SO 2 emissions by Xia et al. (2016) are smaller than MEIC, the inventory of
Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS, Klimont
et al. 2009), the Regional Emission inventory in ASia (REAS, Kurokawa et al.
2013), and the estimates by Lu et al. (2011). GAINS estimated the application rates
of FGD in the power sector at 28% and 56% for existing and newly built units in
2010, respectively, smaller than 86% applied in Xia et al. (2016). REAS provided
relatively large emission factors and thereby emissions, even with less energy
consumption applied than other inventories (Lu et al. 2011; Zhao et al. 2011a).
The largest discrepancy between Lu et al. (2011) and Xia et al. (2016) existed in
industrial sectors. The emissions of industry were calculated at 20.4 and 11.6 Mt for
the two studies in 2010, respectively, indicating weaker control of SO 2 emissions for
industries assumed by Lu et al. (2011). The estimates by Xia et al. (2016) are close to
EDGAR for earlier years, but enhanced discrepancy was found after 2005, implying
that the efforts of SO 2 control after 2005 might not fully be included in EDGAR. For
NO X , the estimates by Xia et al. (2016) agree well with MEIC and REAS inventories
but are larger than the estimates in GAINS and EDGAR. The differences come
mainly from various emission factors used in different studies. For example, Xia
et al. (2016) assumed very little change in NO X emission factors for existing power
plants, while GAINS estimated a 13% reduction of the emission factor (Klimont
et al. 2009).
14.3 Evaluation from Satellite Observation and Policy
Implications
14.3.1 Comparison Between the Emissions and SatelliteDerived VCDs
Tropospheric vertical column densities (VCDs) observed from satellite have been
applied to evaluate the inter-annual variation in emissions and to indicate the effects
of national regulations on pollution control. Based on the observation from ozone
monitoring instrument (OMI), for example, Li et al. (2017a) estimated the planetary
boundary layer (PBL) column densities of SO 2 for Asia and found substantial
reduction in China’s SO 2 from 2005 to 2016 (Fig. 14.3). The benefits of national
regulation on SO 2 control could thus be clearly revealed.
Xia et al. (2016) compared the inter-annual trends in the estimated national
emissions and satellite-retrieved VCD for SO 2 and NO X from 2005 to 2014. The
daily PBL SO 2 VCDs are obtained from the OMSO2 Level-3 products by NASA’s
Goddard Earth Sciences Data and Information Services Center (GES-DISC, http://
disc.sci.gsfc.nasa.gov/Aura/data-holdings/OMI/omso2e_v003.shtml) at a spatial
resolution of 0.25 Â 0.25
. Monthly average VCDs are then calculated from the
daily data product. Tropospheric NO 2 VCDs are retrieved from OMI by the Royal
Netherlands Meteorological Institute (KNMI), and the monthly data with a spatial
14 National Regulation of SO 2 and NO x Emissions in China
321
Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS, Klimont
et al. 2009), the Regional Emission inventory in ASia (REAS, Kurokawa et al.
2013), and the estimates by Lu et al. (2011). GAINS estimated the application rates
of FGD in the power sector at 28% and 56% for existing and newly built units in
2010, respectively, smaller than 86% applied in Xia et al. (2016). REAS provided
relatively large emission factors and thereby emissions, even with less energy
consumption applied than other inventories (Lu et al. 2011; Zhao et al. 2011a).
The largest discrepancy between Lu et al. (2011) and Xia et al. (2016) existed in
industrial sectors. The emissions of industry were calculated at 20.4 and 11.6 Mt for
the two studies in 2010, respectively, indicating weaker control of SO 2 emissions for
industries assumed by Lu et al. (2011). The estimates by Xia et al. (2016) are close to
EDGAR for earlier years, but enhanced discrepancy was found after 2005, implying
that the efforts of SO 2 control after 2005 might not fully be included in EDGAR. For
NO X , the estimates by Xia et al. (2016) agree well with MEIC and REAS inventories
but are larger than the estimates in GAINS and EDGAR. The differences come
mainly from various emission factors used in different studies. For example, Xia
et al. (2016) assumed very little change in NO X emission factors for existing power
plants, while GAINS estimated a 13% reduction of the emission factor (Klimont
et al. 2009).
14.3 Evaluation from Satellite Observation and Policy
Implications
14.3.1 Comparison Between the Emissions and SatelliteDerived VCDs
Tropospheric vertical column densities (VCDs) observed from satellite have been
applied to evaluate the inter-annual variation in emissions and to indicate the effects
of national regulations on pollution control. Based on the observation from ozone
monitoring instrument (OMI), for example, Li et al. (2017a) estimated the planetary
boundary layer (PBL) column densities of SO 2 for Asia and found substantial
reduction in China’s SO 2 from 2005 to 2016 (Fig. 14.3). The benefits of national
regulation on SO 2 control could thus be clearly revealed.
Xia et al. (2016) compared the inter-annual trends in the estimated national
emissions and satellite-retrieved VCD for SO 2 and NO X from 2005 to 2014. The
daily PBL SO 2 VCDs are obtained from the OMSO2 Level-3 products by NASA’s
Goddard Earth Sciences Data and Information Services Center (GES-DISC, http://
disc.sci.gsfc.nasa.gov/Aura/data-holdings/OMI/omso2e_v003.shtml) at a spatial
resolution of 0.25 Â 0.25
. Monthly average VCDs are then calculated from the
daily data product. Tropospheric NO 2 VCDs are retrieved from OMI by the Royal
Netherlands Meteorological Institute (KNMI), and the monthly data with a spatial
14 National Regulation of SO 2 and NO x Emissions in China
321