基于笔形波束扫描微波散射计的高分辨率处理技术研究

Currently, the operational scatterometers generally produce mesoscale backscattering measurements with a true spatial resolution of more than 25 km. Therefore, scatterometer data is unavailable for some high-resolution applications, such as surface snow/freeze-thaw, polar sea ice and coastal areas. A new design of scatterometer, namely dual-frequency polarized scatterometer (DPS), is now under developing in China. DPS combines the range-Doppler technique and deconvolution reconstruction technique for high density sampling to achieve high-resolution backscatter measurements within a wide swath (larger than 1000 km). This project investigates the high-resolution processing technology of high density sampling scatterometer data, and explores the backscattering coefficient reconstruction model and the high-resolution processing algorithms. Then it analyzes the measurement performance of DPS and its optimal parameter setting. The main objective of this project is to develop a sophisticated model to analyze the relationship between the spatial resolution and reconstruction precision/accuracy of high-resolution processing algorithms, and leads to a complete set of high resolution processing for scatterometer data. Finally, such process is used to produce the backscattering coefficients products of high quality and high-resolution (less than 5 km). The results of this project will improve our understanding of the relationship between resolution and reconstruction precision/accuracy in high-resolution processing, promote the scientific researches and applications of scatterometer data over land, sea ice and coastal areas, and provide the necessary theoretical and technological supports for the upcoming Chinese DPS.

当前业务化微波散射计的真实分辨率通常大于25km，无法满足地表积雪/冻融、极地海冰和近海岸区域等高分辨率应用的需求。我国新型的双频极化微波散射计（DPS）将结合距离—多普勒分辨技术和高密度采样反卷积重建技术，实现宽刈幅（优于1000km）的高分辨率后向散射测量。本项目基于DPS深入研究高密度采样的散射计数据高分辨率处理技术，探讨散射计后向散射系数重建模型及相应的高分辨率处理算法，并分析DPS测量性能，优化系统参数设置。重点开发高分辨率处理的空间分辨率和重建误差定量评估体系，形成一套完整的散射计数据高分辨处理流程，产生相应的高质量的高分辨率（≤5km）后向散射系数产品。项目的研究成果有助于改善人们对高分辨率处理的分辨率和误差关系的认识，促进散射计数据在陆地、海冰以及近海岸区域的科学研究和应用，并为DPS系统开发提供必要的理论支撑和技术储备。

微波散射计具有观测刈幅宽、全球覆盖周期短、测量精度高等优点，正逐渐成为陆地定量遥感的最佳选择。然而，对于空间分辨率要求较高的陆地参数观测而言，现有的散射计数据仍存在一定的局限性。我国新型的双频极化微波散射计（DPS）将结合距离—多普勒分辨技术和高密度采样反卷积重建技术，实现宽刈幅（优于1000km）的高分辨率后向散射测量。本项目对DPS散射计高分辨率处理进行了系统深入地研究。首先，构建了一套较为完整的散射计数据高分辨率处理方法，具体包括基于高密度采样的散射计高分辨率处理模型搭建、高分辨率处理算法研究、高分辨率处理算法空间分辨率和重建误差定量评价方法开发，高分辨率处理算法性能分析和验证以及调谐参数查找表制作。其次，项目围绕DPS散射计高分辨率处理全过程，开展了地表雪水当量SWE正演、DPS散射测量、高分辨率处理及调谐参数选取的研究，并分析了DPS散射计雪水当量后向散射系数高分辨率重建性能，发现L2算法所能获得的最优分辨率约为3 km（Kp=0.2-0.3 dB）、4 km（Kp=0.4 dB）和5 km（Kp=0.5 dB），L1和TV算法所能获得的最优分辨率约为3 km（Kp=0.2-0.3 dB） 和4 km（Kp=0.4-0.5 dB）。项目所取得的研究成果促进了散射计数据高分辨处理领域的发展，推动了国内散射计后向散射数据高分辨率后向散射系数产品的研发，并为新型高分辨率散射计系统的设计提供了必要的理论和技术支撑。