Long-term Spatial Estimates and Trends of Wet Deposition of Sulfate, Nitrate, and Ammonium over Europe, North America, and East Asia

A dual-loss U-Net framework was developed to estimate the monthly wet deposition of three inorganic species, namely sulfate (SO₄²⁻), nitrate (NO₃⁻), and ammonium (NH₄⁺) at 0.25° resolution across Europe, North America, and East Asia from 2005/2008 to 2024. The model combines station-based observations as magnitude constraints with a GMI-simulated spatial ranking loss, together with satellite precursor columns, precipitation, aerosol optical depth, and meteorological predictors. In station-based 10-fold cross-validation, the pooled monthly R² values are 0.73, 0.65, and 0.80, and the annual R² values are 0.89, 0.84, and 0.86 for SO₄²⁻, NO₃⁻, and NH₄⁺, respectively. This long-term, multi-species wet deposition dataset is publicly available and can support research on acidification, eutrophication, ecosystem exposure, and the evaluation of emission-control effectiveness.