Three-hourly fused atmospheric de-aliasing product for GRACE-FO based on ERA5 and CRA-40 reanalysis (2019–2021)

This repository provides a three-hourly fused atmospheric de-aliasing dataset tailored for GRACE and GRACE Follow-On gravity field processing for the period 2019–2021. The product represents global atmospheric mass variations that can be used as background models to reduce temporal aliasing errors in monthly gravity field solutions. The fused fields are based on two atmospheric reanalysis datasets, ERA5 and CRA-40. The fusion is performed at the normal-equation level between the vertically integrated fields and their spherical harmonic representation using Helmert variance component estimation, yielding a fused solution that balances the contributions of the two input datasets. Data are organised as monthly ZIP archives, each corresponding to one calendar month and named by year and month. Within each archive, daily ASCII files contain the spherical harmonic coefficients for all three-hourly epochs of that day (00, 03, 06, 09, 12, 15, 18, and 21 UTC), in a format that can be directly used in GRACE/GRACE-FO gravity field processing workflows. The dataset is intended as an alternative atmospheric de-aliasing product that can be used alongside standard models such as GFZ AOD1B RL07 to assess the impact of atmospheric background modelling choices on GRACE/GRACE-FO gravity solutions. This study is also supported by the Fundamental Research Funds for the Central Universities.