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1. Conditional extraction of air-pollutant source signals from air-quality monitoring.

Author

Malby, Andrew R., Whyatt, J. Duncan, and Timmis, Roger J.

Subjects
*AIR pollutants, *AIR quality, *EMISSIONS (Air pollution), *METEOROLOGY, *CLIMATE change, *TRAFFIC flow, *ENVIRONMENTAL impact analysis
Abstract

Abstract: Ambient air-quality data contain information about air-pollution sources that is currently under-exploited. This information could be used to assess trends in the emissions performance of specific sources, and to check at an early stage if policies or controls to reduce air-quality impacts from particular sources are working. Previous techniques for extracting such information have tended to adopt complex analyses and to rely on data from monitoring networks with many sites, thus limiting their applicability to non-specialist users and to networks with few sites. This paper describes simple techniques for ‘conditionally’ selecting data from one or two monitors, and for analysing and interpreting concentrations in terms of source performance or policy progress. Our techniques minimise the effects of variations in meteorology and source activity, so that the selected data give a more consistent indication of individual source performance. We demonstrate our techniques with a case study, in which we track the source performance of road traffic on the M4 motorway in London and show how impacts per vehicle have changed over time under different conditions of traffic flow and fleet composition. [Copyright &y& Elsevier]

Published
2013
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2. Early spring near-surface ozone in Europe during the COVID-19 shutdown: Meteorological effects outweigh emission changes

Author

Ricardo García-Herrera, Jose M. Garrido-Perez, Carlos Ordóñez, Ministerio de Economía y Competitividad (España), Ministerio de Educación, Cultura y Deporte (España), Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), European Commission, Ordóñez, C., and Ordóñez, C. [0000-0003-2990-0195]

Subjects
Pollution, Mediterranean climate, Environmental Engineering, Ozone, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Pneumonia, Viral, Air pollution, Climate change, 010501 environmental sciences, medicine.disease_cause, Atmospheric sciences, NO2, 01 natural sciences, Article, chemistry.chemical_compound, Betacoronavirus, Meteorology, Air Pollution, medicine, Environmental Chemistry, Humans, Nitrogen dioxide, Waste Management and Disposal, Air quality index, Pandemics, 0105 earth and related environmental sciences, media_common, Air Pollutants, SARS-CoV-2, Física atmosférica, Humidity, COVID-19, Coronavirus, Europe, chemistry, Air quality, Environmental science, Seasons, Coronavirus Infections, Environmental Monitoring
Abstract

This paper analyses the impact of the control measures during the COVID-19 lockdown in Europe (15 March–30 April 2020) on 1-h daily maximum nitrogen dioxide (NO2) and maximum daily 8-h running average ozone (MDA8 O3) observations obtained from the European Environment Agency's air quality database (AirBase). Daily maximum NO2 decreased consistently over the whole continent, with relative reductions ranging from 5% to 55% with respect to the same period in 2015–2019 for 80% of the sites considered (10th – 90th percentiles). However, MDA8 O3 concentrations showed a different pattern, decreasing over Iberia and increasing elsewhere. In particular, a large region from northwestern to central Europe experienced increases of 10–22% at urban background stations, reaching typical values of the summer season. The analysis of the expected NO2 and O3 concentrations in the absence of the lockdown, using generalised additive models fed by reanalysis meteorological data, shows that the low NO2 concentrations were mostly attributed to the emission reductions while O3 anomalies were dominated by the meteorology. The relevance of each meteorological variable depends on the location. The positive O3 anomalies in northwestern and central Europe were mostly associated with elevated temperatures, low specific humidity and enhanced solar radiation. This pattern could be an analogue to study the limits of pollution control policies under climate change scenarios. On the other hand, the O3 reduction in Iberia is mostly attributable to the low solar radiation and high specific humidity, although the reduced zonal wind also played a role in the proximity of the Iberian Mediterranean coast., This work was supported by the Spanish Ministerio de Economía y Competitividad [grant number RYC-2014-15036] and the Spanish Ministerio de Educación, Cultura y Deporte [grant number FPU16/01972]. We also acknowledge support from STEADY (CGL2017-83198-R), project funded by the Spanish Ministerio de Economía, Industria y Competitividad. The authors are grateful to the European Environment Agency for making NO2 and O3 data available through the Air-Base air quality database as well as to NOAA/OAR/ESRL PSD for providing NCEP reanalysis data. The authors thank the anonymous reviewers and editors for their constructive and useful comments.

Published
2020