NO<sub><i>x</i></sub> emission estimates during the 2014 Youth Olympic Games in Nanjing
The Nanjing Government applied temporary environmental regulations to guarantee good air quality during the Youth Olympic Games (YOG) in 2014. We study the effect of those regulations by applying the emission estimate algorithm DECSO (Daily Emission estimates Constrained by Satellite Observations) t...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/15/9399/2015/acp-15-9399-2015.pdf |
| Summary: | The Nanjing Government applied temporary environmental regulations to
guarantee good air quality during the Youth Olympic Games (YOG) in 2014. We
study the effect of those regulations by applying the emission estimate
algorithm DECSO (Daily Emission estimates Constrained by Satellite
Observations) to measurements of the Ozone Monitoring Instrument (OMI). We
improved DECSO by updating the chemical transport model CHIMERE from v2006 to
v2013 and by adding an Observation minus Forecast (OmF) criterion to filter
outlying satellite retrievals due to high aerosol concentrations. The
comparison of model results with both ground and satellite observations
indicates that CHIMERE v2013 is better performing than CHIMERE v2006. After
filtering the satellite observations with high aerosol loads that were
leading to large OmF values, unrealistic jumps in the emission estimates are
removed. Despite the cloudy conditions during the YOG we could still see a
decrease of tropospheric NO<sub>2</sub> column concentrations of about 32 % in
the OMI observations when compared to the average NO<sub>2</sub> columns from 2005 to
2012. The results of the improved DECSO algorithm for NO<sub><i>x</i></sub> emissions show
a reduction of at least 25 % during the YOG period and afterwards. This
indicates that air quality regulations taken by the local government have an
effect in reducing NO<sub><i>x</i></sub> emissions. The algorithm is also able to detect
an emission reduction of 10 % during the Chinese Spring Festival. This
study demonstrates the capacity of the DECSO algorithm to capture the change
of NO<sub><i>x</i></sub> emissions on a monthly scale. We also show that the observed
NO<sub>2</sub> columns and the derived emissions show different patterns that
provide complimentary information. For example, the Nanjing smog episode in
December 2013 led to a strong increase in NO<sub>2</sub> concentrations without an
increase in NO<sub><i>x</i></sub> emissions. Furthermore, DECSO gives us important
information on the non-trivial seasonal relation between NO<sub><i>x</i></sub> emissions
and NO<sub>2</sub> concentrations on a local scale. |
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| ISSN: | 1680-7316 1680-7324 |