Unaccounted variability in NH₃ agricultural sources detected by IASIcontributing to European spring haze episode

International audienceAmmonia (NH3), whose main source is agriculture, is an important gaseous precursor of atmosphericparticulate matter (PM). For the first time, we derived daily ammonia emissions using NH3 total columnsfrom the Infrared Atmospheric Sounding Interferometer (IASI) onboard Metop-A, at a relatively high spatialresolution (grid-cell of 0.5° x 0.5°). During the European spring haze episode of March 2014 8th to 15th,IASI reveals NH3 total column magnitudes highlighting higher NH3 emissions over Central Europe(especially over Germany, Czech Republic and eastern France) from the ones provided by the Europeanreference EMEP inventory. These ammonia emissions exhibit in addition a large day-to-day variability,certainly due to spreading practices.The increase of NH3 emissions in the model, that reaches +300% locally, leads to an increase of both NH3and PM10 surface concentrations and allows for a better comparison with independent measurements (interms of bias, root mean square error and correlation). This preliminary study suggest that there are goodpromises for better quantifying NH3 emissions by atmospheric inversions