UK Ammonia Emissions Estimated With Satellite Observations and GEOS‐Chem

Abstract

 Satellite observations of NH3 from 2 sensors (IASI, CrIS) are used to estimate UK NH3 emissions in Mar-Sep at fine scales (10 km, monthly)  Satellite-derived NH3 emissions total 272 Gg from IASI and 389 Gg from CrIS and exhibit a spring (April) and summer (July) peak  Bottom-up emissions used for research and policy are 27-49% less than the satellitederived estimates and miss the summer emissions peak Accepted ArticleThis article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

4D‐Var Inversion of European NH3 Emissions Using CrIS NH3 Measurements and GEOS‐Chem Adjoint With Bi‐Directional and Uni‐Directional Flux Schemes

“…The large difference between our CrIS-derived estimates and the CrIS-based estimate from Marais et al ( 2021) is most likely caused by the different methods to calculate the top-down emissions: we used a Bayesian inversion in which the prior information imposes a penalty term on the emission optimization, whereas Marais et al (2021) directly rescale emissions using the column ratio between CrIS NH 3 and GC NH 3 . And the fact that the top-down annual emissions in Marais et al (2021) was scaled from satellite-derived monthly emissions from March to September using uncertain seasonal scaling factors might also contribute to the difference with our CrIS-derived emission estimates.…”

“…In terms of spatial coverage and long-term trends, satellite observations of NH 3 offer distinct advantages over surface NH x observations. Space-based observations of NH 3 have thus been leveraged to study and constrain the spatiotemporal variation and magnitude of NH 3 emissions and model simulations of NH x during the past decade (Cao et al, 2020;Chen et al, 2021;Clarisse, Van Damme, Gardner, et al, 2019;Dammers et al, 2019;Evangeliou et al, 2021;Marais et al, 2021;Schiferl et al, 2016;Van Damme et al, 2020;Van Damme et al, 2018;R. Wang et al, 2021;Warner et al, 2016Warner et al, , 2017L.…”

Satellite Data Applications for Site-Specific Air Quality Regulation in the UK: Pilot Study and Prospects

“…Few studies have focused on UK industrial point sources, and typically only large power stations such as Drax, the UK's largest NO 2 point source, are identified [38]. The majority of UK studies focus on combined source emissions over a large area, such as from large cities [22,25], or they investigate regional/national-scale changes [23,26]. In other countries with more favourable conditions, point source analysis has matured over the last 10 years.…”

“…Studies for government, such as the "Innovative technology to improve AQ monitoring" report for the Department for Environment, Food, and Rural Affairs (Defra) [18], the Highways England's "Strategy to improve air quality" [19] and the Scottish Government's "Clean air for Scotland strategy" [20], have identified satellite data products as a technology worthy of further investigation or implementation [21]. Defra are funding a project titled "Applying Earth Observation (EO) to Reduce Uncertainties in Emission Inventories", which has produced outputs demonstrating the potential of current satellites to validate UK National Atmospheric Emission Inventory (NAEI) for NO 2 and NH 3 [22,23]. The Scottish ClimateXchange Centre of expertise conducted a study, on behalf of the Scottish government, where satellite data was used to investigate urban and regional Scottish emission changes over time [24].…”

“…Certain regions, such as East Asia, the Middle East and the USA, feature heavily in satellite air quality studies, but difficulties with retrievals over the UK (see Section 3.1) mean it is often neglected, and UK sources are generally omitted from larger studies. Of the handful of UK studies in the literature, the majority focus on regional or city scale emission trends over time [23,[25][26][27][28][29]. This is not sufficient for air quality regulation, because emissions need to be attributable to individual sites/sources to inform the assessment of compliance.…”