Top-down estimation of NH3 emissions and related deposition in LOTOS-EUROS

Monitoring NH3 concentrations and deposition remains one of the largest challenges to date. Satellite observations of atmospheric NH3 may help us fill in observational and knowledge gaps.

Recent observations of the Cross-track Infrared Sounder (CrIS) provides us with daily, global NH3 total columns. In this study, we assimilate these observations in the LOTOS-EUROS regional chemical transport model using an Ensemble-Kalman approach.

We focus on western Europe (Germany, the Netherlands, Belgium), one of the main European hotspots of atmospheric NH3. Within this domain, we identified regions with the largest model-satellite discrepancies. These regions are used as cornerstones for optimization of the settings of the Ensemble-Kalman filter. Consequently, top-down estimates of NH3 emissions are obtained and compared to the initially used NH3 database. Finally, we looked at the impacts of these updated NH3 emissions on our modelled Nr deposition fields.