2100) for the four different RCPs (2.6, 4.5, 6.0, and 8.5). The
simulations with the 1980 baseline-adjusted stratospheric
column ozone (time series from 1960 to 2100) over the
tropics (25° S–25° N) show a decrease in tropical lower
stratospheric ozone (100–30 hPa) and increase in the upper
stratosphere (Cionni et al. 2011). A summary of annual
mean trends is ozone in the troposphere and stratosphere
discussed above from observations, and CMIP5
multi-models future projections are listed in Table 5.1.
5.3.2 Emissions of Ozone Precursors
One of the largest uncertainties in modeling studies is
emission inventories. Global and regional emission inventories carry large uncertainties, especially in regions where
observational data are sparse. In this section, we provide a
brief overview of emissions of ozone precursors, e.g., NO x ,
CO, and NMVOCs, over India. Jena et al. (2015) reported
total NO x flux *1.5, 2.1, 2.4, 1.9, 1.7, and 1.4 Tg N year
−1
over India from six different inventories. Thermal power
plants contribute 30% of the total NO x emissions in India
(Garg et al. 2006). The total surface NO 2 emissions in India
are *3.5 Tg year
−1 in 1991 and *4.3 Tg year
−1 in 2001
(Beig and Brasseur 2006). The total NO x emissions in 2005
amount to *1.9 Tg N year
−1 (Ghude et al. 2013b). The
growth in oil and coal consumption resulted in a growth rate
of 3.8% ± 2.2% year
−1 between 2003 and 2011 for
anthropogenic NO x (Ghude et al. 2013a). This growth rate is
comparable with the estimate made by EDGAR (V4.2;
4.2% year
−1 ), GAINS (3.6% year
−1 ), or (Garg et al. 2006)
(4.4% year
−1 ) emission inventories. Sadavarte and
Venkataraman, (2014) reported estimates of NO x emissions
*5.6 (1.7–15.9) Tg year
−1 in 2015.
CO emissions show annual growth rate of 1.1% during
1985–2005 (Garg et al. 2006). The annual growth rate of CO
from the transport sector is *8.8% during 2001–2013
(Singh et al. 2017). The total CO emissions from India were
59.3 Tg year
−1 in 1991 and 69.4 Tg year
−1 in 2001 (Beig
and Brasseur 2006). The CO emission from wheat straw
burning in 2000 was 541 ± 387 Gg year
−1 (Sahai et al.
2007). Venkataraman et al. (2006) estimated *13–81 Gg
year
−1 of CO from biomass burning during 1995–2000. In
2000, CO emissions in India (63.3 Tg) were *23% of Asia
(279 Tg) (Streets et al. 2003).
Biogenic emissions are the largest natural source
(*90%) of volatile organic compounds (VOCs) in the
atmosphere (Guenther et al. 2006). The annual emissions of
VOCs in India from anthropogenic and biomass burning
sources were *10.8 Tg and 2.2 Tg, respectively, in 2000
(Streets et al. 2003). Total anthropogenic emissions of
non-methane volatile organic compounds (NMVOCs) were
9.81 Tg in 2010 (Sharma et al. 2015). The majority of
NMVOCs emissions (60%) originated from residential
combustion of biomass for cooking. Venkataraman et al.
(2006) estimated NMVOC emission *2.04–7.41 Tg year
−1
from biomass burning during 1995–2000 over India.
5.3.3 Trends of Tropospheric NO x , CO, NMVOCs,
and PAN
Trends in some of the ozone precursors (NO x , CO, VOCs)
are reported over the Indian region. Satellite observations
from GOME, GOME-2a, OMI, and SCIAMACHY during
2002–2011 show a trend of 2.20 ± 0.73% year
−1 in NO 2
volume mixing ratios over India (Mahajan et al. 2015).
While NO 2 volume mixing ratios from 1996 to 2006 showed
an increasing trend of 1.65 ± 0.52% year
−1 in over India.
