We describe and show results from a series of field campaigns that used balloonborne instruments ... more We describe and show results from a series of field campaigns that used balloonborne instruments launched from India and Saudi Arabia during the summers 2014–17 to study the nature, formation, and impacts of the Asian Tropopause Aerosol Layer (ATAL). The campaign goals were to i) characterize the optical, physical, and chemical properties of the ATAL; ii) assess its impacts on water vapor and ozone; and iii) understand the role of convection in its formation. To address these objectives, we launched 68 balloons from four locations, one in Saudi Arabia and three in India, with payload weights ranging from 1.5 to 50 kg. We measured meteorological parameters; ozone; water vapor; and aerosol backscatter, concentration, volatility, and composition in the upper troposphere and lower stratosphere (UTLS) region. We found peaks in aerosol concentrations of up to 25 cm–3 for radii > 94 nm, associated with a scattering ratio at 940 nm of ∼1.9 near the cold-point tropopause. During medium-du...
S. Tiwari, Philip K. Hopke, A.S. Pipal, A.K. Srivastava, D.S. Bisht,
Shani Tiwari, A.K. Singh, V.... more S. Tiwari, Philip K. Hopke, A.S. Pipal, A.K. Srivastava, D.S. Bisht, Shani Tiwari, A.K. Singh, V.K. Soni, S.D. Attri
The aerosols in the Indo-Gangetic Basin (IGB) are
a mixture of sulfate, dust, black carbon, and o... more The aerosols in the Indo-Gangetic Basin (IGB) are a mixture of sulfate, dust, black carbon, and other soluble and insoluble components. It is a challenge not only to identify these various aerosol types, but also to assess the optical and radiative implications of these components. In the present study, appropriate thresholds for fine-mode fraction and single-scattering albedo have been used to first identify the aerosol types over IGB. Four major aerosol types may be identified as polluted dust (PD), polluted continental (PC), black carbon-enriched (BCE), and organic carbon-enriched (OCE). Further, the implications of these different types of aerosols on optical properties and radiative forcing have been studied. The aerosol products derived from CIMEL sun/sky radiometer measurements, deployed under Aerosol Robotic Network program of NASA, USA were used from four different sites Karachi, Lahore, Jaipur, and Kanpur, spread over Pakistan and Northern India. PD is the most dominant aerosol type at Karachi and Jaipur, contributing more than 50 % of all the aerosol types. OCE, on the other hand, contributes only about 12–15 % at all the stations except at Kanpur where its contribution is∼38 %. The spectral dependence of AOD was relatively low for PD aerosol type, with the lowest AE values (<0.5); whereas, large spectral dependence in AOD was observed for the remaining aerosol types, with the highest AE values (>1.0). SSA was found to be the highest for OCE (>0.9) and the lowest for BCE (<0.9) type aerosols, with drastically different spectral variability. The direct aerosol radiative forcing at the surface and in the atmosphere was found to be the maximum at Lahore among all the four stations in the IGB
Black carbon (BC) aerosols, which are optically absorbing parts of carbonaceous aerosols and have... more Black carbon (BC) aerosols, which are optically absorbing parts of carbonaceous aerosols and have significantly different optical and radiative properties were continuously measured at a coalfield area in Dhanbad (23° 47′N, 86° 30′E: 222 m amsl), India for thefirst time from 1st January to 31st December, 2012. Daily BC mass concentrations varied within the range of 0.84–17.0μgm −3 with an annual average of 6.3 ± 2.7μgm −3 . About 45% of samples of the measured days exceeded the mean level of BC indicating the high loading of soot particles over the study region. Intra-seasonal variation in BC concentrations exhibited a strong seasonal cycle with the highest concentrations during winter (8.2 ± 2.8μgm −3 ), followed by post-monsoon (6.4 ± 2.6μgm −3 ), pre-monsoon (5.5 ± 1.9μgm −3 ) and monsoon (4.6 ± 1.7μgm −3 ). In diurnal analysis, BC showed a significant peak from 06:00 to 10:00 local time (LT) during all the seasons whereas the lowest concentrations were found during 14:00 to 17:00 LT in the late afternoon. The difference between maximum and minimum concentrations of BC was found to be higher during winter (8.3μgm −3 ) followed by post-monsoon (4.7μgm −3 ), pre-monsoon (4.3μgm −3 ) and monsoon (1.7μgm −3 ). An interesting feature was seen in the difference between morning and evening peaks, it was maximum during winter (4.8μgm −3 ) followed by pre-monsoon (1.5μgm −3 )andpost-monsoon (1.3μgm −3 ), however, during monsoon, it was opposite i.e. ~23% lower during morning time. During day-time and night-time variability analyses, itfluctuated largely, varying from 1% (December) to 35% (June) higher during night-time as compared to day-time as whole mean was ~19%. Data of BC were separated as stable (b1ms −1 )and unstable weather conditions (N1ms −1 ), the corresponding values of BC were 6.06 and 3.75μgm −3 respectively which is ~38% higher during stable weather condition indicating that the major portion of BC was mainly emitted from local sources instead of transported from remote sources. Apart from this, it was observed that the concentration of BC mass during winter was ~78% higher (8.2μgm −3 ) as compared to monsoon (4.6μgm −3 ) when the winds were from the SE (158°) direction.
