Uncertainty analysis of SVD-based spaceborne far–red sun-induced chlorophyll fluorescence retrieval using TanSat satellite data

Li, Shilei; Gao, Maofang; Li, Zhao-Liang; Duan, Si‐Bo; Leng, Pei

doi:10.1016/j.jag.2021.102517

Cited by 4 publications

(4 citation statements)

References 33 publications

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“…This may be due to the accuracy of the SVD algorithm itself. This could also be related to the parameter settings or the training dataset selection [28,29]. How to select the optimal parameters and training dataset for SVD remains a challenging problem.…”

Section: Discussionmentioning

confidence: 99%

Using High-Frequency PAR Measurements to Assess the Quality of the SIF Derived from Continuous Field Observations

et al. 2022

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Fluctuations in illumination are one of the major sources for SIF retrieval errors during temporal continuous field measurements. In this study, we propose a method for evaluating the quality of SIF based on simultaneous measurements of photosynthetically active radiation (PAR), which are acquired using a quantum sensor at a sampling frequency higher than that obtained using spectral measurements. The proposed method is based on the coefficient of variation (known as relative standard deviation) of the high-frequency PAR during a SIF measurement to determine the quality of the SIF value. To evaluate the method, spectral and PAR data of a healthy maize canopy were collected under various illumination conditions, including clear, cloudy, and rapidly fluctuating illumination. The SIF values were retrieved by 3FLD, SFM, and SVD. The results showed that SFM and 3FLD were sensitive to illumination stability. The determination coefficients (R2) between PAR and SIF extracted by SFM and 3FLD were higher than 0.8 on clear and cloudy days and only approximately 0.48 on the day with rapidly fluctuating illumination. By removing the unqualified data using the proposed method, the R2 values of SFM and 3FLD on the day of rapidly fluctuating illumination significantly increased to 0.72. SVD was insensitive to illumination stability. The R2 values of SVD on days with clear, cloudy, and rapidly fluctuating illumination were 0.73, 0.76, and 0.61, respectively. By removing the unqualified data, the R2 values of SVD were increased to 0.66 on the day with rapidly fluctuating illumination. The results indicated that the quality assessment method based on high-frequency PAR data can eliminate the incorrect SIFs due to unstable illumination. The method can be used to extract more accurate and reliable SIF datasets from long-term field observations for the study of the relationship between SIF and vegetation photosynthesis.

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Section: Discussionmentioning

confidence: 99%

Using High-Frequency PAR Measurements to Assess the Quality of the SIF Derived from Continuous Field Observations

et al. 2022

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“…Powerful matrix analysis techniques include principal component analysis (PCA) ( Sun and Axhausen, 2016 ), singular value decomposition (SVD) ( Chen et al, 2018 ), and non-negative matrix decomposition ( Huang et al, 2013 ). In most cases, PCA problems can be transformed into SVD problems, and using SVD is usually more stable than using PCA directly as SVD avoids part of the accuracy loss in covariance calculations ( Lipovetsky, 2009 ; Li et al, 2021 ). In addition, SVD decomposes a data matrix into uncorrelated variables, revealing intrinsic structures in multi-dimensional data ( Jolliffe and Cadima, 2016 ).…”

Section: Methodsmentioning

confidence: 99%

COVID-19 lockdown introduces human mobility pattern changes for both Guangdong-Hong Kong-Macao greater bay area and the San Francisco bay area

Zhong

Zhou

Gao

et al. 2022

International Journal of Applied Earth Observation and Geoinfor

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“…Hence, by assuming that the SIF and reflectance were polynomials or other appropriate mathematical functions of wavelengths, the Spectral Fitting Methods (SFM), proposed by Meroni et al [28], utilized a set of contiguous channels to estimate SIF. Apart from these FLD-based algorithms, statistical methods based on singular vector decomposition (SVD) or principal component analysis (PCA) were proposed to enhance FLD SIF retrieval from satellites [29,30] but were applied to extract ground-based SIF [31].…”

Section: F760toc Retrievalmentioning

confidence: 99%

Assessing the Potential of Downscaled Far Red Solar-Induced Chlorophyll Fluorescence from the Canopy to Leaf Level for Drought Monitoring in Winter Wheat

Lin

Shen

et al. 2022

Remote Sensing

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Solar-induced chlorophyll fluorescence (SIF) from ground, airborne, and satellite-based observations has been increasingly used in drought monitoring recently due to its close relationship with photosynthesis. SIF emissions respond rapidly to droughts, relative to the widely used vegetation indices (VIs), thus indicating their potential for early drought monitoring. The response of SIF to droughts can be attributed to the confounding effects of both the physiology and canopy structure. In order to reduce the reabsorption and scattering effects, the total emitted SIF (SIFtot) was proposed and served as a better tool to estimate GPP compared with the top-of-canopy SIF (SIFtoc). However, the response time and response magnitude of SIFtot to droughts and its relationships with the environmental parameters and soil moisture (SM) (i.e., the knowledge of drought monitoring using SIFtot) remains unclear. Here, the continuous ground data of F760toc (SIFtoc at 760 nm) from a nadir view that was downscaled to F760tot (SIFtot at 760 nm), NIRv, and the NDVI, SM, meteorological, and crop growth parameters were measured from four winter wheat plots with different intensities of drought (well-watered, moderate drought, severe drought, and extreme drought) over 2 months. The results indicated that F760tot was more closely correlated with the SM than the VIs at short time lags but weaker at longer time lags. The daily mean values of F760tot and NIRv were able to distinguish the differences between different drought levels, and F760tot responded quickly to the onset of drought, especially for the moderate drought intensity. These findings demonstrated that F760tot has potential for early drought monitoring and may contribute to mitigating the risk of agricultural drought.

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Uncertainty analysis of SVD-based spaceborne far–red sun-induced chlorophyll fluorescence retrieval using TanSat satellite data

Cited by 4 publications

References 33 publications

Using High-Frequency PAR Measurements to Assess the Quality of the SIF Derived from Continuous Field Observations

Using High-Frequency PAR Measurements to Assess the Quality of the SIF Derived from Continuous Field Observations

COVID-19 lockdown introduces human mobility pattern changes for both Guangdong-Hong Kong-Macao greater bay area and the San Francisco bay area

Assessing the Potential of Downscaled Far Red Solar-Induced Chlorophyll Fluorescence from the Canopy to Leaf Level for Drought Monitoring in Winter Wheat

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