NH<sub>3</sub> emissions from large point sources derived from CrIS and IASI satellite observations

Abstract

Abstract. Ammonia (NH3) is an essential reactive nitrogen species in the biosphere and through its use in agriculture in the form of fertilizer (important for sustaining humankind). The current emission levels, however, are up to 4 times higher than in the previous century and continue to grow with uncertain consequences to human health and the environment. While NH3 at its current levels is a hazard to environmental and human health, the atmospheric budget is still highly uncertain, which is a product of an overall lack of measurements. The capability to measure NH3 with satellites has opened up new ways to study the atmospheric NH3 budget. In this study, we present the first estimates of NH3 emissions, lifetimes and plume widths from large (>∼5 kt yr−1) agricultural and industrial point sources from Cross-track Infrared Sounder (CrIS) satellite observations across the globe with a consistent methodology. The same methodology is also applied to the Infrared Atmospheric Sounding Interferometer (IASI) (A and B) satellite observations, and we show that the satellites typically provide comparable results that are within the uncertainty of the estimates. The computed NH3 lifetime for large point sources is on average 2.35±1.16 h. For the 249 sources with emission levels detectable by the CrIS satellite, there are currently 55 locations missing (or underestimated by more than an order of magnitude) from the current Hemispheric Transport Atmospheric Pollution version 2 (HTAPv2) emission inventory and only 72 locations with emissions within a factor of 2 compared to the inventories. The CrIS emission estimates give a total of 5622 kt yr−1, for the sources analyzed in this study, which is around a factor of ∼2.5 higher than the emissions reported in HTAPv2. Furthermore, the study shows that it is possible to accurately detect short- and long-term changes in emissions, demonstrating the possibility of using satellite-observed NH3 to constrain emission inventories.

Ammonia measurements from space with the Cross-track Infrared Sounder: characteristics and applications

“…Similarly, the diurnal emission profile can be approximated by using the diurnal emission profile for livestock that is used to prepare emissions for the GEM-MACH model. Most of the emissions around Lethbridge are from livestock, which has a peak in the morning to middle of the day following cattle activity including feeding and excretion and the in-creasing surface temperatures (Denmead et al, 2014;Van Haarlem et al, 2008), and are thus emitted before the satellite overpass time (∼ 01:30 LT). Thus, the inventory value from an hour before the overpass (12:30 LT) is used to adjust the emissions to daily averages by a factor of 1/1.44 leading to a final annual emission total of 37.1 ± 6.3 kt yr −1 .…”

The 2018 fire season in North America as seen by TROPOMI: aerosol layer height intercomparisons and evaluation of model-derived plume heights

“…Due to the nature of wildfires with plume heights reaching several kilometres, aerosol plumes produced by wildfires can be transported over vast distances (e.g. Damoah et al, 2004;Derwent et al, 2004;Duck et al, 2007;Lutsch et al, 2016Lutsch et al, , 2019. Plumes from larger fires can thus cause aviation hazards and affect regional air quality thousands of kilometres away from the source and even across continents (e.g.…”

Multiscale observations of NH3 around Toronto, Canada

“…Atmospheric NH 3 is rapidly removed by wet and dry deposition as well as by reactions with acids in the atmosphere, and thus has a relatively short lifetime ranging from a few hours to a few days (Galloway et al, 2003;Dammers et al, 2019). NH 3 lifetime may be longer for certain cases, such as biomass burning emissions that inject NH 3 into the free troposphere, attenuating depositional and chemical losses, although physical and chemical mechanisms that lead to transport of NH 3 in biomass burning plumes over long distances remain uncertain (Lutsch et al, 2016(Lutsch et al, , 2019b.…”

“…A study by Hu et al (2014) investigating NH 3 in downtown Toronto has shown that greenery within the city is an important source of NH 3 when temperatures are above freezing, and that potential sources at temperatures below freezing have yet to be investigated. Additionally, recent studies have shown the increased capacity for satellite-based instruments to measure spatial and temporal distributions of NH 3 total columns at global Warner et al, 2016;Shephard et al, 2020), regional Warner et al, 2017;Viatte et al, 2020), and point-source scales (Van Damme et al, 2018;Clarisse et al, 2019a;Dammers et al, 2019).…”