This dataset presents high-resolution (0.25°) terrestrial water storage anomalies (TWSA) derived through a novel iterative downscaling method applied to GRACE satellite observations. Unlike traditional approaches that rely heavily on hydrometeorological inputs and often miss long-term trends, this method preserves nearly all of the original GRACE signal content. The downscaled TWSA demonstrates enhanced agreement with in-situ groundwater measurements, showing higher correlation in over 63% of global wells and reduced RMSE in more than 83%. Additionally, it maintains a strong correlation (average r = 0.98) with original GRACE data across all global 1° land grids, outperforming existing downscaling products.