Because of high emissions of anthropogenic as well
as natural particles over the Indo-Gangetic Pl... more Because of high emissions of anthropogenic as well as natural particles over the Indo-Gangetic Plains (IGP), it is important to study the characteristics of fine (PM2.5)and inhalable particles (PM10), including their morphology, physical and chemical characteristics, etc., in Delhi during winter 2013. The mean mass concentrations of fine (PM2.5)and inhalable (PM10) (continuous) was 117.6±79.1 and 191.0± 127.6μgm−3 , respectively, whereas the coarse mode (PM10–2.5) particle PM mass was 73.38±28.5 μgm−3 . During the same period, offline gravimetric monitoring of PM2.5was conducted for morphological analysis, and its concentration was ~37 % higher compared to the continuous measurement. Carbonaceous PM such as organic carbon (OC) and elemental carbon (EC) were analyzed on the collected filters, and their mean concentration was respectively 33.8 and 4.0μgm −3 during the daytime, while at night it was 41.2 and 10.1μgm −3 , respectively. The average OC/EC ratio was 8.97 and 3.96 during the day and night, respectively, indicating the formation of secondary organic aerosols during daytime. Effective carbon ratio was studied to see the effect of aerosols on climate, and its mean value was 0.52 and 1.79 during night and day, indicating the dominance of absorbing and scattering types of aerosols respectively into the atmosphere over the study region. Elemental analysis of individual particles indicates that Si is the most abundant element (~37–90 %), followed by O (oxide) and Al. Circularity and aspect ratio was studied, which indicates that particles are not perfectly spherical and not elongated in any direction. Trajectory analysis indicated that in the months of February and March, air masses appear to be transported from the Middle Eastern part along with neighboring countries and over Thar Desert region, while in January it was from the northeast direction which resulted in high concentrations of fine particles
action; wintertime aerosol (January, 1 to March, 31, 2014 (n¼90)) were measured in middle IGP in ... more action; wintertime aerosol (January, 1 to March, 31, 2014 (n¼90)) were measured in middle IGP in terms of aerosol mass loading, optical properties, altitudinal distributions and both high and low altitude transportation. Both space-borne passive (Aqua and Terra MODIS) and active sensor (CALIPSO-CALIOP) based measurements were concurrently used over the selected transect (25
10 0e25
19 0 N and 82 54 0 e83
4 0E). Exceptionally high aerosol mass loading was recorded for PM10(233±58.37mgm 3) and PM2.5 (138±47.12mgm 3). Daily variations of PM2.5/PM10persist in a range of 0.25e0.97 (mean¼0.60±0.14; n¼90) and were in accordance to computed Angstrom exponent (0.078e1.407; mean: 1.002±0.254) explaining concurrent contribution of both PM2.5and PM10for the region. Space borne (Aqua MODISAOD: 0.259e2.194) and ground based (MTP-AOD: 0.066e1.239) AODs revealed significant temporal variability and moderate association in terms of PM10 (MODIS-AOD: 0.46; MTP-AOD: 0.56) and PM2.5 (MODIS-AOD: 0.54; MTP-AOD: 0.39). Varying association of AOD and aerosol mass loading was also explained in terms of meteorological variables. CALIPSO altitude-orbit-cross-section profiles revealed presence of non-spherical coarse particulates (altitude: 1.2e5.4 km) and dominance of sphericalfine particulates (altitude: 0.1e4.2 km). Contribution of trans-boundary aerosols transportation to mass loadings at middle IGP were recognized through lagrangian particle dispersion model, synoptic vector wind profiles at different geopotential heights and satellite images
