Unaccounted variability in NH sub(3) agricultural sources detected by IASI contributing to European spring haze episode

Ammonia (NH sub(3)), whose main source in the troposphere is agriculture, is an important gaseous precursor of atmospheric particulate matter (PM). We derived daily ammonia emissions using NH sub(3) total columns measured from the Infrared Atmospheric Sounding Interferometer (IASI) on board Metop-A, at a relatively high spatial resolution (grid cell of 0.5 degree 0.5 degree ). During the European spring haze episodes of 24-31 March 2012 and 8-15 March 2014, IASI reveals NH sub(3) total column magnitudes highlighting higher NH sub(3) emissions over central Europe (especially over Germany, Czech Republic, and eastern France) from the ones provided by the European reference European Monitoring and Evaluation Programme inventory. These ammonia emissions exhibit in addition a large day-to-day variability, certainly due to spreading practices. The increase of NH sub(3) emissions in the model, that reaches +300% locally, leads to an increase of both NH sub(3) and PM sub(2.5) surface concentrations and allows for a better comparison with independent measurements (in terms of bias, root-mean-square error, and correlation). This study suggests that there are good prospects for better quantifying NH sub(3) emissions by atmospheric inversions. Key Points * Strong potential of IASI for deducing NH sub(3) daily emissions * High NH sub(3) emissions revealed over central Europe * Strong impact of NH sub(3) emissions on pollution particle formation