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This study examines the variation of NO2 levels over Beijing and its surrounding regions during the APEC 2014 period using ground-based measurements, satellite data, and modeling. The results show a significant decrease in NO2 concentrations during this time.
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Ting Wang1, François Hendrick2, PucaiWang1, Nan Hao3, Jianzhong Ma4, Lin Zhang5, Junli Jin4, Huan Yu2, and Michel Van Roozendael2 The Evolution of NO2 over Beijing and its vicinity during an extended period of APEC 2014 (1) Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences, Beijing, China (2) Belgian Institute for Space Aeronomy (IASB-BIRA), Brussels, Belgium (3) InstitutfürMethodikderFernerkundung (IMF), DeutschesZentrumfürLuft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany (4) Chinese Academy of Meteorological Sciences, Beijing, China (5) Peking University, , Beijing, China Brussels,2015-07-08 e-mail: wangting@mail.iap.ac.cn
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)
(1)background The Asia-Pacific Economic Cooperation (APEC) Meeting was hosted on 5-11 November 2014 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.
(1)background Air quality controls are necessary in Beijing and its surrounding. ?
(1)background Emission control Emission Control Period: Nov. 03-12, 2014 Emission Control Region: Beijing and surrounding provinces Emission Control Measures: Beijing: 50% vehicles restriction (Nov. 03 -12) closing construction sites (Nov. 03 -11) 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 closing heavy polluted factories From Beijing Municipal Environmental Protection Bureau: http://www.bjepb.gov.cn/
(2)data The datasets below were used to quantitatively describe the effect of the emission control and weather condition on NO2over Beijing and its vicinity during APEC period: (a) Xianghe MAX-DOAS : 16 Oct. ~ 30 Nov. , 2011—2014 . Xianghe meteorological data: 16 Oct. ~ 30 Nov. , 2011—2014 . Satellite data (OMI): 16 Oct. ~ 30 Nov. , 2011—2014 . Beijing MAX-DOAS : 16 Oct. ~ 30 Nov. , 2014. Model result (geo-chem): 16 Oct. ~ 30 Nov. , 2014 . 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
(3.1)ground based measurement: Xiangheand 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. ---12 Nov. ③ after APEC: 13Nov. ---30 Nov. NO2 before, during and after APEC (measurement by ground-based MAX-DOAS in Xianghe and Beijing) .
(3.1)ground based measurement: Xianghe 2014 Temperature , Relative Humidity , wind speed and direction of Xianghe day by day before, during and after APEC.
(3.1)ground based measurement: Xianghe 2014 6 NOV. 7 NOV. 5 NOV. 4 NOV. 8 NOV. 9 NOV.
(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) . -40.4% -40.0% Compared to the ‘before APEC’, there is about 40% decrease for NO2 in the APEC period.
(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) . -10.3% -48.8% -0% -40.0%
(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?
(3.2)satellite measurement: NO2 VCD, OMI 2011--2014 2011 NO2 distribution in North China of the same period in different years (from OMI gridded data) . 2012 2013 2014
(3.2)satellite measurement: NO2 VCD of 2011-2013 minus that in the same period of 2014 from OMI. 2011-2014 The difference of NO2 between 2014 and 2011~2013 in North China of the same period (from OMI grid) . 2012-2014 2013-2014
(3.2)satellite measurement: Averaged NO2 VCD of 2011-2013 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 (B-A)/A
(3.2)satellite measurement: NO2 OMI 2014 B1 B2 B3 B: 2014 (B2-B1)/B1 (B3-B1)/B1
(3.2)satellite measurement: NO2 OMI 2011—2014 Red :average of 2011--2013 Blue: 2014 -33.3% -26.3% -26.1% -10.5% -39.1% -50%
(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?
(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
(3.4)compare results from satellite and model : (B2-B1)/B1 B1: before APEC 10.16-11.2, 2014 B2: APEC period 11.3-11.12, 2014 satellite model 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.
(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.
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