Atmospheric aerosol consists of both natural and anthropogenic origin. Studies have sh... more Atmospheric aerosol consists of both natural and anthropogenic origin. Studies have shown that continuous exposure to these particles is associated with a high percentage of death from respiratory and cardiovascular disease. In the present study, we have first time used both SEM -EDX analysis as well as chemical analysis to understand the differences in morphology and elemental composition of aerosols sample from a suburban clean and green area of Banaras Hindu University campus and some much polluted urban areas of the Varanasi city situated in the eastern Indo-Gangetic plain. The analysis was done by using scanning electron microscope (SEM) coupled with energy dispersive X-ray microanalyzer (EDX) and ionchromatography (IC). Analyses show that C, Ca, Na, S, Si, Al have dominated the sample s. The concentration for urban areas of city were more than the pollution of suburban area and followed the trend as Na + > SO 4 2-> Ca 2+ > Cl -> Mg 2+ > NO 3 -> K + > HCO3 + > F -, where as for suburban area showed the trend as Na + > SO 4 2-> NO3 -> Ca 2+ > Cl -> Mg 2+ > K + > HCO3 + > F -. This shows that more polluted urban areas were dominated by soil-dust generated due to heavy traffic movement and construction/industries. To establish differences among sites more measurements are necessary in different meteorological conditions.
We describe and show results from a series of field campaigns that used balloonborne instruments ... more We describe and show results from a series of field campaigns that used balloonborne instruments launched from India and Saudi Arabia during the summers 2014–17 to study the nature, formation, and impacts of the Asian Tropopause Aerosol Layer (ATAL). The campaign goals were to i) characterize the optical, physical, and chemical properties of the ATAL; ii) assess its impacts on water vapor and ozone; and iii) understand the role of convection in its formation. To address these objectives, we launched 68 balloons from four locations, one in Saudi Arabia and three in India, with payload weights ranging from 1.5 to 50 kg. We measured meteorological parameters; ozone; water vapor; and aerosol backscatter, concentration, volatility, and composition in the upper troposphere and lower stratosphere (UTLS) region. We found peaks in aerosol concentrations of up to 25 cm–3 for radii > 94 nm, associated with a scattering ratio at 940 nm of ∼1.9 near the cold-point tropopause. During medium-du...
S. Tiwari, Philip K. Hopke, A.S. Pipal, A.K. Srivastava, D.S. Bisht,
Shani Tiwari, A.K. Singh, V.... more S. Tiwari, Philip K. Hopke, A.S. Pipal, A.K. Srivastava, D.S. Bisht, Shani Tiwari, A.K. Singh, V.K. Soni, S.D. Attri
The aerosols in the Indo-Gangetic Basin (IGB) are
a mixture of sulfate, dust, black carbon, and o... more The aerosols in the Indo-Gangetic Basin (IGB) are a mixture of sulfate, dust, black carbon, and other soluble and insoluble components. It is a challenge not only to identify these various aerosol types, but also to assess the optical and radiative implications of these components. In the present study, appropriate thresholds for fine-mode fraction and single-scattering albedo have been used to first identify the aerosol types over IGB. Four major aerosol types may be identified as polluted dust (PD), polluted continental (PC), black carbon-enriched (BCE), and organic carbon-enriched (OCE). Further, the implications of these different types of aerosols on optical properties and radiative forcing have been studied. The aerosol products derived from CIMEL sun/sky radiometer measurements, deployed under Aerosol Robotic Network program of NASA, USA were used from four different sites Karachi, Lahore, Jaipur, and Kanpur, spread over Pakistan and Northern India. PD is the most dominant aerosol type at Karachi and Jaipur, contributing more than 50 % of all the aerosol types. OCE, on the other hand, contributes only about 12–15 % at all the stations except at Kanpur where its contribution is∼38 %. The spectral dependence of AOD was relatively low for PD aerosol type, with the lowest AE values (<0.5); whereas, large spectral dependence in AOD was observed for the remaining aerosol types, with the highest AE values (>1.0). SSA was found to be the highest for OCE (>0.9) and the lowest for BCE (<0.9) type aerosols, with drastically different spectral variability. The direct aerosol radiative forcing at the surface and in the atmosphere was found to be the maximum at Lahore among all the four stations in the IGB
