Soil Moisture Estimates Using -Band Airborne SAR Over Forests Replicating NISAR Observations

IF 4.7 2区地球科学 Q1 ENGINEERING, ELECTRICAL & ELECTRONIC

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Pub Date : 2025-03-13 DOI:10.1109/JSTARS.2025.3544095

Seung-Bum Kim;Xiao-Lan Xu;Simon Kraatz;Andreas Colliander;Michael H. Cosh;Vicky Kelly;Paul Siqueira

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Abstract

Airborne SAR observations of soil moisture conditions at 6-m resolution are analyzed over deciduous and evergreen forests in the U.S. Northeast during the 10-day spring and 14-day summer periods in 2022. During the summer, the dynamic range of HH is about 1 dB, associated mostly with soil moisture changes. Larger changes in backscattering are found between the two seasons, reflecting the vegetation effect. In spring, backscattering decreases in time, suggesting the impact of drying trunks and thickening foliage. In summer, σ° correlates highly with in situ soil moisture, consistently between ascending and descending viewing geometry on flat terrain and on slopes only when imaged at similar incidence angles. The consistency benefits NISAR's retrieval by allowing more frequent consistent retrievals of soil moisture. Soil moisture was retrieved using HH to replicate NISAR observations and its accuracy in the eight sites is 0.067 m³/m³ in unbiased RMSE, assessed over a 140-m domain per in situ site. The results are very encouraging as an independent test of the retrieval algorithm under the challenging conditions of surface slope or forest vegetation. Deficiencies in the retrieval algorithm appear to originate from the modeling of vegetation effect and topography. As long as the two causes are temporally static, they introduce a bias error. However, the temporal range of the retrieval is the most useful property for applications and matches well with in situ observations.

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利用-波段机载合成孔径雷达对森林进行土壤水分估算，复制 NISAR 的观测结果

对2022年美国东北部落叶森林和常绿森林6 m分辨率的土壤水分状况进行了10天春季和14天夏季的航空SAR观测分析。夏季HH的动态范围约为1 dB，主要与土壤湿度变化有关。两个季节的后向散射变化较大，反映了植被效应。在春季，后向散射随时间减少，表明树干干燥和叶片增厚的影响。在夏季，σ°与原位土壤湿度高度相关，在平坦地形和斜坡上，只有在相似入射角成像时，σ°在上升和下降观测几何形状之间保持一致。这种一致性有利于NISAR的检索，因为它允许更频繁、一致地检索土壤湿度。利用HH复制NISAR观测数据反演土壤水分，8个站点的无偏RMSE精度为0.067 m3/m3，评估范围为每个原位站点140 m。作为在地表坡度或森林植被等具有挑战性的条件下对检索算法的独立测试，结果是非常令人鼓舞的。检索算法的不足似乎源于对植被效应和地形的建模。只要这两个原因暂时是静态的，它们就会引入偏差误差。然而，反演的时间范围是应用中最有用的属性，并且与原位观测相匹配。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 地学-成像科学与照相技术

CiteScore

9.30

自引率

10.90%

发文量

563

审稿时长

4.7 months

期刊介绍： The IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing addresses the growing field of applications in Earth observations and remote sensing, and also provides a venue for the rapidly expanding special issues that are being sponsored by the IEEE Geosciences and Remote Sensing Society. The journal draws upon the experience of the highly successful “IEEE Transactions on Geoscience and Remote Sensing” and provide a complementary medium for the wide range of topics in applied earth observations. The ‘Applications’ areas encompasses the societal benefit areas of the Global Earth Observations Systems of Systems (GEOSS) program. Through deliberations over two years, ministers from 50 countries agreed to identify nine areas where Earth observation could positively impact the quality of life and health of their respective countries. Some of these are areas not traditionally addressed in the IEEE context. These include biodiversity, health and climate. Yet it is the skill sets of IEEE members, in areas such as observations, communications, computers, signal processing, standards and ocean engineering, that form the technical underpinnings of GEOSS. Thus, the Journal attracts a broad range of interests that serves both present members in new ways and expands the IEEE visibility into new areas.