The industrial regions of Mumbai and Delhi show increasing
trends of 2.1 ± 1.1 and 2.4 ± 1.2% year
−1 , respectively
(Ghude et al. 2008). CO observations from MOPITT
(Measurements of Pollution in the Troposphere) satellite
during 2000–2014 show contrasting trends in the lower and
upper troposphere. Estimated trends in lower-troposphere
and columnar CO are negative −2.0 to −3.4 ppb year
−1
(−1.1 to −2.0% year
−1 ) and positive 1.4–2.4 ppb year
−1
(1.8–3.2% year
−1 ) in the upper troposphere (Girach et al.
2017). AIRS/AMSU satellite (2003–2012) shows a 2%
increase in tropospheric CO concentration over the Indian
region (Ul-Haq et al. 2015) (Fig. 5.7a). Emission estimates
based on technology also show increasing trends *19 Tg
year
−1 , e.g. (Sadavarte and Venkataraman 2014). Peroxyacetyl nitrate (PAN) is formed in biomass burning plumes.
It is a secondary pollutant produced through the oxidation of
VOCs and NO X released from anthropogenic and biogenic
sources. Recent satellite observations show an increasing
trend in PAN *0.1 ± 0.05 to 2.7 ± 0.8 ppt year
−1 during
2005–2012 in the UTLS over Asia (Fadnavis et al. 2015)
(Fig. 5.7a). A significant increase in amounts of VOCs and
air pollutants is observed (May 2012) in the Indo-Gangetic
Plain (IGP). These observations show extremely high levels
of both VOCs and the primary air pollutants in the evening
and early morning hours in May 2012 (Fig. 5.7b). These
increasing levels of VOCs may be contributing to postive
trends in PAN in the UTLS. The observed trends in NO x and
PAN have high confidence, while CO and VOCs have low
confidence. Ozone and its precursor gases, PM 2.5 , PM 10 , are
being monitored since 2010 at various Indian stations by
System of Air Quality Forecasting and Research (SAFAR)
which is developed by the Indian Institute of Tropical
Meteorology. Long-term observations from SAFAR will be
helpful in obtaining future trends in ozone and its precursors over the India region.
106
S. Fadnavis et al.
simulations with the 1980 baseline-adjusted stratospheric
column ozone (time series from 1960 to 2100) over the
tropics (25° S–25° N) show a decrease in tropical lower
stratospheric ozone (100–30 hPa) and increase in the upper
stratosphere (Cionni et al. 2011). A summary of annual
mean trends is ozone in the troposphere and stratosphere
discussed above from observations, and CMIP5
multi-models future projections are listed in Table 5.1.
5.3.2 Emissions of Ozone Precursors
One of the largest uncertainties in modeling studies is
emission inventories. Global and regional emission inventories carry large uncertainties, especially in regions where
observational data are sparse. In this section, we provide a
brief overview of emissions of ozone precursors, e.g., NO x ,
CO, and NMVOCs, over India. Jena et al. (2015) reported
total NO x flux *1.5, 2.1, 2.4, 1.9, 1.7, and 1.4 Tg N year
−1
over India from six different inventories. Thermal power
plants contribute 30% of the total NO x emissions in India
(Garg et al. 2006). The total surface NO 2 emissions in India
are *3.5 Tg year
−1 in 1991 and *4.3 Tg year
−1 in 2001
(Beig and Brasseur 2006). The total NO x emissions in 2005
amount to *1.9 Tg N year
−1 (Ghude et al. 2013b). The
growth in oil and coal consumption resulted in a growth rate
of 3.8% ± 2.2% year
−1 between 2003 and 2011 for
anthropogenic NO x (Ghude et al. 2013a). This growth rate is
comparable with the estimate made by EDGAR (V4.2;
4.2% year
−1 ), GAINS (3.6% year
−1 ), or (Garg et al. 2006)
(4.4% year
−1 ) emission inventories. Sadavarte and
Venkataraman, (2014) reported estimates of NO x emissions
*5.6 (1.7–15.9) Tg year
−1 in 2015.
