Global, regional and national trends of atmospheric ammonia derived from a decadal (2008–2018) satellite record

Excess atmospheric ammonia (NH₃) leads to deleterious effects on biodiversity, ecosystems, air quality and health, and it is therefore essential to monitor its budget and temporal evolution. Hyperspectral infrared satellite sounders provide daily NH₃ observations at global scale for over a decade. Here we use the version 3 of the Infrared Atmospheric Sounding Interferometer (IASI) NH₃ dataset to derive global, regional and national trends from 2008 to 2018. We find a worldwide increase of 12.8 ± 1.3 % over this 11-year period, driven by large increases in east Asia (5.80 ± 0.61% increase per year), western and central Africa (2.58 ± 0.23 % yr⁻¹), North America (2.40 ± 0.45 % yr⁻¹) and western and southern Europe (1.90 ± 0.43 % yr⁻¹). These are also seen in the Indo-Gangetic Plain, while the southwestern part of India exhibits decreasing trends. Reported national trends are analyzed in the light of changing anthropogenic and pyrogenic NH₃ emissions, meteorological conditions and the impact of sulfur and nitrogen oxides emissions, which alter the atmospheric lifetime of NH₃. We end with a short case study dedicated to the Netherlands and the 'Dutch Nitrogen crisis' of 2019. (paper)