Reductions in nitrogen oxides over Europe driven by environmental policy and economic recession

Abstract

Fuel combustion is a significant source of numerous air pollutants, which reduce local air quality, and affect global tropospheric chemistry. Satellite observations of nitrogen dioxide, emitted by combustion processes, allow for robust monitoring of atmospheric concentrations at high spatial resolution on continental scales. Here we evaluate changes in tropospheric NO2 concentrations over Europe between 2004 and 2010. We isolate long-term (timescales greater than one year) variability in the daily NO2 observations from the Ozone Monitoring Instrument (OMI) using a spectral analysis. In 2010, we find substantial reductions in NO2 concentrations of at least 20% throughout Europe. These reductions are as much the result of temporary reductions prompted by the 2008–2009 global economic recession, as of European NOx emission controls. Our results demonstrate that realistic concentration pathways of NO2 do not follow simple linear trends, but reflect a compilation of environmental policy and economic activity.

The version 3 OMI NO<sub>2</sub> standard product

“…cm −2 ) over less polluted regions. During the OMI mission we see significant NO 2 reductions with time (∼ 25 % for RandstadRuhr and ∼ 40 % for the Po River valley) related to national regulations and EU air quality directives aimed at reducing emissions from transportation and power sectors and creating a sustainable living environment Castellanos and Boersma, 2012). As seen in the I-95 and Ohio Valley samples, SPv2 and SPv3 retrieved tropospheric columns give trends that are well within statistical uncertainties of each other for both European regions (Fig.…”

“…Satellite NO 2 data have been used as a proxy for (1) NO x emissions (van der A et al, 2017;Beirle et al, 2011;Boersma et al, 2015;Castellanos and Boersma, 2012;Curier et al, 2014;Ding et al, 2015;Duncan et al, 2014, de Foy et al, 2014Ghude et al, 2013;Jaeglé et al, 2004;Konovalov et al, 2006Konovalov et al, , 2010Lamsal et al, 2011;Liu et al, 2016;Lu et al, 2015;Lu and Streets, 2012;Martin et al, 2006;McLinden et al, 2016;Mijling and Van Der A, 2012;Richter et al, 2004Richter et al, , 2005Russell et al, 2012;Stavrakou et al, 2008;Streets et al, 2013;Vinken et al, 2014;Zhang et al, 2007;Zhou et al, 2012); (2) groundlevel NO 2 (Lamsal et al, 2008) and NO 2 deposition (Nowlan et al, 2014); and (3) emissions of co-emitted gases, including other pollutants, like particulate matter, and greenhouse gases, such as CO 2 (Berezin et al, 2013;Konovalov et al, 2016;Reuter et al, 2014).…”

Decadal record of satellite carbon monoxide observations

“…The observed minimum in CO in early 2009 overlaps with the recorded dip in manufacturing (Alcorta and Nixson, 2011) along with related transportation and shipping decreases (de Ruyter de Wildt et al, 2012). Declines due to the economic crisis are clearly observed for NO 2 in Europe (Castellanos and Boersma, 2012) and the US (Russell et al, 2012), however, given the longer lifetime of CO, this would require further study (inverse modeling) for attribution.…”

Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide

“…Satellite observations on the other hand offer a unique opportunity for studying the continuous spatial patterns and the temporal dynamics of the constituents affecting air quality in general (Martin, 2008;Burrows et al, 2011;Lahoz et al, 2012;Duncan et al, 2014) and of tropospheric NO 2 in particular Martin, 2008;Zhou et al, 2012;Castellanos and Boersma, 2012;Schneider and van der A, 2012;Hilboll et al, 2013;Curier et al, 2014).…”