Unaccounted variability in NH3 agricultural sources detected by IASI contributing to European spring haze episode
Résumé
Ammonia (NH3), whose main source is agriculture, is an important gaseous precursor of atmospheric
particulate matter (PM). For the first time, we derived daily ammonia emissions using NH3 total columns
from the Infrared Atmospheric Sounding Interferometer (IASI) onboard Metop-A, at a relatively high spatial
resolution (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 European
reference 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 NH3
and PM10 surface concentrations and allows for a better comparison with independent measurements (in
terms of bias, root mean square error and correlation). This preliminary study suggest that there are good
promises for better quantifying NH3 emissions by atmospheric inversions.