Smarter analysis of satellite data for air quality regulators

Poor air quality is a clear threat to public and environmental health, but monitoring air quality is challenging, and regulators currently rely on sparse surface monitors, modelling, and activity-based scaling. Satellites offer a new but currently underutilised source of complementary data, where issues around complexity, applicability, and resources have restricted their use beyond research. This thesis explored the barriers and pathways to increasing the use of satellite data by air quality practitioners. Firstly, a Delphi study was conducted which found a strong appetite for collaboration across scientific and regulatory communities, identified key challenges that must be addressed to facilitate the transition from science to application, and called for a dedicated knowledge exchange framework to support this co-exploration of data.

Following the Delphi study, a range of satellite processing techniques were explored to increase the understanding and accessibility of this data. Methods were developed to isolate NO2 emission plumes and were applied to previously unobserved UK facilities. Building upon these methods, the influence of the Coriolis force on satellite emission estimates was identified and accounted for (∼9%). To increase the accessibility of satellite data, a user-friendly tool was developed to isolate and quantify satellite-observed plumes, which successfully identified NO2 plumes from individual facilities on daily timescales, even in polluted regions, and emission rates compared well (±35%) to reported values.

Finally, a collection of policy-relevant case studies showcased the capabilities of current satellites, which identified long-term negative trends in NO2 following transport and energy legislation, concerning growth in county-level NH3 including peak season changes, and reductions in NO2 following COVID-19 lockdowns.

This thesis laid out the initial framework, both in terms of knowledge exchange and technical development, for the uptake of satellite data by UK regulators. Whilst considerable work remains to unlock the value of satellite intelligence, its potential cannot be ignored.