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High Resolution Satellite Data Assessment of Air Quality Interventions

Background: The Automatic Urban and Rural Network (AURN) is a network of over 300 terrestrial air quality monitoring stations in the UK managed by the Department for Environment, Food and Rural Affairs (Defra)[1]. It was set up to demonstrate compliance with regulatory air quality standards, but its public archives have also been used to inform a wide range of air pollution source apportionment, impact assessment and pollution abatement activities across the UK[2]. In more recent years, satellite systems, e.g. the European Space Agency (ESA) TROPOMI instrument on‐board Sentinel‐5 Precursor (S5P)[3], have begun to provide high-resolution air quality measurements that can complement such ground-based air quality monitoring data. Research is on-going exploring the overlap between these two data-types[4]. However, it is arguably not until COVID-19, or more specifically the investigation of the air quality impact of associated lockdown activities, that many of the potential extra insights that satellite data could provide were widely acknowledged[5].

Project Remit: Looking forward, as we (hopefully) begin to move out of lockdown, many of the air quality issues we face are likely to be smaller-scale and more localised. Major cities across the UK, e.g. Leeds, Birmingham and Southampton, were in the process of implementing Clean Air Zone (CAZ) measures[6], and evidence is needed to inform local and national authorities in their efforts to implement and evaluate the performance of these interventions. Discrete change detection methods like break-points have previously been applied to air quality data to study air pollution concentration changes associated with interventions[e.g. 7]. However, within this project we will use recent refinements that we have developed to these methods, fitting gradients to periods of likely change to better handle non-instantaneous change[8], to provide unique insights into the magnitude and geographical scale of the impact of contemporary air quality interventions like the CZAs. A series of recent events, already characterised using terrestrial air quality data, will first be used as case studies for the development and testing phases of this research using traditional and our new methods. Likely case studies will be those that are clearly identified in TROPOMI NO2 measurements and in AURN data, so most obviously the COVID-19 related lockdown[5] but recent Low Emission Zones and large-scale vehicle fleet upgrades including retrofit and upgrade programmes[e.g. 9,10], would also be investigated. Similar earlier events, e.g. the closure of UK airports following the 2010 eruption of Icelandic volcano Eyjafjallajökull[e.g. 11], may also be of interest but, being prior to the launch of TROPOMI, could only be studied at the lower resolution of earlier satellite systems.

Studentship: Based at the University of Leeds under the supervision of Dr Karl Ropkins (Leeds, Environment/Transport Studies,, Dr Richard Pope (Leeds, Environment/Earth Observation), and Professor Ruth Doherty (Edinburgh, Geosciences/Atmospheric sciences).

REFERENCES: [1]; [2] Carslaw, D.C. and Ropkins, K., 2012. Openair—an R package for air quality data analysis. Environmental Modelling & Software, 27, pp.52-61.; [3] Veefkind, J.P., Aben, I., McMullan, K., Förster, H., De Vries, J., Otter, G., Claas, J., Eskes, H.J., De Haan, J.F., Kleipool, Q. and Van Weele, M., 2012. TROPOMI on the ESA Sentinel-5 Precursor: A GMES mission for global observations of the atmospheric composition for climate, air quality and ozone layer applications. Remote Sensing of Environment, 120, pp.70-83.; [4] Pope, R.J., Graham, A.M., Chipperfield, M.P. and Veefkind, J.P., 2019. High resolution satellite observations give new view of UK air quality. Weather, 74(9), pp.316-320.; [5]; [6]; [7] Carslaw, D.C. and Carslaw, N., 2007. Detecting and characterising small changes in urban nitrogen dioxide concentrations. Atmospheric Environment, 41(22), pp.4723-4733.; [8] Ropkins, K., Tate, J.E., Walker, A., Clark, T., in preparation, Measuring the Impact of Air Quality Related Interventions; [9] Bigazzi, A.Y. and Rouleau, M., 2017. Can traffic management strategies improve urban air quality? A review of the evidence. Journal of Transport & Health, 7, pp.111-124.; [10] Austin, W., 2019. School Bus Diesel Retrofits, Air Quality, and Academic Performance: National Evidence Using Satellite Data.; [11] Colette, A., Favez, O., Meleux, F., Chiappini, L., Haeffelin, M., Morille, Y., Malherbe, L., Papin, A., Bessagnet, B., Menut, L. and Leoz, E., 2011. Assessing in near real time the impact of the April 2010 Eyjafjallajökull ash plume on air quality. Atmospheric Environment, 45(5), pp.1217-1221.