Groundwater Storage Changes within Europe: A Constrained Bayesian Integration of GRACE(-FO) Data into the W3RA Model

his dataset provides monthly estimates of groundwater storage change (GWS) across Europe at an effective spatial resolution of approximately 10 km, generated using an extended Constrained Bayesian (ConBay) data integration framework.The ConBay framework integrates satellite gravimetric observations from GRACE (2003–2017) and GRACE-FO (2018–present) with outputs from the W3RA hydrological model, while additionally constraining surface soil moisture states using independent observations from the ESA Climate Change Initiative (ESA CCI) soil moisture product (v09.1). This multi-source constraint improves the physical consistency between modeled and observed terrestrial water storage components and reduces equifinality in groundwater partitioning.To ensure spectral consistency, W3RA total water storage fields are transformed into the spectral domain and filtered using GRACE-consistent operators prior to assimilation. After Bayesian updating, residual components are reintroduced to enable physically coherent spatial downscaling of terrestrial water storage changes. ESA CCI soil moisture observations are incorporated as an independent constraint on surface soil moisture variability, improving consistency between surface and subsurface water storage dynamics.The resulting GWS estimates preserve the large-scale information content of GRACE while resolving sub-basin to regional-scale groundwater variability. Validation against in-situ groundwater level observations demonstrates improved representation of groundwater dynamics compared to existing gravity-based products, particularly in regions with complex hydrogeology and strong land–atmosphere coupling.Key characteristicsSpatial coverage: EuropeSpatial resolution: ~10 kmTemporal resolution: MonthlyTime span: 2003–present (GRACE and GRACE-FO eras)Variable: Groundwater storage change (GWS)Units: [meter equivalent water height]Constraints: GRACE/GRACE-FO terrestrial water storage change; ESA CCI surface soil moistureIntended useThis dataset is intended for research applications including continental-scale groundwater monitoring, hydro-climatic variability and drought assessment, model evaluation, and digital-twin development. Users should consider the intrinsic spatial smoothing of GRACE observations and the uncertainty characteristics provided with the dataset.CitationFor the technical details, users of this dataset are requested to cite the associated publication "Exploring the Dynamics of Deep Stored Water Resources within Europe by Developing a 10-km resolution Groundwater Estimate for a Digital Twin of the Terrestrial Water Cycle".For the dataset itself, please cite the Figshare information.

本数据集提供欧洲全域地下水储量变化（Groundwater Storage Change, GWS）的月度估算结果，有效空间分辨率约为10 km，采用扩展约束贝叶斯（Constrained Bayesian, ConBay）数据融合框架生成。
该ConBay框架将GRACE（2003–2017年）与GRACE-FO（2018年至今）的卫星重力观测数据，与W3RA水文模型的输出结果进行融合，同时额外利用欧洲空间局气候变化倡议（ESA Climate Change Initiative, ESA CCI）土壤湿度产品（v09.1）的独立观测数据约束地表土壤湿度状态。
这种多源约束机制提升了模拟与观测的陆地水储量组分间的物理一致性，同时减少了地下水分配过程中的多解性。
为确保频谱一致性，在数据同化前，需将W3RA的总水储量场转换至频谱域，并使用与GRACE匹配的算子进行滤波处理。经贝叶斯更新后，重新引入残差分量以实现陆地水储量变化的物理一致性空间降尺度。
ESA CCI土壤湿度观测被用作地表土壤湿度变化的独立约束项，进一步提升了地表与地下水储量动态的一致性。
最终得到的GWS估算结果保留了GRACE的大尺度信息含量，同时可分辨次流域至区域尺度的地下水变化特征。通过与原位地下水位观测数据的验证表明，相较于现有的基于重力的产品，该数据集能够更精准地刻画地下水动态，尤其在复杂水文地质条件以及陆气耦合作用强烈的区域。

核心特征：
空间覆盖范围：欧洲全域
空间分辨率：约10 km
时间分辨率：月度
时间跨度：2003年至今（覆盖GRACE与GRACE-FO观测时段）
核心变量：地下水储量变化（GWS）
单位：[米等效水高]
约束数据源：GRACE/GRACE-FO陆地水储量变化；ESA CCI地表土壤湿度

预期用途：
本数据集适用于大陆尺度地下水监测、水文气候变异性与干旱评估、模型验证以及陆地水循环数字孪生开发等研究场景。使用者需考虑GRACE观测固有的空间平滑效应，以及数据集附带的不确定性特征。

引用说明：
如需获取技术细节，请引用相关学术论文《Exploring the Dynamics of Deep Stored Water Resources within Europe by Developing a 10-km resolution Groundwater Estimate for a Digital Twin of the Terrestrial Water Cycle》。
如需引用本数据集本体，请引用Figshare平台的相关数据集信息。