during the decade of 1996–2005 (Soni et al. 2012). The
declining trend of all-sky global irradiance over India as a
whole was 0.6 W m
−2 year
−1 during 1971–2000 and
0.2 W m
−2 year
−1 during 2001–2010 (Soni et al. 2016). This
decrease in global irradiance is matched with an increase in
the diffused radiation over the same period indicating an
increase in the aerosol levels.
Efforts were taken to understand aerosol-cloud interaction
over the Indian region. The Cloud-Aerosol Interaction and
Precipitation Enhancement Experiment [CAIPEEX;
(Kulkarni et al. 2012)] has documented important processes
associated with aerosol-cloud interaction over the Indian
region. There is a significant increase in the cloud droplet
number concentration with an increase in aerosols (Kulkarni
et al. 2012). Very high aerosol loading causes narrowing of
the droplet spectrum, collision coalescence is suppressed,
and warm rain forms at an elevated layer (Konwar et al.
2012). During high aerosol loading conditions, clouds have
a large amount of super-cooled liquid water (>3 gm
−3 ) with
the dominant mixed-phase (Prabha et al. 2012).
Mixed-phase clouds contribute a significant part of monsoon
clouds, which are not understood completely and need further focused process studies. Aerosols acting as CCN, and
INP and their variability over the Indian region need further
observations and can be used for the models or fine-tune the
parameterization schemes.
Long-term observations of ozone (total column, vertical
profiles, and surface measurements) and its precursors (CO,
NO x , VOCs) have been studied to estimate linear trends over
the Indian region. Tropospheric ozone trends show spatiotemporal variations. Trend estimates vary with time due to
changes in the emission of precursors gases. In general,
ozone observations show increasing trends in the troposphere (0.7–0.9% year
−1 during 1979–2005) (high confidence) and decreasing trends in the stratosphere
(−0.05 ± 0.04 to −0.4 ± 0.1% year
−1 during 1993–2015)
(medium confidence). The reported ozone observations over
the Indian regions are of different time periods. However, the
System of Air Quality Forecasting and Research (SAFAR)
developed by the Indian Institute of Tropical Meteorology is
monitoring ozone and its precursors, since 2010. These
long-term observations will be helpful in obtaining future
ozone trends over the India region. The CMIP5 multi-model
future projections (the 2090s–2010s) over the tropics
(25° S–25° N) show that the annual mean ozone trend is
decreasing in the troposphere (except RCP8.5) and increasing in the stratosphere (Cionni et al. 2011). Seasonal trends
in the troposphere and stratosphere, both, are influenced by
emissions and, seasonal stratopheric intrusions, etc. The
reported ozone trends have low confidence. Long-range
transport processes (e.g., seasonal variations, transport
between extra-tropics and tropics, stratosphere and troposphere, etc.) produce a significant variation in the loading of
tropospheric ozone leading to large changes in radiative
forcing and dynamics. The model simulations show that
increased tropospheric ozone since pre-industrial times has
imposed ozone radiative forcing (at the tropopause) *0.2–
0.4 W m
−2 over the Indian region (Chalita et al. 1996).
References
Aneesh VR, Mohankumar G, Sampath S (2008) Spatial distribution of
atmospheric carbon monoxide over Bay of Bengal and Arabian Sea:
measurements during pre-monsoon period of 2006. J Earth Syst Sci
117:449–455. https://doi.org/10.1007/s12040-008-0044-8
Anil Kumar V, Pandithurai G, Parambil Leena P et al (2016)
Investigation of aerosol indirect effects on monsoon clouds using
ground-based measurements over a high-altitude site in Western
Ghats. Atmos Chem Phys 16:8423–8430. https://doi.org/10.5194/
acp-16-8423-2016
Babu SS, Satheesh SK, Moorthy KK (2002) Aerosol radiative forcing
due to enhanced black carbon at an urban site in India. Geophys Res
Lett 29:27-1–27-4. https://doi.org/10.1029/2002GL015826
Babu SS, Manoj MR, Moorthy KK et al (2013) Trends in aerosol
optical depth over Indian region: potential causes and impact
indicators. J Geophys Res Atmos 118:11794–11806. https://doi.org/
10.1002/2013JD020507
Badarinath KVS, Madhavi Latha K (2006) Direct radiative forcing
from black carbon aerosols over urban environment. Adv Sp Res
37:2183–2188. https://doi.org/10.1016/j.asr.2005.10.034
Beig G, Brasseur GP (2006) Influence of anthropogenic emissions on
tropospheric ozone and its precursors over the Indian tropical region
during a monsoon. Geophys Res Lett 33:1–5. https://doi.org/10.
