Evaluation of ESA Active, Passive and Combined Soil Moisture Products Using Upscaled Ground Measurements
Zhu, Luyao1; Wang, Hongquan1; Tong, Cheng1; Liu, Wenbin2; Du, Benxu3
Source PublicationSENSORS
Corresponding AuthorWang, Hongquan(Hongquan_Wang@zju.edu.cn)
AbstractThe European Space Agency (ESA) Climate Change Initiative (CCI) project combines multi-sensors at different microwave frequencies to derive three harmonized soil moisture products using active, passive and combined approaches. These long-term soil moisture products assist in understanding the global water and carbon cycles. However, extensive validations are a prerequisite before applying the retrieved soil moisture into climatic or hydrological models. To fulfill this objective, we assess the performances of three CCI soil moisture products (active, passive and combined) with respect to in-situ soil moisture networks located in China, Spain and Canada. In order to compensate the scale differences between ground stations and the CCI product's coarse resolution, we adopted two upscaling approaches of Inverse Distance Weighting (IDW) interpolation and simple Arithmetic Mean (AM). The temporal agreements between the satellite retrieved and ground-measured soil moisture were quantified using the unbiased root mean square error (ubRMSE), RMSE, correlation coefficients (R) and bias. Furthermore, the temporal variability of the CCI soil moisture is interpreted and verified with respect to the Tropical Rainfall Measuring Mission (TRMM) precipitation observations. The results show that the temporal variations of CCI soil moisture agreed with the in-situ ground measurements and the precipitation observations over the China and Spain test sites. In contrast, a significant overestimation was observed over the Canada test sites, which may be due to the strong heterogeneity in soil and vegetation characteristics in accordance with the reported poor performance of soil moisture retrieval there. However, despite a retrieval bias, the relatively temporal variation of the CCI soil moisture also followed the ground measurements. For all the three test sites, the soil moisture retrieved from the combined approach outperformed the active-only and passive-only methods, with ubRMSE of 0.034, 0.050, and 0.050-0.054 m(3)/m(3) over the test sites in China, Spain and Canada, respectively. Thus, the CCI combined soil moisture product is suggested to drive the climatic and hydrological studies.
KeywordESA CCI soil moisture validation ground measurements upscaling spatiotemporal analysis
Indexed BySCI
Funding ProjectNational Natural Science Foundation of China[41801232] ; Fundamental Research Funds for the Central Universities[2018QNA6011]
Funding OrganizationNational Natural Science Foundation of China ; Fundamental Research Funds for the Central Universities
WOS Research AreaChemistry ; Electrochemistry ; Instruments & Instrumentation
WOS SubjectChemistry, Analytical ; Electrochemistry ; Instruments & Instrumentation
WOS IDWOS:000473762500070
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Document Type期刊论文
Corresponding AuthorWang, Hongquan
Affiliation1.Zhejiang Univ, Coll Environm & Resource Sci, Inst Agr Remote Sensing & Informat Technol Applic, Hangzhou 310058, Zhejiang, Peoples R China
2.Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Key Lab Water Cycle & Related Land Surface Proc, Beijing 100101, Peoples R China
3.Nat Resources Serv Ctr, Dalian 116021, Peoples R China
Recommended Citation
GB/T 7714
Zhu, Luyao,Wang, Hongquan,Tong, Cheng,et al. Evaluation of ESA Active, Passive and Combined Soil Moisture Products Using Upscaled Ground Measurements[J]. SENSORS,2019,19(12):19.
APA Zhu, Luyao,Wang, Hongquan,Tong, Cheng,Liu, Wenbin,&Du, Benxu.(2019).Evaluation of ESA Active, Passive and Combined Soil Moisture Products Using Upscaled Ground Measurements.SENSORS,19(12),19.
MLA Zhu, Luyao,et al."Evaluation of ESA Active, Passive and Combined Soil Moisture Products Using Upscaled Ground Measurements".SENSORS 19.12(2019):19.
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