Satellite evidence for changes in the NO2 weekly cycle over large cities
Stavrakou, T., Müller, J., Bauwens, M.,
Boersma, K.F. and van Geffen, J.: 2020,
Sci. Rep. 10, 10066, 9 pp.
Abstract
Anthropogenic activities, by far the largest source of NOx into the
atmosphere, induce a weekly cycle of NO2 abundances in cities. Comprehensive
analysis of the 2005-2017 OMI NO2 dataset reveals significant weekly
cycles in 115 of the 274 cities considered. These results are corroborated
by a full year of high-resolution TROPOMI NO2 observations. The OMI dataset
permits us to identify trends in the weekly cycle resulting from NOx
emissions changes. The data show a clear weakening of the weekly cycle over
European and U.S. cities, an evolution attributed to the decline in
anthropogenic emissions and the resulting growing importance of background
NO2, whereas NO2 lifetime changes also play a minor role. In particular, the
Sunday NO2 columns averaged over all U.S. cities are found to increase,
relative to the weekly average, from 0.72 during 2005-2007 to 0.88 in
2015-2017. The opposite tendency is recorded in regions undergoing rapid
emission growth. Multiyear simulations over the U.S. and the Middle East
using the chemistry-transport model MAGRITTEv1.1 succeed in capturing the
observed weekly cycles over the largest cities, as well as the observed
long-term trends in the weekly cycle.
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created: 22 June 2020
last modified: 19 August 2020