The effects of the Syrian civil war on atmospheric ammonia asseen from IASI

International audience ; The Syrian civil war started a decade ago, in March 2011, causing dramatic social, political, economicand environmental consequences over the whole area of Syria and nearby countries. Agriculture inparticular suffered massively, which affected the economy directly since the agricultural sector makes upto 26% of the gross domestic product (GDP) of the country. Several studies used satellite-retrieved dataand imagery to examine the spatio-temporal changes in the region, for the period of the conflict.In this study we investigate the impacts of the Syrian civil war on atmospheric ammonia (NH?) emittedfrom industrial and agricultural activities during the 2008-2019 period. Our analyses are based on theNH? measurements from the IASI instruments on board the Metop satellites. Firstly, land-use changesand decrease of agriculture-emitted ammonia are explored over the country, and especially in the north-eastern part of Syria that has suffered from the conflict that included ISIS and Kurdish fighters. We alsoinvestigate the changes in atmospheric NH? at an ammonia production plant, which activities have beensuspended due to several conflict-related events. We show that the NH? columns retrieved from IASI aredirectly affected by the war, and that periods of intense conflict and siege are reflected in lower NH?concentrations, which are not driven by meteorology. The interpretation of the identified changes inatmospheric NH? are supported by different datasets: NO? columns from GOME-2, satellite imagery,and MODIS land cover type, reanalysis data from ECMWF (ERA5) to look at meteorological factors thatmay affect atmospheric ammonia concentrations, as well as the burned area from the Aqua/Terracombined MODIS product to check for fires.