Black carbon (BC) aerosols, which are optically absorbing parts of carbonaceous aerosols and have... more Black carbon (BC) aerosols, which are optically absorbing parts of carbonaceous aerosols and have significantly different optical and radiative properties were continuously measured at a coalfield area in Dhanbad (23° 47′N, 86° 30′E: 222 m amsl), India for thefirst time from 1st January to 31st December, 2012. Daily BC mass concentrations varied within the range of 0.84–17.0μgm −3 with an annual average of 6.3 ± 2.7μgm −3 . About 45% of samples of the measured days exceeded the mean level of BC indicating the high loading of soot particles over the study region. Intra-seasonal variation in BC concentrations exhibited a strong seasonal cycle with the highest concentrations during winter (8.2 ± 2.8μgm −3 ), followed by post-monsoon (6.4 ± 2.6μgm −3 ), pre-monsoon (5.5 ± 1.9μgm −3 ) and monsoon (4.6 ± 1.7μgm −3 ). In diurnal analysis, BC showed a significant peak from 06:00 to 10:00 local time (LT) during all the seasons whereas the lowest concentrations were found during 14:00 to 17:00 LT in the late afternoon. The difference between maximum and minimum concentrations of BC was found to be higher during winter (8.3μgm −3 ) followed by post-monsoon (4.7μgm −3 ), pre-monsoon (4.3μgm −3 ) and monsoon (1.7μgm −3 ). An interesting feature was seen in the difference between morning and evening peaks, it was maximum during winter (4.8μgm −3 ) followed by pre-monsoon (1.5μgm −3 )andpost-monsoon (1.3μgm −3 ), however, during monsoon, it was opposite i.e. ~23% lower during morning time. During day-time and night-time variability analyses, itfluctuated largely, varying from 1% (December) to 35% (June) higher during night-time as compared to day-time as whole mean was ~19%. Data of BC were separated as stable (b1ms −1 )and unstable weather conditions (N1ms −1 ), the corresponding values of BC were 6.06 and 3.75μgm −3 respectively which is ~38% higher during stable weather condition indicating that the major portion of BC was mainly emitted from local sources instead of transported from remote sources. Apart from this, it was observed that the concentration of BC mass during winter was ~78% higher (8.2μgm −3 ) as compared to monsoon (4.6μgm −3 ) when the winds were from the SE (158°) direction.
Because of high emissions of anthropogenic as well
as natural particles over the Indo-Gangetic Pl... more Because of high emissions of anthropogenic as well as natural particles over the Indo-Gangetic Plains (IGP), it is important to study the characteristics of fine (PM2.5)and inhalable particles (PM10), including their morphology, physical and chemical characteristics, etc., in Delhi during winter 2013. The mean mass concentrations of fine (PM2.5)and inhalable (PM10) (continuous) was 117.6±79.1 and 191.0± 127.6μgm−3 , respectively, whereas the coarse mode (PM10–2.5) particle PM mass was 73.38±28.5 μgm−3 . During the same period, offline gravimetric monitoring of PM2.5was conducted for morphological analysis, and its concentration was ~37 % higher compared to the continuous measurement. Carbonaceous PM such as organic carbon (OC) and elemental carbon (EC) were analyzed on the collected filters, and their mean concentration was respectively 33.8 and 4.0μgm −3 during the daytime, while at night it was 41.2 and 10.1μgm −3 , respectively. The average OC/EC ratio was 8.97 and 3.96 during the day and night, respectively, indicating the formation of secondary organic aerosols during