Validation of downscaled 1-km SMOS and SMAP soil moisture data in 2010–2021

IF 2.5 3区地球科学 Q3 ENVIRONMENTAL SCIENCES

Vadose Zone Journal Pub Date : 2024-01-17 DOI:10.1002/vzj2.20305

Bin Fang, Venkataraman Lakshmi, Runze Zhang

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引用次数: 0

Abstract

Soil moisture (SM) is an important component for many applications in agriculture, hydrology, meteorology, and ecology. In past decades, passive/active microwave sensors onboard Earth observation satellites are utilized to obtain SM estimates from radiometer or radar observations. In this study, the Soil Moisture and Ocean Salinity (SMOS) Level 3 daily SM retrievals at 25-km spatial resolution between 2010 and 2021 were downscaled through an apparent thermal inertia principle-based algorithm. The 1-km downscaled SMOS SM retrievals were validated by in situ measurements from 635 sites of 19 SM networks in the world, which were acquired from the International Soil Moisture Network and Texas Soil Observation Network. Additionally, the validation results of the SMOS SM products were compared with those of the Soil Moisture Active Passive (SMAP) global Level 2 enhanced SM products at 1-km downscaled and original 9-km resolution in 2015–2021. It shows that the downscaled SMOS SM data have an overall improved accuracy and outperform the coarse-resolution 25-km data, with a lower unbiased Root Mean Squared Error of 0.114 m³/m³ on average.

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验证 2010-2021 年缩小尺度的 1 公里 SMOS 和 SMAP 土壤水分数据

土壤湿度（SM）是农业、水文学、气象学和生态学等许多应用领域的重要组成部分。在过去几十年中，地球观测卫星上的被动/主动微波传感器被用来从辐射计或雷达观测中获取土壤水分估算值。在这项研究中，通过基于视热惰性原理的算法，对 2010 年至 2021 年期间 25 千米空间分辨率的土壤水分和海洋盐度（SMOS）第 3 级每日土壤水分和海洋盐度检索进行了降尺度处理。通过国际土壤水分网络和德克萨斯土壤观测网络获取的全球 19 个土壤水分网络 635 个站点的原位测量数据，验证了经缩小比例的 SMOS 1 公里土壤水分检索结果。此外，还将 SMOS SM 产品的验证结果与 2015-2021 年 1 千米降尺度和原始 9 千米分辨率的全球土壤水分主动被动（SMAP）2 级增强 SM 产品的验证结果进行了比较。结果表明，降尺度的SMOS SM数据总体上提高了精度，优于粗分辨率的25千米数据，无偏均方根误差平均为0.114立方米/立方米。

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来源期刊

Vadose Zone Journal 环境科学-环境科学

CiteScore

5.60

自引率

7.10%

发文量

审稿时长

3.8 months

期刊介绍： Vadose Zone Journal is a unique publication outlet for interdisciplinary research and assessment of the vadose zone, the portion of the Critical Zone that comprises the Earth’s critical living surface down to groundwater. It is a peer-reviewed, international journal publishing reviews, original research, and special sections across a wide range of disciplines. Vadose Zone Journal reports fundamental and applied research from disciplinary and multidisciplinary investigations, including assessment and policy analyses, of the mostly unsaturated zone between the soil surface and the groundwater table. The goal is to disseminate information to facilitate science-based decision-making and sustainable management of the vadose zone. Examples of topic areas suitable for VZJ are variably saturated fluid flow, heat and solute transport in granular and fractured media, flow processes in the capillary fringe at or near the water table, water table management, regional and global climate change impacts on the vadose zone, carbon sequestration, design and performance of waste disposal facilities, long-term stewardship of contaminated sites in the vadose zone, biogeochemical transformation processes, microbial processes in shallow and deep formations, bioremediation, and the fate and transport of radionuclides, inorganic and organic chemicals, colloids, viruses, and microorganisms. Articles in VZJ also address yet-to-be-resolved issues, such as how to quantify heterogeneity of subsurface processes and properties, and how to couple physical, chemical, and biological processes across a range of spatial scales from the molecular to the global.