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Abrupt recent trend changes in atmospheric nitrogen dioxide over the Middle East.

Lelieveld J, Beirle S, Hörmann C, Stenchikov G, Wagner T - Sci Adv (2015)

Bottom Line: Strong upward NO2 trends have been observed over South and East Asia and the Middle East, in particular over major cities.We show, however, that a combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East.Large changes, including trend reversals, have occurred since about 2010 that could not have been predicted and therefore are at odds with emission scenarios used in projections of air pollution and climate change in the early 21st century.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Chemistry, 55128 Mainz, Germany. ; The Cyprus Institute, 1645 Nicosia, Cyprus. ; King Saud University, Riyadh 11451, Saudi Arabia.

ABSTRACT
Nitrogen oxides, released from fossil fuel use and other combustion processes, affect air quality and climate. From the mid-1990s onward, nitrogen dioxide (NO2) has been monitored from space, and since 2004 with relatively high spatial resolution by the Ozone Monitoring Instrument. Strong upward NO2 trends have been observed over South and East Asia and the Middle East, in particular over major cities. We show, however, that a combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East. Large changes, including trend reversals, have occurred since about 2010 that could not have been predicted and therefore are at odds with emission scenarios used in projections of air pollution and climate change in the early 21st century.

No MeSH data available.


Related in: MedlinePlus

NO2 column densities over 16 cities in the Middle East.Annual mean NO2 during 2005–2014, indicating NOx emission trend changes around 2010. Vertical bars represent the SEM.
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Figure 2: NO2 column densities over 16 cities in the Middle East.Annual mean NO2 during 2005–2014, indicating NOx emission trend changes around 2010. Vertical bars represent the SEM.

Mentions: Over Greece and particularly in Athens, however, an overall negative trend of about −4%/year between 1996 and 2011 has been observed (18), which accelerated to −10%/year between 2008 and 2012 (12). In Fig. 2, we show the evolution of annual mean NO2 column densities over Athens and 15 additional cities in the region between 2005 and 2014, averaging over areas of 100 × 100 km2, hence including the city surroundings. Figure S1 shows similar results over smaller areas of 30 × 30 km2, focusing more on the central parts of these cities. Both figures demonstrate that the trends and interannual variability are much larger than the standard error of the mean (SEM), indicating that they are significant, most distinct for the 100 × 100 km2 footprint in Fig. 2. The NO2 decline over Athens of about 40% since 2008 corroborates previous estimates. The latter likewise applies to the other cities mentioned above, that is, for the period up to 2010, for which strong upward trends have been reported. Figure 2 also reveals that since 2010, trend reversals have occurred over these particular cities. Because the atmospheric lifetime of NOx is less than a day in urban plumes, typically several hours in the Middle East, NO2 over cities is closely related to local NOx emissions (27).


Abrupt recent trend changes in atmospheric nitrogen dioxide over the Middle East.

Lelieveld J, Beirle S, Hörmann C, Stenchikov G, Wagner T - Sci Adv (2015)

NO2 column densities over 16 cities in the Middle East.Annual mean NO2 during 2005–2014, indicating NOx emission trend changes around 2010. Vertical bars represent the SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643803&req=5

Figure 2: NO2 column densities over 16 cities in the Middle East.Annual mean NO2 during 2005–2014, indicating NOx emission trend changes around 2010. Vertical bars represent the SEM.
Mentions: Over Greece and particularly in Athens, however, an overall negative trend of about −4%/year between 1996 and 2011 has been observed (18), which accelerated to −10%/year between 2008 and 2012 (12). In Fig. 2, we show the evolution of annual mean NO2 column densities over Athens and 15 additional cities in the region between 2005 and 2014, averaging over areas of 100 × 100 km2, hence including the city surroundings. Figure S1 shows similar results over smaller areas of 30 × 30 km2, focusing more on the central parts of these cities. Both figures demonstrate that the trends and interannual variability are much larger than the standard error of the mean (SEM), indicating that they are significant, most distinct for the 100 × 100 km2 footprint in Fig. 2. The NO2 decline over Athens of about 40% since 2008 corroborates previous estimates. The latter likewise applies to the other cities mentioned above, that is, for the period up to 2010, for which strong upward trends have been reported. Figure 2 also reveals that since 2010, trend reversals have occurred over these particular cities. Because the atmospheric lifetime of NOx is less than a day in urban plumes, typically several hours in the Middle East, NO2 over cities is closely related to local NOx emissions (27).

Bottom Line: Strong upward NO2 trends have been observed over South and East Asia and the Middle East, in particular over major cities.We show, however, that a combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East.Large changes, including trend reversals, have occurred since about 2010 that could not have been predicted and therefore are at odds with emission scenarios used in projections of air pollution and climate change in the early 21st century.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Chemistry, 55128 Mainz, Germany. ; The Cyprus Institute, 1645 Nicosia, Cyprus. ; King Saud University, Riyadh 11451, Saudi Arabia.

ABSTRACT
Nitrogen oxides, released from fossil fuel use and other combustion processes, affect air quality and climate. From the mid-1990s onward, nitrogen dioxide (NO2) has been monitored from space, and since 2004 with relatively high spatial resolution by the Ozone Monitoring Instrument. Strong upward NO2 trends have been observed over South and East Asia and the Middle East, in particular over major cities. We show, however, that a combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East. Large changes, including trend reversals, have occurred since about 2010 that could not have been predicted and therefore are at odds with emission scenarios used in projections of air pollution and climate change in the early 21st century.

No MeSH data available.


Related in: MedlinePlus