Cramer–Rao Lower Bound for SoOp-R-Based Root-Zone Soil Moisture Remote Sensing
Cramer–Rao Lower Bound for SoOp-R-Based Root-Zone Soil Moisture Remote Sensing
复制标题
基于 SoOp-R 的根区土壤湿度遥感的 Cramer–Rao 下界
DOI：
10.1109/jstars.2020.3029158
复制
发表时间：
2020
影响因子：
5.5
通讯作者：
R. Bindlish
中科院分区：
文献类型：
--
作者：
D. Boyd;A. Gurbuz;M. Kurum;J. Garrison;Benjamin R. Nold;J. Piepmeier;M. Vega;R. Bindlish
机会信号反射计是地球物理遥感的一个成熟领域，越来越多的机载和星载实验证明了这一点。随着这种方法受到越来越多的关注，值得分析Soop-R通过利用通信和导航卫星发射机来检索地下土壤水分（SM）的能力。在这项研究中，Cramer-Rao下限（CRLB）被用来确定可变SoOp-R参数的最佳可实现的估计误差的根区土壤水分（RZSM）的影响。本研究探讨使用多个频率，极化，和入射角测量配置的双层介电剖面。结果还详细说明了可变SM条件对Soop-R系统预测地下SM能力的影响。最普遍的观察是使用至少两个频率来限制地下SM估计的不确定性的重要性。如果使用至少两个频率，则根据表面SM含量以及轮廓的独立测量的数量，轮廓的CRLB可在根区域内检索。对于30 cm的深度，观察到对应于4%RZSM估计精度的CRLB可以用少至两个基于双频的SoOp-R测量来实现。对于该深度，由偏振和入射角提供的增加数量的测量允许感测越来越湿的SM轮廓结构。总体而言，这项研究详细介绍了一种方法，通过该方法，可以设计SoOp-R接收机系统，以实现所需的CRLB使用可用的测量和SM配置文件之间的权衡研究。
Signals of opportunity (SoOp) reflectometry (SoOp-R) is a maturing field for geophysical remote sensing as evidenced by the growing number of airborne and spaceborne experiments. As this approach receives more attention, it is worth analyzing SoOp-R's capabilities to retrieve subsurface soil moisture (SM) by leveraging communication and navigation satellite transmitters. In this research, the Cramer–Rao lower bound (CRLB) is used to identify the effects of variable SoOp-R parameters on the best achievable estimation error for root-zone soil moisture (RZSM). This study investigates the use of multiple frequency, polarization, and incidence angle measurement configurations on a two-layered dielectric profile. The results also detail the effects of variable SM conditions on the capability of SoOp-R systems to predict subsurface SM. The most prevalent observation is the importance of using at least two frequencies to limit uncertainties from subsurface SM estimates. If at least two frequencies are used, the CRLB of a profile is retrievable within the root-zone depending on the surface SM content as well as the number of independent measurements of the profile. For a depth of 30 cm, it is observed that a CRLB corresponding to 4% RZSM estimation accuracy is achievable with as few as two dual-frequency-based SoOp-R measurements. For this depth, increasing number of measurements provided by polarization and incidence angle allow for sensing of increasingly wet SM profile structures. This study, overall, details a methodology by which SoOp-R receiver system can be designed to achieve a desired CRLB using a tradeoff study between the available measurements and SM profile.