Ammonia emission estimates using CrIS satellite observations over Europe

Over the past century ammonia (NH ₃) emissions have increased with the growth of livestock and fertilizer usage. The abundant NH ₃ emissions lead to secondary fine particulate matter (PM2.5) pollution, climate change, reduction in biodiversity and affects human health. Up-to-date and spatially and temporally resolved information of NH ₃ emissions is essential to better quantify its impact. In this study we applied the existing DECSO (Daily Emissions Constrained by Satellite Observations) algorithm to NH ₃ observations from the Cross-track Infrared Sounder (CrIS) to estimate NH ₃ emissions. Because NH ₃ in the atmosphere is influenced by Nitrogen Oxides (NO _x), we implemented DECSO to estimate NO _x and NH ₃ emissions simultaneously. The emissions are derived over Europe for 2020 on a spatial resolution of 0.2° x 0.2° using daily observations from both CrIS and TROPOMI (on the Sentinel 5p satellite). Due to the sparseness of daily satellite observations of NH ₃, monthly emissions of NH ₃ are reported. The total NH ₃ emissions derived from observations are about 8 Tg/year with a precision of about 0.2 % over the European domain. The comparison of the satellite-derived NH ₃ emissions from DECSO with independent bottom-up inventories and in-situ observations indicates a consistency in terms of magnitude on the country totals, the results also being comparable regarding the temporal and spatial distributions.