CO emissions show annual growth rate of 1.1% during
1985–2005 (Garg et al. 2006). The annual growth rate of CO
from the transport sector is *8.8% during 2001–2013
(Singh et al. 2017). The total CO emissions from India were
59.3 Tg year
−1 in 1991 and 69.4 Tg year
−1 in 2001 (Beig
and Brasseur 2006). The CO emission from wheat straw
burning in 2000 was 541 ± 387 Gg year
−1 (Sahai et al.
2007). Venkataraman et al. (2006) estimated *13–81 Gg
year
−1 of CO from biomass burning during 1995–2000. In
2000, CO emissions in India (63.3 Tg) were *23% of Asia
(279 Tg) (Streets et al. 2003).
Biogenic emissions are the largest natural source
(*90%) of volatile organic compounds (VOCs) in the
atmosphere (Guenther et al. 2006). The annual emissions of
VOCs in India from anthropogenic and biomass burning
sources were *10.8 Tg and 2.2 Tg, respectively, in 2000
(Streets et al. 2003). Total anthropogenic emissions of
non-methane volatile organic compounds (NMVOCs) were
9.81 Tg in 2010 (Sharma et al. 2015). The majority of
NMVOCs emissions (60%) originated from residential
combustion of biomass for cooking. Venkataraman et al.
(2006) estimated NMVOC emission *2.04–7.41 Tg year
−1
from biomass burning during 1995–2000 over India.
5.3.3 Trends of Tropospheric NO x , CO, NMVOCs,
and PAN
Trends in some of the ozone precursors (NO x , CO, VOCs)
are reported over the Indian region. Satellite observations
from GOME, GOME-2a, OMI, and SCIAMACHY during
2002–2011 show a trend of 2.20 ± 0.73% year
−1 in NO 2
volume mixing ratios over India (Mahajan et al. 2015).
While NO 2 volume mixing ratios from 1996 to 2006 showed
an increasing trend of 1.65 ± 0.52% year
−1 in over India.
The industrial regions of Mumbai and Delhi show increasing
trends of 2.1 ± 1.1 and 2.4 ± 1.2% year
−1 , respectively
(Ghude et al. 2008). CO observations from MOPITT
(Measurements of Pollution in the Troposphere) satellite
during 2000–2014 show contrasting trends in the lower and
upper troposphere. Estimated trends in lower-troposphere
and columnar CO are negative −2.0 to −3.4 ppb year
−1
(−1.1 to −2.0% year
−1 ) and positive 1.4–2.4 ppb year
−1
(1.8–3.2% year
−1 ) in the upper troposphere (Girach et al.
2017). AIRS/AMSU satellite (2003–2012) shows a 2%
increase in tropospheric CO concentration over the Indian
region (Ul-Haq et al. 2015) (Fig. 5.7a). Emission estimates
based on technology also show increasing trends *19 Tg
year
−1 , e.g. (Sadavarte and Venkataraman 2014). Peroxyacetyl nitrate (PAN) is formed in biomass burning plumes.
It is a secondary pollutant produced through the oxidation of
VOCs and NO X released from anthropogenic and biogenic
sources. Recent satellite observations show an increasing
trend in PAN *0.1 ± 0.05 to 2.7 ± 0.8 ppt year
−1 during
2005–2012 in the UTLS over Asia (Fadnavis et al. 2015)
(Fig. 5.7a). A significant increase in amounts of VOCs and
air pollutants is observed (May 2012) in the Indo-Gangetic
Plain (IGP). These observations show extremely high levels
of both VOCs and the primary air pollutants in the evening
and early morning hours in May 2012 (Fig. 5.7b). These
increasing levels of VOCs may be contributing to postive
trends in PAN in the UTLS. The observed trends in NO x and
PAN have high confidence, while CO and VOCs have low
confidence. Ozone and its precursor gases, PM 2.5 , PM 10 , are
being monitored since 2010 at various Indian stations by
System of Air Quality Forecasting and Research (SAFAR)
which is developed by the Indian Institute of Tropical
Meteorology. Long-term observations from SAFAR will be
helpful in obtaining future trends in ozone and its precursors over the India region.
106
S. Fadnavis et al.