daytime. Effective carbon ratio was studied to see the effect of aerosols on climate, and its mean value was 0.52 and 1.79 during night and day, indicating the dominance of absorbing and scattering types of aerosols respectively into the atmosphere over the study region. Elemental analysis of individual particles indicates that Si is the most abundant element (~37–90 %), followed by O (oxide) and Al. Circularity and aspect ratio was studied, which indicates that particles are not perfectly spherical and not elongated in any direction. Trajectory analysis indicated that in the months of February and March, air masses appear to be transported from the Middle Eastern part along with neighboring countries and over Thar Desert region, while in January it was from the northeast direction which resulted in high concentrations of fine particles
action; wintertime aerosol (January, 1 to March, 31, 2014 (n¼90)) were measured in middle IGP in ... more action; wintertime aerosol (January, 1 to March, 31, 2014 (n¼90)) were measured in middle IGP in terms of aerosol mass loading, optical properties, altitudinal distributions and both high and low altitude transportation. Both space-borne passive (Aqua and Terra MODIS) and active sensor (CALIPSO-CALIOP) based measurements were concurrently used over the selected transect (25
10 0e25
19 0 N and 82 54 0 e83
4 0E). Exceptionally high aerosol mass loading was recorded for PM10(233±58.37mgm 3) and PM2.5 (138±47.12mgm 3). Daily variations of PM2.5/PM10persist in a range of 0.25e0.97 (mean¼0.60±0.14; n¼90) and were in accordance to computed Angstrom exponent (0.078e1.407; mean: 1.002±0.254) explaining concurrent contribution of both PM2.5and PM10for the region. Space borne (Aqua MODISAOD: 0.259e2.194) and ground based (MTP-AOD: 0.066e1.239) AODs revealed significant temporal variability and moderate association in terms of PM10 (MODIS-AOD: 0.46; MTP-AOD: 0.56) and PM2.5 (MODIS-AOD: 0.54; MTP-AOD: 0.39). Varying association of AOD and aerosol mass loading was also explained in terms of meteorological variables. CALIPSO altitude-orbit-cross-section profiles revealed presence of non-spherical coarse particulates (altitude: 1.2e5.4 km) and dominance of sphericalfine particulates (altitude: 0.1e4.2 km). Contribution of trans-boundary aerosols transportation to mass loadings at middle IGP were recognized through lagrangian particle dispersion model, synoptic vector wind profiles at different geopotential heights and satellite images
Atmospheric aerosol consists of both natural and anthropogenic origin. Studies have sh... more Atmospheric aerosol consists of both natural and anthropogenic origin. Studies have shown that continuous exposure to these particles is associated with a high percentage of death from respiratory and cardiovascular disease. In the present study, we have first time used both SEM -EDX analysis as well as chemical analysis to understand the differences in morphology and elemental composition of aerosols sample from a suburban clean and green area of Banaras Hindu University campus and some much polluted urban areas of the Varanasi city situated in the eastern Indo-Gangetic plain. The analysis was done by using scanning electron microscope (SEM) coupled with energy dispersive X-ray microanalyzer (EDX) and ionchromatography (IC). Analyses show that C, Ca, Na, S, Si, Al have dominated the sample s. The concentration for urban areas of city were more than the pollution of suburban area and followed the trend as Na + > SO 4 2-> Ca 2+ > Cl -> Mg 2+ > NO 3 -> K + > HCO3 + > F -, where as for suburban area showed the trend as Na + > SO 4 2-> NO3 -> Ca 2+ > Cl -> Mg 2+ > K + > HCO3 + > F -. This shows that more polluted urban areas were dominated by soil-dust generated due to heavy traffic movement and construction/industries. To establish differences among sites more measurements are necessary in different meteorological conditions.
