Time-resolved emission reductions for atmospheric chemistry modelling in Europe during the COVID-19 lockdowns

Abstract

Abstract. We quantify the reductions in primary emissions due to the COVID-19 lockdowns in Europe. Our estimates are provided in the form of a dataset of reduction factors varying per country and day that will allow modelling and identifying the associated impacts upon air quality. The country- and daily-resolved reduction factors are provided for each of the following source categories: energy industry (power plants), manufacturing industry, road traffic and aviation (landing and take-off cycle). We computed the reduction factors based on open access and near-real time measured activity data from a wide range of information sources. We also trained a machine learning model with meteorological data to derive weather-normalised electricity consumption reductions. The time period covered is from 21 February, when the first European localised lockdown was implemented in the region of Lombardy (Italy), until 26 April 2020. This period includes five weeks (23 March until 26 April) with the most severe and relatively unchanged restrictions upon mobility and socio-economic activities across Europe. The computed reduction factors were combined with the Copernicus Atmosphere Monitoring Service's European emission inventory using adjusted emission temporal profiles in order to derive time-resolved emission reductions per country and pollutant sector. During the most severe lockdown period, we estimate the average emission reductions to be −33 % for NOx, −8 % for NMVOC, −7 % for SOx and −7 % for PM2.5 at the EU-30 level (EU-28 plus Norway and Switzerland). For all pollutants more than 85 % of the total reduction is attributable to road transport, except SOx. The reductions reached −50 % (NOx), −14 % (NMVOC), −12 % (SOx) and −15 % (PM2.5) in countries where the lockdown restrictions were more severe such as Italy, France or Spain. To show the potential for air quality modelling we simulated and evaluated NO2 concentration decreases in rural and urban background regions across Europe (Italy, Spain, France, Germany, United-Kingdom and Sweden). We found the lockdown measures to be responsible for NO2 reductions of up to −58 % at urban background locations (Madrid, Spain) and −44 % at rural background areas (France), with an average contribution of the traffic sector to total reductions of 86 % and 93 %, respectively. A clear improvement of the modelled results was found when considering the emission reduction factors, especially in Madrid, Paris and London where the bias is reduced with more than 90 %. Future updates will include the extension of the COVID-19 lockdown period covered, the addition of other pollutant sectors potentially affected by the restrictions (commercial/residential combustion and shipping) and the evaluation of other air quality pollutants such as O3 and PM2.5. All the emission reduction factors are provided in the supplementary material.

COVID‐19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere

“…However, the chemical regime for ozone in the free troposphere is different (e.g., Kroll et al., 2020; Sillman, 1999; Thornton et al., 2002), and free tropospheric ozone reductions are expected after the substantial decrease of precursor emissions due to the COVID‐19 pandemic (e.g. Guevara et al., 2020; Zhang et al., 2020).…”

“…Guevara et al. (2020), or Barré et al. (2020) report European emissions reductions up to 60% for NO x , and up to 15% for Non‐Methane Volatile Organic Compounds (NMVOC) in March/April 2020.…”

“…Widespread measures to contain the COVID-19 pandemic have slowed, or even closed down, industries, businesses, and transportation activities, and have reduced anthropogenic emissions substantially throughout the year 2020. Guevara et al (2020), or Barré et al (2020) report European emissions reductions up to 60% for NO x , and up to 15% for Non-Methane Volatile Organic Compounds (NMVOC) in March/April 2020. Based on satellite observations of NO 2 columns (Bouwens et al, 2020), comparable NO x emissions reductions are reported for Chinese cities in February 2020 (Ding et al, 2020;Feng et al, 2020).…”

Estimating lockdown induced European NO<sub>2</sub> changes

“…The spatial resolution of the emissions is 0.1°x0.05° but later re-gridded at 0.1°x0.1° to match the models' grid. The alternative emission scenario, corresponding to the lockdown period, was derived by combining the original CAMS-REG-AP inventory with a set of country-and sector-resolved reduction factors (Guevara et al, 2020). For the present work, time invariant emission reduction factors where proposed by country and for three activity sectors: manufacturing industry, road transport, and aviation (landing and take-off cycles) that are reduced on average by 15.5%, 54% and 94%, respectively.…”

“…In Europe, lockdown measures were implemented at various dates during February and March 2020. These lockdowns drastically reduced traffic and also activity levels in most industries (Guevara et al, 2020;Le Quéré et al, 2020). These sectors represent a large share of NOx emissions (51% according to EEA 2020a).…”