W0, θ, and diffuse attenuation coefficient KLu of upwelling radiance are used to parameterize the Q value that can be expressed in two ways.