1029/2005GL024949
Beig G, Singh V (2007) Trends in tropical tropospheric column ozone
from satellite data and MOZART model. Geophys Res Lett 34:1–5.
https://doi.org/10.1029/2007GL030460
Bera S, Prabha TV, Malap N et al (2019) Thermodynamics and
Microphysics Relation During CAIPEEX-I. Pure Appl Geophys
176:371–388. https://doi.org/10.1007/s00024-018-1942-6
Bharali C, Pathak B, Bhuyan PK (2015) Spring and summer night-time
high ozone episodes in the upper Brahmaputra valley of North East
India and their association with lightning. Atmos Environ 109:234–
250. https://doi.org/10.1016/j.atmosenv.2015.03.035
Bollasina MA, Ming Y, Ramaswamy V (2011) Anthropogenic aerosols
and the summer monsoon. Science 80(334):502–505
Bond TC, Doherty SJ, Fahey DW et al (2013) Bounding the role of
black carbon in the climate system: a scientific assessment.
J Geophys Res Atmos 118:5380–5552. https://doi.org/10.1002/
jgrd.50171
Brasseur GP, Orlando JJ, Tyndall GS, Atmospheric Research (U.S.)
NC (1999) Atmospheric chemistry and global change, topics in
environmental chemistry. Oxford University Press, New York
Brewer AW (1949) Evidence for a world circulation provided by the
measurements of helium and water vapour distribution in the
stratosphere. Q J R Meteorol Soc 75:351–363. https://doi.org/10.
1002/qj.49707532603
Chalita S, Hauglustaine DA, Le Treut H, Müller JF (1996) Radiative
forcing due to increased tropospheric ozone concentrations. Atmos
Environ 30:1641–1646. https://doi.org/10.1016/1352-2310(95)
00431-9
Chehade W, Weber M, Burrows JP (2014) Total ozone trends and
variability during 1979–2012 from merged data sets of various
satellites. Atmos Chem Phys 14:7059–7074. https://doi.org/10.
5194/acp-14-7059-2014
5 Atmospheric Aerosols and Trace Gases
111
declining trend of all-sky global irradiance over India as a
whole was 0.6 W m
−2 year
−1 during 1971–2000 and
0.2 W m
−2 year
−1 during 2001–2010 (Soni et al. 2016). This
decrease in global irradiance is matched with an increase in
the diffused radiation over the same period indicating an
increase in the aerosol levels.
Efforts were taken to understand aerosol-cloud interaction
over the Indian region. The Cloud-Aerosol Interaction and
Precipitation Enhancement Experiment [CAIPEEX;
(Kulkarni et al. 2012)] has documented important processes
associated with aerosol-cloud interaction over the Indian
region. There is a significant increase in the cloud droplet
number concentration with an increase in aerosols (Kulkarni
et al. 2012). Very high aerosol loading causes narrowing of
the droplet spectrum, collision coalescence is suppressed,
and warm rain forms at an elevated layer (Konwar et al.
2012). During high aerosol loading conditions, clouds have
a large amount of super-cooled liquid water (>3 gm
−3 ) with
the dominant mixed-phase (Prabha et al. 2012).
Mixed-phase clouds contribute a significant part of monsoon
clouds, which are not understood completely and need further focused process studies. Aerosols acting as CCN, and
INP and their variability over the Indian region need further
observations and can be used for the models or fine-tune the
parameterization schemes.
Long-term observations of ozone (total column, vertical
profiles, and surface measurements) and its precursors (CO,
NO x , VOCs) have been studied to estimate linear trends over
the Indian region. Tropospheric ozone trends show spatiotemporal variations. Trend estimates vary with time due to
changes in the emission of precursors gases. In general,
ozone observations show increasing trends in the troposphere (0.7–0.9% year
−1 during 1979–2005) (high confidence) and decreasing trends in the stratosphere
(−0.05 ± 0.04 to −0.4 ± 0.1% year
−1 during 1993–2015)
(medium confidence). The reported ozone observations over
the Indian regions are of different time periods. However, the
System of Air Quality Forecasting and Research (SAFAR)
developed by the Indian Institute of Tropical Meteorology is
monitoring ozone and its precursors, since 2010. These
long-term observations will be helpful in obtaining future
ozone trends over the India region. The CMIP5 multi-model
future projections (the 2090s–2010s) over the tropics
(25° S–25° N) show that the annual mean ozone trend is
decreasing in the troposphere (except RCP8.5) and increasing in the stratosphere (Cionni et al. 2011). Seasonal trends
in the troposphere and stratosphere, both, are influenced by
emissions and, seasonal stratopheric intrusions, etc. The
reported ozone trends have low confidence. Long-range
transport processes (e.g., seasonal variations, transport
between extra-tropics and tropics, stratosphere and troposphere, etc.) produce a significant variation in the loading of
tropospheric ozone leading to large changes in radiative
forcing and dynamics. The model simulations show that
increased tropospheric ozone since pre-industrial times has
imposed ozone radiative forcing (at the tropopause) *0.2–
0.4 W m
−2 over the Indian region (Chalita et al. 1996).
