Large Area Aboveground Biomass and Carbon Stock Mapping in Woodlands in Mozambique with L-Band Radar: Improving Accuracy by Accounting for Soil Moisture Effects Using the Water Cloud Model

Large Area Aboveground Biomass and Carbon Stock Mapping in Woodlands in Mozambique with L-Band Radar: Improving Accuracy by Accounting for Soil Moisture Effects Using the Water Cloud Model
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DOI：
10.3390/rs14020404
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发表时间：
2022-01
期刊：
Remote. Sens.
影响因子：
--
通讯作者：
Y. Gou;C. Ryan;J. Reiche
Y. Gou;C. Ryan;J. Reiche
中科院分区：
其他
文献类型：
--
作者：
Y. Gou;C. Ryan;J. Reiche

文献摘要

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土壤水分的影响限制了基于雷达的地上生物量碳（AGBC）预测的准确性，以及导致相邻路径之间的区域马赛克条纹由于不同的土壤水分条件在不同的采集日期。在这项研究中，我们利用半经验水云模型（WCM）占后向散射从L波段雷达图像在莫桑比克中部，林地生态系统占主导地位的AGBC检索土壤水分。交叉验证结果表明：（1）标准WCM有效地解释了土壤水分效应，特别是对于AGBC ≤ 20 tC/ha的地区;（2）标准WCM通过减少不同采集日期之间土壤水分条件差异引起的相邻路径之间的条纹，显著提高了区域AGBC镶嵌图的质量。通过应用标准WCM，具有最大土壤水分差异的测试路径的平均预测AGBC的差异减少了18.6%。WCM是AGBC制图的一个宝贵工具，它减少了预测的不确定性和区域镶嵌中的条带效应，特别是在低生物量地区，包括非洲林地和其他林地和稀树草原地区。它可重复用于最近的L波段数据，包括ALOS-2、PALSAR-2和即将到来的SAOCOM和NISAR数据。
Soil moisture effects limit radar-based aboveground biomass carbon (AGBC) prediction accuracy as well as lead to stripes between adjacent paths in regional mosaics due to varying soil moisture conditions on different acquisition dates. In this study, we utilised the semi-empirical water cloud model (WCM) to account for backscattering from soil moisture in AGBC retrieval from L-band radar imagery in central Mozambique, where woodland ecosystems dominate. Cross-validation results suggest that (1) the standard WCM effectively accounts for soil moisture effects, especially for areas with AGBC ≤ 20 tC/ha, and (2) the standard WCM significantly improved the quality of regional AGBC mosaics by reducing the stripes between adjacent paths caused by the difference in soil moisture conditions between different acquisition dates. By applying the standard WCM, the difference in mean predicted AGBC for the tested path with the largest soil moisture difference was reduced by 18.6%. The WCM is a valuable tool for AGBC mapping by reducing prediction uncertainties and striping effects in regional mosaics, especially in low-biomass areas including African woodlands and other woodland and savanna regions. It is repeatable for recent L-band data including ALOS-2 PALSAR-2, and upcoming SAOCOM and NISAR data.