1. e-mail: wangting@mail.iap.ac.cn
The Evolution of NO2 over Beijing and its vicinity during an extended period of APEC 2014
Ting Wang1, François Hendrick2,
Pucai Wang1, Nan Hao3,
Jianzhong Ma4, Lin Zhang5,
Junli Jin4, Huan Yu2,
and Michel Van Roozendael2
(1) Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences, Beijing, China
(2) Belgian Institute for Space Aeronomy (IASB-BIRA), Brussels, Belgium
(3) Institut für Methodik der Fernerkundung (IMF), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany
(4) Chinese Academy of Meteorological Sciences, Beijing, China
(5) Peking University, , Beijing, China
Brussels，

2. Content (1) background (2) data
(3) variation of NO2 during an extended period of APEC 2014
(4) conclusion
(a). Ground-based MAX-DOAS and meteorological data
(b). Satellite (NASA OMI)
(c). Model (GEOS-Chem)

3. (1)background
The Asia-Pacific Economic Cooperation (APEC) Meeting was hosted on 5-11 November in Beijing.
(1)the Concluding Senior Ocials’ Meeting on 5–6 November;
(2) the 26th APEC Ministerial Meeting on 7–8 November;
(3) the APEC CEO Summit CEO Summit on 9–10 November
(4)and the 22nd APEC Economic Leaders’ Meeting on 10–11 November.

4. (1)background
Air quality controls are necessary in Beijing and its surrounding. ?

5. (1)background Emission control
Emission Control Period: Nov , 2014
Emission Control Region: Beijing and surrounding provinces
Emission Control Measures:
Beijing: 50% vehicles restriction (Nov )
closing construction sites (Nov )
stopping 40% coal-fired units
closing heavy polluted factories
a holiday for citizens to minimize the emission of
social activities(Nov. 7-12)
Surrounding Provinces:17 cities 50% vehicles restriction (Nov. 6-12)
closing construction sites
From Beijing Municipal Environmental Protection Bureau：

6. (2)data
The datasets below were used to quantitatively describe the effect of the emission control and weather condition on NO2 over Beijing and its vicinity during APEC period:
(a) Xianghe MAX-DOAS : Oct. ~ 30 Nov. , 2011—2014 .
Xianghe meteorological data: Oct. ~ 30 Nov. , 2011—2014 .
Satellite data (OMI): Oct. ~ 30 Nov. , 2011—2014 .
Beijing MAX-DOAS : Oct. ~ 30 Nov. , 2014.
Model result (geo-chem): Oct. ~ 30 Nov. ,
The wavelength band for retrieving NO2 is 425—490nm and 400 —420nm for Xianghe and Beijing’s MAX-DOAS respectively.
In the GEOS-Chem model settings , there is no change for the source emissions, in order to calculate the effect only from the weather conditions .
NOTE

7. (3.1)ground based measurement: Xianghe and Beijing 2014
4 and 7 Nov.
Separate the available time period into 3 parts
① before APEC:
16 Oct.---2 Nov.
② APEC: period :
3 Nov Nov.
③ after APEC:
13Nov Nov.
NO2 before, during and after APEC (measurement by ground-based MAX-DOAS in Xianghe and Beijing) .

8. (3.1)ground based measurement: Xianghe 2014
Temperature , Relative Humidity , wind speed and direction of Xianghe day by day before, during and after APEC.

9. (3.1)ground based measurement: Xianghe 2014
4 NOV.
5 NOV.
6 NOV.
7 NOV.
8 NOV.
9 NOV.

10. (3.1)ground based measurement: Xianghe, Beijing 2014
Averaged NO2 before, during and after APEC (measurement by ground-based MAX-DOAS in Xianghe and Beijing) .
VCD (1016molec.cm-2)
Compared to ‘Before APEC’(%)
Before APEC
APEC period
After APEC
Beijing NO2
5.2
100%
3.1
59.6%
5.6
107.7%(+7.7%)
Xianghe NO2
3.5
2.1
60.0%
4.6
131.4%(+31.4%)
Beijing SO2
3.7 4
4.7
Xianghe SO2
3.4
-40.4%
-40.0%
Compared to the ‘before APEC’, there is about 40% decrease for NO2 in the APEC period.

