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ROMFORSK-Program for romforskning

Quantification of Global Ammonia Sources constrained by a Bayesian Inversion Technique

Alternative title: Kvantifisering av globale ammoniakkilder ved bruk av Bayesiansk inversjonsteknikk

Awarded: NOK 7.5 mill.

Project Number:


Project Period:

2018 - 2023

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Nitrogen is a basic component of life and it is present both in proteins and DNA. Its basic chemical form in nature is the non-reactive gaseous N2. However, in the 20th Century humans converted N2 into more reactive forms. Today, NH3 (ammonia) sustains life and almost 40% of the global population owes its life to NH3 through the use of fertilisers' in food production. Though, implications of ammonia for population and environment have received a lot of attention in the last decades. On one hand, its presence in the atmosphere in low concentrations is beneficial as it makes the rain less acidic by neutralising sulphuric acid aerosols. On the other hand, increased emissions of NH3 result in reactions with sulphuric and nitric acids contributing 30%-50% to the total PM2.5 and PM10 mass. Enhanced production of ammonium aerosols can cause premature mortality as they penetrate human respiratory system and deposit in the lungs. Furthermore, ammonium aerosols affect the Earth?s radiative balance, both directly by scattering incoming radiation and indirectly as cloud condensation nuclei causing a positive climate feedback (warming). Despite its importance, NH3 is one of the most poorly quantified gases with a limited number of continuous ammonia measurements in Europe, America or Asia. However, the lack of observations is covered by satellites and nowadays satellite algorithms are advanced enough to provide daily global concentrations of atmospheric NH3. We use the existing knowledge of Lagrangian dispersion modelling and Bayesian inversion in NILU accompanied by continuous and satellite measurements to quantify emissions of NH3 in Europe, Southeastern Asia and USA since 2013. The latter constitute over 90% of global emissions. The optimised fluxes of NH3 are studied and the impact to the environment and the population is examined. The methodology is designed to maximize the utility of empirical data for the least understood aspects and use models for source identification, which cannot be inferred from measurements alone.

- Spatiotemporal calculation of NH3 lifetimes since 2008. - Calculation of chemical loss in Eulerian model LMDz-OR-INCA - Model development to considered chemical loss of NH3 due to reaction with HNO3 and H2SO4. - Development of a new inversion algorithm suitable for use of satellite observations. - Development of a 1D box-model for the calculation of NH3 fluxes based on IASI NH3 and model lifetimes. - Calculation of NH3 fluxes over Europe during COVID-19 lockdowns based on inverse modelling and satellite observations. - Evolution of NH3 fluxes over Europe since 2013 based on inverse modelling and satellite observations. - Evolution of NH3 fluxes over USA since 2013 based on inverse modelling and satellite observations.] - Evolution of NH3 fluxes over Southeastern Asia since 2013 based on inverse modelling and satellite observations.

Ammonia (NH3) has been proved very important for humans mainly because it sustains life as a major component in the global nitrogen cycle. Over 40% of the global population owe their lives to the industrial synthesis of ammonia for fertilizer production (Haber-Bosch process). However, ammonia has received a lot of attention in the recent past due to its major consequences for the population and the environment through secondary formation of PM2.5 after heterogeneous reactions with abundant atmospheric constituents. The global rise of population has almost doubled ammonia emissions since the 70s, as a result of both artificial and natural emissions. In the present proposal (COMBAT), we attempt, for the first time, to quantify regional and global emissions of ammonia using a Bayesian inversion framework. For this reason, we will first develop a chemical scheme to account for the loss of ammonia through atmospheric reactions in the Lagrangian model FLEXPART. The model will then run backward in time for the calculation of the source-receptor relationships (SRRs). The SRRs along with ground-based measurements from the European Monitoring and Evaluation Programme (EMEP) and from the National Atmospheric Deposition Program (NADP) will be used in the inversion algorithm for the calculation of ammonia emissions. For the areas, where ground-based observations are lacking, satellite measurements will be used from the Atmospheric Infrared Sounder (AIRS) instrument of NASA's (National Aeronautics and Space Administration) Aqua satellite. The resulting optimised fluxes will be used to identify hot-spot emission areas and to verify bottom-up emission datasets, independently. In addition, a Eulerian model that includes full chemistry will be employed, in order to study potential effects on the population and the environment from the secondary particle formation. This will give scientists a better chance to quantify the environmental risk of the use of ammonia in agriculture.

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Funding scheme:

ROMFORSK-Program for romforskning