Publikasjoner

Uncertainties in assessing the environmental impact of amine emissions from a CO2 capture plant.

Karl, M.; Castell, N.; Simpson, D.; Solberg, S.; Starrfelt, J.; Svendby, T.; Walker, S.-E.; Wright, R.F.

Uncertainties in monitoring of SVOCs in air caused by within-sampler degradation during active and passive air sampling.

Melymuk, L.; Bohlin-Nizzetto, P.; Prokeš, R.; Kukucka, P.; Pribylová, P.; Vojta, Š.; Kohoutek, J.; Lammel, G.; Klánová, J.

Uncertainties in recent satellite ozone profile trend assessments (SI2N, WMO 2014) : A network-based assessment of fourteen contributing limb and occultation data records.

Hubert, D.; Lambert, J.-C.; Verhoelst, T.; Granville, J.; Keppens, A.; Cortesi, U.; Degenstein, D.,A.; Froidevaux, L.; Godin-Beekmann, S.; Hoppel, K.,W.; Kyrölä, E.; Leblanc, T.; Lichtenberg, G.; McDermid, S.; McElroy, T.; Murtagh, D.; Nakane, H.; Russell III, J.R.; Smit, H.G.J.; Stebel, K.; Steinbrecht, W.; Stübi, R.; Swart, D.P.J.; Taha, G.; Thompson, A.M.; Urban, J.; van Gijsel, A.; von der Gathen, P.; Walker, K.A.; Zawodny, J.M.

Uncertainties in the inverse modelling of sulphur dioxide eruption profiles. Corrigendum.

Seibert, P.; Kristiansen, N.I.; Richter, A.; Eckhardt, S.; Prata, A.J.; Stohl, A.

Uncertaintines in the inverse modelling of sulphur dioxide eruption profiles.

Seibert, P.; Eckhardt, S.; Kristiansen, N.; Prata, F.; Richter, A.; Stohl, A.

Uncertainty analysis of modelling studies included in air quality assessments.

Moussiopoulos, N.; Sahm, P.; Munchow, S.; Tønnesen, D.; de Leeuw, F.; Tarrasón, L.

Uncertainty assessment and applicability of an inversion method for volcanic ash forecasting.

Steensen, B. M.; Kylling, A.; Kristiansen, N. I.; Schulz, M.

Uncertainty assessment in European air quality mapping and exposure studies. NILU F

Denby, B.R.; Horalek, J.; de Leeuw, F.; de Smet, P.

Uncertainty in Citizen Science observations: from measurement to user perception.

Lahoz, W.; Schneider, P.; Castell, N.

Uncertainty in mapping urban air quality using crowdsourcing techniques.

Schneider, P.; Castell, N.; Lahoz, W.; Bartonova, A.; the CITI-SENSE Consortium Team.

Uncertainty mapping for air quality modelling and data assimilation. Powerpoint presentation. NILU F

Denby, B.; Costa, A.M.; Monteiro, A.; Dudek, A.; Walker, S.E.; van den Elshout, S.; Fisher, B.

Unchanged PM2.5 levels over Europe during COVID-19 were buffered by ammonia

Evangeliou, Nikolaos; Tichý, Ondřej; Otervik, Marit Svendby; Eckhardt, Sabine; Balkanski, Yves; Hauglustaine, Didier A.

The coronavirus outbreak in 2020 had a devastating impact on human life, albeit a positive effect on the environment, reducing emissions of primary aerosols and trace gases and improving air quality. In this paper, we present inverse modelling estimates of ammonia emissions during the European lockdowns of 2020 based on satellite observations. Ammonia has a strong seasonal cycle and mainly originates from agriculture. We further show how changes in ammonia levels over Europe, in conjunction with decreases in traffic-related atmospheric constituents, modulated PM2.5. The key result of this study is a −9.8 % decrease in ammonia emissions in the period of 15 March–30 April 2020 (lockdown period) compared to the same period in 2016–2019, attributed to restrictions related to the global pandemic. We further calculate the delay in the evolution of the ammonia emissions in 2020 before, during, and after lockdowns, using a sophisticated comparison of the evolution of ammonia emissions during the same time periods for the reference years (2016–2019). Our analysis demonstrates a clear delay in the evolution of ammonia emissions of −77 kt, which was mainly observed in the countries that imposed the strictest travel, social, and working measures. Despite the general drop in emissions during the first half of 2020 and the delay in the evolution of the emissions during the lockdown period, satellite and ground-based observations showed that the European levels of ammonia increased. On one hand, this was due to the reductions in SO2 and NOx (precursors of the atmospheric acids with which ammonia reacts) that caused less binding and thus less chemical removal of ammonia (smaller loss – higher lifetime). On the other hand, the majority of the emissions persisted because ammonia mainly originates from agriculture, a primary production sector that was influenced very little by the lockdown restrictions. Despite the projected drop in various atmospheric aerosols and trace gases, PM2.5 levels stayed unchanged or even increased in Europe due to a number of reasons that were attributed to the complicated system. Higher water vapour during the European lockdowns favoured more sulfate production from SO2 and OH (gas phase) or O3 (aqueous phase). Ammonia first reacted with sulfuric acid, also producing sulfate. Then, the continuously accumulating free ammonia reacted with nitric acid, shifting the equilibrium reaction towards particulate nitrate. In high-free-ammonia atmospheric conditions such as those in Europe during the 2020 lockdowns, a small reduction in NOx levels drives faster oxidation toward nitrate and slower deposition of total inorganic nitrate, causing high secondary PM2.5 levels.