垂直观测时水平粗糙地表偏振反射作用研究

POLARIZATION REFLECTION EFFECT OF PLANE ROUGH SURFACE UNDER VERTICAL OBSERVATION

在利用偏振遥感对地表目标或大气进行研究时,由于大气散射光相对地表反射具有更强的偏振特性,故常认为经地气系统反射回空间的太阳辐射偏振信息主要来源于大气,而在遥感反演时常忽略地表的偏振反射作用.这个结论是基于地面目标为漫反射体的假定,但事实上,在绝大多数情况下,地表并非朗伯体,在某些时候这种非朗伯体的地表偏振作用甚至超过大气的影响.本文从推导地表的偏振反射作用机理及偏振光谱解译模型出发,首次利用偏振成像光谱实验,证明了地表的偏振度在某些情况下甚至达到50%以上,说明地表的偏振作用对传感器的信号有时会有很大影响.该作用是进行定量遥感研究时不容忽视的一个重要因素.

When utilizing polarization remote sensing for earth observation, or atmosphere scattering, the polarization effect of atmosphere is always higher than the land surface＇s. It is usually believed that the polarization effect of the atmosphere is the main information resource of the remote sensing sensor. Thus the land surface＇s polarization is often ignored in remote sensing retrieval. This conclusion is based on the assumption that the reflection of land objects is diffuse reflection. However, in most cases, land objects are not standard Lambertian. Sometimes the polarization effect of those objects is stronger than the atmosphere＇s. In this study, the reflection mechanism of the land surface and the interpretation model of polarization spectrum were deduced. Our results show that the imaging spectrum experiment has the land surface polarization effect which can even reach to 50% or more in some cases. The polarization sigrial of sensor will be greatly affected by the land surface. So the polarization effect of land surface is an important factor which can not be ignored during the study of quantitative remote sensing.