Health and ecosystem impacts of O₃ generally occur when O₃ concentrations are highest, but most air quality models underestimate peak O₃. We derived European NO_x emissions based on satellite NO₂ column data and evaluated the impact on model-simulated NO₂ and ozone. We show that a simulation with satellite-derived NO_x emissions leads to better agreement with independent in situ observations of surface NO₂ and O₃, which helps to reduce the model underestimations of peak ozone concentrations.