太阳耀光的偏振分析

在水质遥感中,消除水表的太阳耀光是从遥感数据中获取水体信息的关键步骤.通过计算在不同风速和不同太阳天顶角的条件下太阳耀光的偏振度和反射率,分析了利用平行偏振片消除太阳耀光的效果.计算结果表明,当传感器以较小的天顶角对水面进行观测时,偏振片对太阳耀光的过滤作用有限.但是当太阳天顶角较大,传感器在太阳的镜面反射方向附近对水面进行观测时,平行偏振片可以显著地消除水表的太阳耀光.尤其当风速较大时,太阳耀光散布范围大,难以完全回避,此时平行偏振片可以有效地削弱耀光,凸现离水辐射信号,有望提高水体信息提取的精度.

POLARIZATION OF SUN GLINT

To Abstract the information of water body from remotely sensed data, it is important to eliminate the contribution of sun glint reflected by water surface. In this study, the polarization degree and reflectance of sun glint were calculated under different conditions with various wind speeds and sunlight zeniths. These data were used to analyze the effectiveness of parallel polarization plate to eliminate the sun glint. Caculation results show that the effectiveness of parallel polarization plate will be limited when the sensor observes the surface with small zeniths. However, when the sun zenith is large and the sensor observes the water surface near the spectral direction of the sun, a parallel polarization plate can eliminate major part of sun glint. When the wind speed is high, the sun glints will be dispersed in large area and it will be hard to avoid them. Under this condition, using a parallel polarization plate can reduce the contribution of sun glints effectively and increase the contribution of water-leaving radiance relatively. It will be helpful to improve the accuracy of water information Abstraction.