海洋遥感偏振特性分布与偏振误差补偿方法

The Polarization Characteristics Distribution and Correction Method of the Polarization Coupling Error in Ocean Remote Sensing System

为了提高海洋水色卫星遥感的定量参数反演精度,确定入瞳处的偏振信号对传感器响应的影响逐渐受到重视。以Aqua-MODIS为例,分析了海洋卫星传感器大视场范围内的偏振特性分布,发现无论是大气程辐射还是考虑海表贡献的入瞳光,视场内偏振特性的变化与观测几何的变化密切相关。相比海表的偏振贡献而言,大气是偏振光的主要来源。在此基础上,研究了遥感器在不同偏振灵敏度条件下对入瞳处的偏振信号的响应以及由此引起的系统误差,发现只有当偏振灵敏度不超过2%时可以满足反演离水辐射产品的需要。提出了补偿大气偏振测量误差的方案,能够较好地提高卫星数据的利用率和遥感器的辐射测量精度。

With the development of the quantitative researches using ocean color remote sensing data sets,study on reducing the uncertainty of the response of the ocean color remote sensors to the polarization characteristics of the target has been attracting more and more attention recently.Taking MODIS as an example,the polarization distribution in the whole field of view was analyzed.For the atmosphere path radiance and the apparent radiance considering the coupling between ocean surface and atmosphere,the polarization distribution has a strong relation with the imaging geometry.Compared to the contribution of the polarization from the rough sea surface,the contribution from the atmosphere is dominated.Based on the polarization characteristics in the field of view,the influence of the polarization coupling error on the quality of the satellite data was studied with the assumption of different polarization sensitivities.It was found that errors due to polarization sensitivity in the field of view are lower than water leaving radiance only when the polarization sensitivity is less than 2%.And in this case it can meet the need of the retrieval of water leaving radiative products.The method of the compensation for the polarization coupling error due to the atmosphere is proposed,which proved to be effective to improve the utilization of satellite data and the accuracy of measured radiance by remote sensor.