11. (3.1)ground based measurement: Xianghe, 2011--2014
Averaged NO2 of the same period in different years (measurement by ground-based MAX-DOAS in Xianghe and Beijing) .
VCD (1016molec.cm-2)
Before APEC
APEC period
After APEC
2011 NO2
3.6
4.4
5.3
2012 NO2
4.3
3.8
5.0
2013 NO2
3.9
3.5
Average NO2 of 2011—2013
4.1
4.6
2014 NO2
2.1
-10.3%
-48.8%
-0%
-40.0%

12. (3.1)ground based measurement: conclusion
So, based on the ground-based MAX-DOAS, there is an obvious reduction for NO2 during APEC period in Xianghe and Beijing, about -40% , no matter comparing with the same period of the last 3 years or with the ‘before APEC period’ in 2014.
Then, how about the result for Beijing and surrounding cities from satellite?

13. (3.2)satellite measurement: NO2 VCD, OMI 2011--2014
NO2 distribution in North China of the same period in different years (from OMI gridded data) .
2012
2013
2014

14. (3.2)satellite measurement:
NO2 VCD of minus that in the same period of 2014 from OMI.
The difference of NO2 between 2014 and 2011~2013 in North China of the same period (from OMI grid) .

15. (3.2)satellite measurement:
Averaged NO2 VCD of minus that in the same period of 2014 from OMI.
NO2 distribution in North China of the same period in different years (from OMI grid) . A:
Average of
2011~2013 B:
2014
Minus be divided by
(B-A)/A

16. (3.2)satellite measurement: NO2 OMI 2014B1 B2 B3 B:
2014
(B2-B1)/B1
(B3-B1)/B1
Minus be divided by

17. (3.2)satellite measurement: NO2 OMI 2011—2014
NO2 VCD (1016molec.cm-2)
Before APEC
APEC period
After APEC
Beijing
Average of
2.5
2.1
2.7
2014
1.9
1.4
2.4
Tianjin
2.3
3.1
1.7
Tangshan
2.6
2.8
Red :average of Blue: 2014
-33.3%
-26.3%
-26.1%
-10.5%
-39.1%
-50%

18. (3.2)satellite measurement: conclusion
From satellite data, there is also an obvious reduction for NO2 during APEC period in Beijing and its surroundings, about -30~-50% comparing with the same period of the last 3 years , and about -20~-40% comparing with the ‘before APEC period’ in 2014.
Then, how about the contribution for NO2 reduction from weather condition and Emission control, respectively?

19. (3.3)Model: to know the contribution for NO2 reduction only from weather condition, there is no change of the source emissions in the model setting. B1 B2 B3 B:
2014
(B2-B1)/B1
(B3-B1)/B1
Minus be divided by

20. (B2-B1)/B1 (3.4)compare results from satellite and model : B1:
before APEC
, 2014
B2:
APEC period
, 2014
satellite
model
Minus be divided by
satellite -model
Take Beijing for example, there is 31.1%(satellite) NO2 reduction, 7.6%(model) from the weather conditon and 23.4%(satellite-model) from the emission control.

21. (7)Conclusion
Based on the ground-based MAX-DOAS, there is an obvious reduction for NO2 during APEC period in Xianghe and Beijing, about -40% , no matter comparing with the same period of the last 3 years or with the ‘before APEC period’ in 2014.
From satellite data, about -30~-50% comparing with the same period of the last 3 years , and about -20~-40% comparing with the ‘before APEC period’ in 2014.
Most of the NO2 reduction is contributed by source emission control. Take Beijing for example, there is 31.1%(satellite) NO2 reduction, 7.6%(model) from the weather conditon and 23.4%(satellite-model) from the emission control.

22. 谢谢！
고맙습니다!
Thank you！
Merci !
ありがとう!
Danke!
Dankjewel!
Спасибо!