Auxiliary dataset for study of 'High-Resolution Hydrological Data Assimilation using Future NGGM and MAGIC Satellite Gravity Products'

Terrestrial Water Storage (TWS) derived from the GRACE and GRACE-FO satellite gravity missions has been used in the past to improve the water storage representation of large-scale hydrological models through state-of-the-art sequential Data Assimilation (DA). These past experiments often used monthly gravity solutions to assess seasonal, interannual, and trend in global and regional TWS changes. Future gravity missions are designed to increase the temporal resolution of gravity solutions to 5 days, and enhance spatial resolution with smaller uncertainty than that of the GRACE-type gravity missions. These missions include NGGM of the Eurpean Space Agency (ESA), which is a single low-low satellite-to-satellite tracking (ll-SST) gravity mission in an inclined orbit, and MAGIC, which is a double ll-SST constellation that combines GRACE-C (planned to extend GRACE-FO by NASA/DLR) and ESA NGGM. Therefore, in this study, we will evaluate the added value of the NGGM and MAGIC missions in hydrological DA applications, especially in terms of spatio-temporal changes in the TWS, which is important to understand the role of their products in future operational hydrology-related monitoring and prediction systems. Our DA experiments are carried out using the daily 0.1-degree resolution W3RA water balance model, forced by the ERA5 climate input, during floods in the Brahmaputra and Danube River basins. As observations, 5-day GRACE-C, NGGM, and MAGIC TWS estimates are used within the DA. In this manner, we established a novel and efficient double-loop simulation/evaluation framework to perform 180 sets of candidate DA scenarios. All the synthetic data used in this study, as well as the output of this study, have been collected together and shared here. Specifically, this includes (1) shape files of Danube and Brahmaputra river basins, which have been partitioned into several smaller sub basins using five DA unit cell options; (2) synthetic 5-day global gravity products in terms of 0.5$^{\circ}$ gridded EWH for GRACE-C, NGGM, and MAGIC from 1995-2006, which has been filtered using six filtering options; (3) synthetic 5-day global gravity products of the truth from 1995-2006, in terms of 0.5$^{\circ}$ gridded TWS; (4) open-loop model simulations of TWS for 2003-2006 at a resolution of 1-day and 0.1$^\circ$; (5) 180 sets of DA results from 2003-2006 at a resolution of 1-day and 0.1$^\circ$; (6) evaluation results of the 180 sets of experiments in terms of KGE and NSE at a resolution of 0.5$^\circ$; (7) regional mask files in terms of 0.1$^\circ$ and 0.5$^\circ$. All the figures demonstrated in the paper can be reproduced with the data provided. A majority of the data is formated with HDF5, which has a self-description built in for the conveniece of users.