Beyond HCHO/NO₂: Global Daily Maps of Net Ozone Production Rates and Sensitivities Constrained by Satellite Observations (2005–2023)

Abstract. Previous studies on net ozone production rates (PO₃) and their sensitivities to precursors relied on limited in-situ data, often coarse and uncertain chemical transport models (CTMs), and ozone indicators like the formaldehyde-to-nitrogen dioxide ratio (FNR). However, FNR fails to fully capture PO₃'s complex relationships with pollution, light, and water vapor. To address this, we refine the satellite-based PO₃ product from Souri et al. (2025) with key advancements: (i) a deep neural network to parametrize high-dimensional non-linear ozone chemistry without the need for empirical linearization of atmospheric conditions, (ii) incorporation of water vapor, (iii) improved error characterization, and (iv) the application of a finer CTM to dynamically convert column retrievals into near-surface mixing ratios. Our PO₃ sensitivity maps surpass traditional FNR-based assessments by quantifying sensitivity magnitudes – factoring in photolysis rates and water vapor – with greater spatial information. Our PO₃ product with its high horizontal coverage will advance our understanding of the drivers of locally-produced ozone pollution, but only at a single snapshot per day. Specifically, our new product provides daily near-clear sky PO₃ and sensitivity maps using bias-corrected OMI (2005–2019, 0.25° × 0.25°) and TROPOMI (2018–2023, 0.1° × 0.1°), with values aligning within 10 %. High PO₃ rates (>8 ppbv/hr) appear in urban and biomass-burning regions under strong photochemical activity, including during a heatwave in the northeastern U.S. Photolysis rates are the dominant factor dictating the seasonality of PO₃ magnitudes and sensitivities.