Downscaled GRACE-FO TWSA for Greece

The dataset comprises GRACE-FO downscaled Total Water Storage Anomalies, at 0.1 degrees spatial resolution. Units are in mm with reference the 2004 - 2009 period. Abstract: A downscaling framework for coarse resolution Gravity Recovery and Climate Experiment (GRACE) Total Water Storage Anomaly (TWSA) data is described, exploiting the observations of precipitation from the Global Precipitation Measurement (GPM) mission, using the Integrated Multisatellite Retrievals for GPM (IMERG). Considering that the major driving force for changes in TWS is precipitation, we tested our hypothesis that coarse resolution, i.e., 1◦, GRACE TWSA can be effectively downscaled to 0.1◦ using GPM IMERG data. The algorithm for the downscaling process comprises the development of a regression equation at the coarse resolution between the GRACE and GPM IMERG data, which is then applied at the finer resolution with a subsequent residual correction procedure. An ensemble of GRACE data from three processing centers, i.e., GFZ, JPL and CSR, was used for the time period from June 2018 until March 2021. To verify our downscaling methodology, we applied it with GRACE data from 2005 to 2015, and we compared it against modeled TWSA from two independent datasets in the Thrace and Thessaly regions in Greece for the same period and found a high performance in all examined metrics. Our research indicates that the downscaled GRACE observations are comparable to the TWSA estimated with hydrological modeling, thus highlighting the potential of GRACE data to contribute to the improvement of hydrological model performance, especially in ungauged basins.本数据集包含空间分辨率为0.1度的降尺度重力恢复与气候实验后续卫星（GRACE-FO）总水储量异常（Total Water Storage Anomalies, TWSA）数据，单位为毫米，基准参考期为2004年至2009年。 摘要：本文阐述了一种针对低分辨率重力恢复与气候实验（GRACE）总水储量异常（TWSA）数据的降尺度框架，该框架利用全球降水测量（GPM）任务的降水观测数据，具体采用GPM多卫星综合反演产品（IMERG）。鉴于降水是总水储量（Total Water Storage, TWS）变化的主要驱动因子，我们验证了如下假设：借助GPM IMERG数据，可将1度分辨率的GRACE TWSA数据有效降尺度至0.1度分辨率。该降尺度流程的算法包括先在低分辨率尺度下构建GRACE与GPM IMERG数据间的回归方程，随后将该方程应用于高分辨率尺度，并辅以后续的残差校正步骤。本研究使用了2018年6月至2021年3月期间，来自GFZ、JPL和CSR三个数据处理中心的GRACE集合数据。为验证该降尺度方法的有效性，我们将其应用于2005年至2015年的GRACE数据，并与同期希腊色雷斯和色萨利地区两个独立数据集的模拟TWSA进行对比，结果显示所有评估指标均表现优异。本研究表明，降尺度后的GRACE观测数据与水文模型估算的TWSA具有可比性，由此凸显了GRACE数据在提升水文模型性能方面的应用潜力，尤其在无资料流域中。