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Papers by Shani Tiwari
Shani Tiwari, A.K. Singh, V.K. Soni, S.D. Attri
a mixture of sulfate, dust, black carbon, and other soluble and
insoluble components. It is a challenge not only to identify
these various aerosol types, but also to assess the optical and
radiative implications of these components. In the present
study, appropriate thresholds for fine-mode fraction and
single-scattering albedo have been used to first identify the
aerosol types over IGB. Four major aerosol types may be
identified as polluted dust (PD), polluted continental (PC),
black carbon-enriched (BCE), and organic carbon-enriched
(OCE). Further, the implications of these different types of
aerosols on optical properties and radiative forcing have been
studied. The aerosol products derived from CIMEL sun/sky
radiometer measurements, deployed under Aerosol Robotic
Network program of NASA, USA were used from four different sites Karachi, Lahore, Jaipur, and Kanpur, spread over
Pakistan and Northern India. PD is the most dominant aerosol
type at Karachi and Jaipur, contributing more than 50 % of all
the aerosol types. OCE, on the other hand, contributes only
about 12–15 % at all the stations except at Kanpur where its
contribution is∼38 %. The spectral dependence of AOD was
relatively low for PD aerosol type, with the lowest AE values
(<0.5); whereas, large spectral dependence in AOD was observed for the remaining aerosol types, with the highest
AE values (>1.0). SSA was found to be the highest for OCE
(>0.9) and the lowest for BCE (<0.9) type aerosols, with drastically different spectral variability. The direct aerosol radiative forcing at the surface and in the atmosphere was found to be the maximum at Lahore among all the four stations in the
IGB
different optical and radiative properties were continuously measured at a coalfield area in Dhanbad (23° 47′N,
86° 30′E: 222 m amsl), India for thefirst time from 1st January to 31st December, 2012. Daily BC mass concentrations varied within the range of 0.84–17.0μgm
−3
with an annual average of 6.3 ± 2.7μgm
−3
. About 45% of samples of the measured days exceeded the mean level of BC indicating the high loading of soot particles over the study
region. Intra-seasonal variation in BC concentrations exhibited a strong seasonal cycle with the highest concentrations during winter (8.2 ± 2.8μgm
−3
), followed by post-monsoon (6.4 ± 2.6μgm
−3
), pre-monsoon (5.5 ±
1.9μgm
−3
) and monsoon (4.6 ± 1.7μgm
−3
). In diurnal analysis, BC showed a significant peak from 06:00 to
10:00 local time (LT) during all the seasons whereas the lowest concentrations were found during 14:00 to
17:00 LT in the late afternoon. The difference between maximum and minimum concentrations of BC was found
to be higher during winter (8.3μgm
−3
) followed by post-monsoon (4.7μgm
−3
), pre-monsoon (4.3μgm
−3
)
and monsoon (1.7μgm
−3
). An interesting feature was seen in the difference between morning and evening
peaks, it was maximum during winter (4.8μgm
−3
) followed by pre-monsoon (1.5μgm
−3
)andpost-monsoon
(1.3μgm
−3
), however, during monsoon, it was opposite i.e. ~23% lower during morning time. During day-time
and night-time variability analyses, itfluctuated largely, varying from 1% (December) to 35% (June) higher during
night-time as compared to day-time as whole mean was ~19%. Data of BC were separated as stable (b1ms
−1
)and
unstable weather conditions (N1ms
−1
), the corresponding values of BC were 6.06 and 3.75μgm
−3
respectively
which is ~38% higher during stable weather condition indicating that the major portion of BC was mainly emitted
from local sources instead of transported from remote sources. Apart from this, it was observed that the concentration of BC mass during winter was ~78% higher (8.2μgm
−3
) as compared to monsoon (4.6μgm
−3
) when the
winds were from the SE (158°) direction.
as natural particles over the Indo-Gangetic Plains (IGP), it is
important to study the characteristics of fine (PM2.5)and
inhalable particles (PM10), including their morphology, physical and chemical characteristics, etc., in Delhi during winter
2013. The mean mass concentrations of fine (PM2.5)and
inhalable (PM10) (continuous) was 117.6±79.1 and 191.0±
127.6μgm−3
, respectively, whereas the coarse mode
(PM10–2.5) particle PM mass was 73.38±28.5 μgm−3
.
During the same period, offline gravimetric monitoring of
PM2.5was conducted for morphological analysis, and its concentration was ~37 % higher compared to the continuous
measurement. Carbonaceous PM such as organic carbon (OC) and elemental carbon (EC) were analyzed on the collected filters, and their mean concentration was respectively 33.8 and 4.0μgm
−3
during the daytime, while at night it was 41.2
and 10.1μgm
−3
, respectively. The average OC/EC ratio was
8.97 and 3.96 during the day and night, respectively, indicating the formation of secondary organic aerosols during daytime. Effective carbon ratio was studied to see the effect of
aerosols on climate, and its mean value was 0.52 and 1.79
during night and day, indicating the dominance of absorbing
and scattering types of aerosols respectively into the atmosphere over the study region. Elemental analysis of individual
particles indicates that Si is the most abundant element
(~37–90 %), followed by O (oxide) and Al. Circularity and
aspect ratio was studied, which indicates that particles are not
perfectly spherical and not elongated in any direction.
