Assessment of GRACE/GRACE Follow-On Terrestrial Water Storage Estimates Using an Improved Forward Modeling Method: A Case Study in Africa

Zhou, Hao; Dai, Min; Wang, Penghui; Wang, Min; Tang, Lu; Xu, Siyou; Luo, Zhicai

doi:10.3389/feart.2021.796723

Cited by 5 publications

(3 citation statements)

References 49 publications

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“…The forward modeling technique is utilized to restore the leakage signal in the mass field of each available month by iteration (Chen et al, 2015). In the forward modeling technique, the model undergoes iterative updates until the difference between the filtered model and the filtered observation is minimized below a specified threshold (Doumbia et al, 2020;Zhou et al, 2022). The final TWS changes with three methods and the two mascon products are shown in Figure 9.…”

Section: Validation Of the Improved Mass Changesmentioning

confidence: 99%

Improving mass change estimation in Panama with the GRACE/GFO gravity field using the variational mode decomposition

Jian

Yao

2023

Front. Earth Sci.

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In this study, we aim to estimate the mass changes in Panama using the Gravity Recovery and Climate Experiment level-2 products, which are formed as spherical harmonic coefficients and limited by stripe noise. The empirical de-striping method and the temporal filter achieved by empirical mode decomposition can be used to reveal the signals but are still limited in signal reservation and noise reduction. To this end, we put forward a novel efficient strategy that uses the variational mode decomposition algorithm to filter the time series of each SHC separately. Based on the two reliable mascon products and in situ short-term groundwater observations, various comparisons in spatial, spectral, and temporal domains are implemented. In addition, the SNR (signal-to-noise ratio) index and the three-cornered hat method are adopted for assessment. The main results and conclusions are as follows: 1) Our filter outperforms the two previous methods with the best SNR (2.14) and the lowest Panama regional uncertainty (70 mm) for all available months. 2) Our estimate of the basin groundwater storage is closest to one of the groundwater observations with the maximum correlation coefficient (0.72, p<0.05). This result suggests that our method seems to detect small-scale mass signals that are undetectable in the two mascon products. Our work provides a reference for studying the mass change of small-scale basins in low latitudes.

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Section: Validation Of the Improved Mass Changesmentioning

confidence: 99%

Improving mass change estimation in Panama with the GRACE/GFO gravity field using the variational mode decomposition

Jian

Yao

2023

Front. Earth Sci.

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“…Compared with the DO/60 (~333 km) truncation, the truncation of DO/96 (~208 km) simultaneously leads to a high numerical spatial resolution and potentially involves more potential high-frequency error from high-degree SHCs in the results. This residual noise may lead to unpredictable noise accumulation in the iteration of the forward modeling technique [75]. However, our concern is with the basin average signal rather than the spatial detail variation in the mass field.…”

Section: Limitation and Outlookmentioning

confidence: 99%

A GRACE/GFO Empirical Low-Pass Filter to Extract the Mass Changes in Nicaragua

Jian

Wang

et al. 2023

Remote Sensing

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Among the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-on temporal gravity products, the north–south stripe noise in the spherical harmonic coefficient (SHC) products contaminates the inversion of the Earth’s mass field. In this study, GRACE SHC products are adopted to estimate the mass changes in Nicaragua. To improve this estimation, we propose an empirical low-pass filter to suppress stripe noise. After only using our filter, the Nicaragua regional uncertainty diminishes from 123.26 mm to 69.11 mm, and the mean signal-to-noise ratio of all available months (2002–2021) improves from 1.67 to 1.8. Subsequently, our filter is employed to estimate the basin terrestrial water storage (TWS) change in Nicaragua. In the end, TWS change estimations are compared with various observations such as mascon products, hydrological models, and in situ groundwater observation. The main conclusions are as follows: (1) After using the wavelet coherent analysis, there is a negative resonance between TWS and the climate factor (El Nino–Southern Oscillation) with a period of 2~4 years; (2) The significant ~3.8-year periodic signal in groundwater storage change estimation is contributed by GRACE aliasing error. Our work can provide new knowledge and references for mass change in small areas.

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“…Many approaches have been proposed for precise inversion of TWS anomaly on a regional scale. However, most research concentrated on regions or river basins like the Amazon, Greenland, Indus, Antarctica, Yangtze River, Tibetan Plateau, Congo, Nile, and so on [22][23][24][25][26][27][28][29][30][31]. Those regions are characteristic of larger areas (>10 6 km 2 ) or stronger signals attributed to mass changes.…”

Section: Introductionmentioning

confidence: 99%

The Extraction of Terrestrial Water Storage Anomaly from GRACE in the Region with Medium Scale and Adjacent Weak Signal Area: A Case for the Dnieper River Basin

Zhang,

Bian,

et al. 2024

Remote Sensing

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The accuracy of estimating changes in terrestrial water storage (TWS) using Gravity Recovery and Climate Experiment (GRACE) level-2 products is limited by the leakage effect resulting from post-processing and the weak signal magnitude in adjacent areas. The TWS anomaly from 2003 to 2016 in the Dnieper River basin, with characteristics of medium scale and an adjacent weak TWS anomaly area, are estimated in this work. Two categories of leakage error repair approaches (including forward modeling, data-driven, single, and multiple scaling factor approaches) are employed. Root mean square error (RMSE) and Nash–Sutcliffe Efficiency (NSE) are used to evaluate the efficiency of approaches. The TWS anomaly inverted by the forward modeling approach (FM) is more accurate in terms of RMSE 3.04 and NSE 0.796. We compared single and multiple scaling approaches for the TWS anomaly and found that leakage signals mostly come from semi-annual terms. From the recovered results demonstrated in the spatial domain, the South of Dnieper River basin is more sensitive to the leakage effect because of it is adjacent to a weak hydrological signal region near the Black Sea. Further, comprehensive climate insights and physical mechanisms behind the TWS anomaly were confirmed. The temperate continental climate of this river basin is shown according to the variation in TWS anomaly in the spatial domain. Snowmelt plays a significant role in the TWS anomaly of the Dnieper River basin, following the precipitation record and the 14-year temperature spatial distribution for February. We compared single and multiple scaling approaches for the TWS anomaly and found that leakage signals mostly come from semi-annual terms.

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Assessment of GRACE/GRACE Follow-On Terrestrial Water Storage Estimates Using an Improved Forward Modeling Method: A Case Study in Africa

Cited by 5 publications

References 49 publications

Improving mass change estimation in Panama with the GRACE/GFO gravity field using the variational mode decomposition

Improving mass change estimation in Panama with the GRACE/GFO gravity field using the variational mode decomposition

A GRACE/GFO Empirical Low-Pass Filter to Extract the Mass Changes in Nicaragua

The Extraction of Terrestrial Water Storage Anomaly from GRACE in the Region with Medium Scale and Adjacent Weak Signal Area: A Case for the Dnieper River Basin

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