Mapping the 3D distribution of oceanic nitrate is challenging. We developed a continual-learning-based multilayer perceptron, integrating prior knowledge from numerical models and BGC-Argo validation to reconstruct a pan-European 3D nitrate field from 2010 to 2023 (0–2000 m depth, monthly, 0.25° horizontal resolution) using sea surface environmental features. This dataset helps bridge observational gaps and enhances understanding of the ocean's interior environment.