Trajectory analysis indicated that in the months of February
and March, air masses appear to be transported from the
Middle Eastern part along with neighboring countries and
over Thar Desert region, while in January it was from the
northeast direction which resulted in high concentrations of
fine particles
of aerosol mass loading, optical properties, altitudinal distributions and both high and low altitude
transportation. Both space-borne passive (Aqua and Terra MODIS) and active sensor (CALIPSO-CALIOP)
based measurements were concurrently used over the selected transect (25
10
0e25
19
0
N and 82
54
0
e83
4
0E). Exceptionally high aerosol mass loading was recorded for PM10(233±58.37mgm
3) and PM2.5
(138±47.12mgm
3). Daily variations of PM2.5/PM10persist in a range of 0.25e0.97 (mean¼0.60±0.14;
n¼90) and were in accordance to computed Angstrom exponent (0.078e1.407; mean: 1.002±0.254)
explaining concurrent contribution of both PM2.5and PM10for the region. Space borne (Aqua MODISAOD: 0.259e2.194) and ground based (MTP-AOD: 0.066e1.239) AODs revealed significant temporal
variability and moderate association in terms of PM10 (MODIS-AOD: 0.46; MTP-AOD: 0.56) and PM2.5
(MODIS-AOD: 0.54; MTP-AOD: 0.39). Varying association of AOD and aerosol mass loading was also
explained in terms of meteorological variables. CALIPSO altitude-orbit-cross-section profiles revealed
presence of non-spherical coarse particulates (altitude: 1.2e5.4 km) and dominance of sphericalfine
particulates (altitude: 0.1e4.2 km). Contribution of trans-boundary aerosols transportation to mass
loadings at middle IGP were recognized through lagrangian particle dispersion model, synoptic vector
wind profiles at different geopotential heights and satellite images
continuous exposure to these particles is associated with a high percentage of death from respiratory and
cardiovascular disease. In the present study, we have first time used both SEM -EDX analysis as well as
chemical analysis to understand the differences in morphology and elemental composition of aerosols sample
from a suburban clean and green area of Banaras Hindu University campus and some much polluted urban areas
of the Varanasi city situated in the eastern Indo-Gangetic plain. The analysis was done by using scanning
electron microscope (SEM) coupled with energy dispersive X-ray microanalyzer (EDX) and ionchromatography (IC). Analyses show that C, Ca, Na, S, Si, Al have dominated the sample s. The concentration
for urban areas of city were more than the pollution of suburban area and followed the trend as Na
+
> SO
4
2->
Ca
2+
> Cl
-> Mg
2+
> NO
3
-> K
+
> HCO3
+
> F
-, where as for suburban area showed the trend as Na
+
> SO
4
2->
NO3
-> Ca
2+
> Cl
-> Mg
2+
> K
+
> HCO3
+
> F
-. This shows that more polluted urban areas were dominated by
soil-dust generated due to heavy traffic movement and construction/industries. To establish differences among
sites more measurements are necessary in different meteorological conditions.
Shani Tiwari, A.K. Singh, V.K. Soni, S.D. Attri
a mixture of sulfate, dust, black carbon, and other soluble and
insoluble components. It is a challenge not only to identify
these various aerosol types, but also to assess the optical and
radiative implications of these components. In the present
study, appropriate thresholds for fine-mode fraction and
single-scattering albedo have been used to first identify the
aerosol types over IGB. Four major aerosol types may be
identified as polluted dust (PD), polluted continental (PC),
black carbon-enriched (BCE), and organic carbon-enriched
(OCE). Further, the implications of these different types of
aerosols on optical properties and radiative forcing have been
studied. The aerosol products derived from CIMEL sun/sky
radiometer measurements, deployed under Aerosol Robotic
Network program of NASA, USA were used from four different sites Karachi, Lahore, Jaipur, and Kanpur, spread over
Pakistan and Northern India. PD is the most dominant aerosol
type at Karachi and Jaipur, contributing more than 50 % of all
the aerosol types. OCE, on the other hand, contributes only
about 12–15 % at all the stations except at Kanpur where its
contribution is∼38 %. The spectral dependence of AOD was
relatively low for PD aerosol type, with the lowest AE values
(<0.5); whereas, large spectral dependence in AOD was observed for the remaining aerosol types, with the highest
AE values (>1.0). SSA was found to be the highest for OCE
