Combining machine learning algorithms for bridging gaps in GRACE and GRACE Follow-On missions using ERA5-Land reanalysis

The Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GFO) missions have provided valuable data for monitoring global terrestrial water storage anomalies (TWSA) over the past two decades. However, the nearly one-year gap between these missions pose challenges for long-term TWSA me...

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Main Authors: Jaydeo K. Dharpure, Ian M. Howat, Saurabh Kaushik, Bryan G. Mark
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Science of Remote Sensing
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666017225000045
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author Jaydeo K. Dharpure
Ian M. Howat
Saurabh Kaushik
Bryan G. Mark
author_facet Jaydeo K. Dharpure
Ian M. Howat
Saurabh Kaushik
Bryan G. Mark
author_sort Jaydeo K. Dharpure
collection DOAJ
description The Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GFO) missions have provided valuable data for monitoring global terrestrial water storage anomalies (TWSA) over the past two decades. However, the nearly one-year gap between these missions pose challenges for long-term TWSA measurements and various applications. Unlike previous studies, we use a combination of Machine Learning (ML) methods—Random Forest (RF), Support Vector Machine (SVM), eXtreme Gradient Boosting (XGB), Deep Neural Network (DNN), and Stacked Long-Short Term Memory (SLSTM)—to identify and efficiently bridge the gap between GRACE and GFO by using the best-performing ML model to estimate TWSA at each grid cell. The models were trained using six hydroclimatic variables (temperature, precipitation, runoff, evapotranspiration, ERA5-Land derived TWSA, and cumulative water storage change), as well as a vegetation index and timing variables, to reconstruct global land TWSA at 0.5° grid resolution. We evaluated the performance of each model using Nash-Sutcliffe Efficiency (NSE), Pearson's Correlation Coefficient (PCC), and Root Mean Square Error (RMSE). Our results demonstrate test accuracy with area weighted average NSE, PCC, and RMSE of 0.51 ± 0.31, 0.71 ± 0.23, and 4.75 ± 3.63 cm, respectively. The model's performance was further compared across five climatic zones, with two previously reconstructed products (Li and Humphrey methods) at 26 major river basins, during flood/drought events, and for sea-level rise. Our results showcase the model's superior performance and its capability to accurately predict data gaps at both grid and basin scales globally.
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spelling doaj-art-67f7a388f9ca4022b9e6d0e194ab3bd82025-02-08T05:01:10ZengElsevierScience of Remote Sensing2666-01722025-06-0111100198Combining machine learning algorithms for bridging gaps in GRACE and GRACE Follow-On missions using ERA5-Land reanalysisJaydeo K. Dharpure0Ian M. Howat1Saurabh Kaushik2Bryan G. Mark3Byrd Polar and Climate Research Center, The Ohio State University, Columbus, 43210, USA; Corresponding author.Byrd Polar and Climate Research Center, The Ohio State University, Columbus, 43210, USA; School of Earth Sciences, The Ohio State University, Columbus, 43210, USAByrd Polar and Climate Research Center, The Ohio State University, Columbus, 43210, USA; School of Earth Sciences, The Ohio State University, Columbus, 43210, USA; School of Geography, Development & Environment, University of Arizona, Tucson, 85721, USAByrd Polar and Climate Research Center, The Ohio State University, Columbus, 43210, USA; Department of Geography, The Ohio State University, Columbus, 43210, USAThe Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GFO) missions have provided valuable data for monitoring global terrestrial water storage anomalies (TWSA) over the past two decades. However, the nearly one-year gap between these missions pose challenges for long-term TWSA measurements and various applications. Unlike previous studies, we use a combination of Machine Learning (ML) methods—Random Forest (RF), Support Vector Machine (SVM), eXtreme Gradient Boosting (XGB), Deep Neural Network (DNN), and Stacked Long-Short Term Memory (SLSTM)—to identify and efficiently bridge the gap between GRACE and GFO by using the best-performing ML model to estimate TWSA at each grid cell. The models were trained using six hydroclimatic variables (temperature, precipitation, runoff, evapotranspiration, ERA5-Land derived TWSA, and cumulative water storage change), as well as a vegetation index and timing variables, to reconstruct global land TWSA at 0.5° grid resolution. We evaluated the performance of each model using Nash-Sutcliffe Efficiency (NSE), Pearson's Correlation Coefficient (PCC), and Root Mean Square Error (RMSE). Our results demonstrate test accuracy with area weighted average NSE, PCC, and RMSE of 0.51 ± 0.31, 0.71 ± 0.23, and 4.75 ± 3.63 cm, respectively. The model's performance was further compared across five climatic zones, with two previously reconstructed products (Li and Humphrey methods) at 26 major river basins, during flood/drought events, and for sea-level rise. Our results showcase the model's superior performance and its capability to accurately predict data gaps at both grid and basin scales globally.http://www.sciencedirect.com/science/article/pii/S2666017225000045GRACEGap fillingMass changeMachine learningDeep learning
spellingShingle Jaydeo K. Dharpure
Ian M. Howat
Saurabh Kaushik
Bryan G. Mark
Combining machine learning algorithms for bridging gaps in GRACE and GRACE Follow-On missions using ERA5-Land reanalysis
Science of Remote Sensing
GRACE
Gap filling
Mass change
Machine learning
Deep learning
title Combining machine learning algorithms for bridging gaps in GRACE and GRACE Follow-On missions using ERA5-Land reanalysis
title_full Combining machine learning algorithms for bridging gaps in GRACE and GRACE Follow-On missions using ERA5-Land reanalysis
title_fullStr Combining machine learning algorithms for bridging gaps in GRACE and GRACE Follow-On missions using ERA5-Land reanalysis
title_full_unstemmed Combining machine learning algorithms for bridging gaps in GRACE and GRACE Follow-On missions using ERA5-Land reanalysis
title_short Combining machine learning algorithms for bridging gaps in GRACE and GRACE Follow-On missions using ERA5-Land reanalysis
title_sort combining machine learning algorithms for bridging gaps in grace and grace follow on missions using era5 land reanalysis
topic GRACE
Gap filling
Mass change
Machine learning
Deep learning
url http://www.sciencedirect.com/science/article/pii/S2666017225000045
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