References
Aneesh VR, Mohankumar G, Sampath S (2008) Spatial distribution of
atmospheric carbon monoxide over Bay of Bengal and Arabian Sea:
measurements during pre-monsoon period of 2006. J Earth Syst Sci
117:449–455. https://doi.org/10.1007/s12040-008-0044-8
Anil Kumar V, Pandithurai G, Parambil Leena P et al (2016)
Investigation of aerosol indirect effects on monsoon clouds using
ground-based measurements over a high-altitude site in Western
Ghats. Atmos Chem Phys 16:8423–8430. https://doi.org/10.5194/
acp-16-8423-2016
Babu SS, Satheesh SK, Moorthy KK (2002) Aerosol radiative forcing
due to enhanced black carbon at an urban site in India. Geophys Res
Lett 29:27-1–27-4. https://doi.org/10.1029/2002GL015826
Babu SS, Manoj MR, Moorthy KK et al (2013) Trends in aerosol
optical depth over Indian region: potential causes and impact
indicators. J Geophys Res Atmos 118:11794–11806. https://doi.org/
10.1002/2013JD020507
Badarinath KVS, Madhavi Latha K (2006) Direct radiative forcing
from black carbon aerosols over urban environment. Adv Sp Res
37:2183–2188. https://doi.org/10.1016/j.asr.2005.10.034
Beig G, Brasseur GP (2006) Influence of anthropogenic emissions on
tropospheric ozone and its precursors over the Indian tropical region
during a monsoon. Geophys Res Lett 33:1–5. https://doi.org/10.
1029/2005GL024949
Beig G, Singh V (2007) Trends in tropical tropospheric column ozone
from satellite data and MOZART model. Geophys Res Lett 34:1–5.
https://doi.org/10.1029/2007GL030460
Bera S, Prabha TV, Malap N et al (2019) Thermodynamics and
Microphysics Relation During CAIPEEX-I. Pure Appl Geophys
176:371–388. https://doi.org/10.1007/s00024-018-1942-6
Bharali C, Pathak B, Bhuyan PK (2015) Spring and summer night-time
high ozone episodes in the upper Brahmaputra valley of North East
India and their association with lightning. Atmos Environ 109:234–
250. https://doi.org/10.1016/j.atmosenv.2015.03.035
Bollasina MA, Ming Y, Ramaswamy V (2011) Anthropogenic aerosols
and the summer monsoon. Science 80(334):502–505
Bond TC, Doherty SJ, Fahey DW et al (2013) Bounding the role of
black carbon in the climate system: a scientific assessment.
J Geophys Res Atmos 118:5380–5552. https://doi.org/10.1002/
jgrd.50171
Brasseur GP, Orlando JJ, Tyndall GS, Atmospheric Research (U.S.)
NC (1999) Atmospheric chemistry and global change, topics in
environmental chemistry. Oxford University Press, New York
Brewer AW (1949) Evidence for a world circulation provided by the
measurements of helium and water vapour distribution in the
stratosphere. Q J R Meteorol Soc 75:351–363. https://doi.org/10.
1002/qj.49707532603
Chalita S, Hauglustaine DA, Le Treut H, Müller JF (1996) Radiative
forcing due to increased tropospheric ozone concentrations. Atmos
Environ 30:1641–1646. https://doi.org/10.1016/1352-2310(95)
00431-9
Chehade W, Weber M, Burrows JP (2014) Total ozone trends and
variability during 1979–2012 from merged data sets of various
satellites. Atmos Chem Phys 14:7059–7074. https://doi.org/10.
5194/acp-14-7059-2014
5 Atmospheric Aerosols and Trace Gases
111