(>0.9) and the lowest for BCE (<0.9) type aerosols, with drastically different spectral variability. The direct aerosol radiative forcing at the surface and in the atmosphere was found to be the maximum at Lahore among all the four stations in the
IGB
different optical and radiative properties were continuously measured at a coalfield area in Dhanbad (23° 47′N,
86° 30′E: 222 m amsl), India for thefirst time from 1st January to 31st December, 2012. Daily BC mass concentrations varied within the range of 0.84–17.0μgm
−3
with an annual average of 6.3 ± 2.7μgm
−3
. About 45% of samples of the measured days exceeded the mean level of BC indicating the high loading of soot particles over the study
region. Intra-seasonal variation in BC concentrations exhibited a strong seasonal cycle with the highest concentrations during winter (8.2 ± 2.8μgm
−3
), followed by post-monsoon (6.4 ± 2.6μgm
−3
), pre-monsoon (5.5 ±
1.9μgm
−3
) and monsoon (4.6 ± 1.7μgm
−3
). In diurnal analysis, BC showed a significant peak from 06:00 to
10:00 local time (LT) during all the seasons whereas the lowest concentrations were found during 14:00 to
17:00 LT in the late afternoon. The difference between maximum and minimum concentrations of BC was found
to be higher during winter (8.3μgm
−3
) followed by post-monsoon (4.7μgm
−3
), pre-monsoon (4.3μgm
−3
)
and monsoon (1.7μgm
−3
). An interesting feature was seen in the difference between morning and evening
peaks, it was maximum during winter (4.8μgm
−3
) followed by pre-monsoon (1.5μgm
−3
)andpost-monsoon
(1.3μgm
−3
), however, during monsoon, it was opposite i.e. ~23% lower during morning time. During day-time
and night-time variability analyses, itfluctuated largely, varying from 1% (December) to 35% (June) higher during
night-time as compared to day-time as whole mean was ~19%. Data of BC were separated as stable (b1ms
−1
)and
unstable weather conditions (N1ms
−1
), the corresponding values of BC were 6.06 and 3.75μgm
−3
respectively
which is ~38% higher during stable weather condition indicating that the major portion of BC was mainly emitted
from local sources instead of transported from remote sources. Apart from this, it was observed that the concentration of BC mass during winter was ~78% higher (8.2μgm
−3
) as compared to monsoon (4.6μgm
−3
) when the
winds were from the SE (158°) direction.
as natural particles over the Indo-Gangetic Plains (IGP), it is
important to study the characteristics of fine (PM2.5)and
inhalable particles (PM10), including their morphology, physical and chemical characteristics, etc., in Delhi during winter
2013. The mean mass concentrations of fine (PM2.5)and
inhalable (PM10) (continuous) was 117.6±79.1 and 191.0±
127.6μgm−3
, respectively, whereas the coarse mode
(PM10–2.5) particle PM mass was 73.38±28.5 μgm−3
.
During the same period, offline gravimetric monitoring of
PM2.5was conducted for morphological analysis, and its concentration was ~37 % higher compared to the continuous
measurement. Carbonaceous PM such as organic carbon (OC) and elemental carbon (EC) were analyzed on the collected filters, and their mean concentration was respectively 33.8 and 4.0μgm
−3
during the daytime, while at night it was 41.2
and 10.1μgm
−3
, respectively. The average OC/EC ratio was
8.97 and 3.96 during the day and night, respectively, indicating the formation of secondary organic aerosols during daytime. Effective carbon ratio was studied to see the effect of
aerosols on climate, and its mean value was 0.52 and 1.79
during night and day, indicating the dominance of absorbing
and scattering types of aerosols respectively into the atmosphere over the study region. Elemental analysis of individual
particles indicates that Si is the most abundant element
(~37–90 %), followed by O (oxide) and Al. Circularity and
aspect ratio was studied, which indicates that particles are not
perfectly spherical and not elongated in any direction.
Trajectory analysis indicated that in the months of February
and March, air masses appear to be transported from the
Middle Eastern part along with neighboring countries and
over Thar Desert region, while in January it was from the
northeast direction which resulted in high concentrations of
fine particles
of aerosol mass loading, optical properties, altitudinal distributions and both high and low altitude
transportation. Both space-borne passive (Aqua and Terra MODIS) and active sensor (CALIPSO-CALIOP)
based measurements were concurrently used over the selected transect (25
10
0e25
19
0
N and 82
54
0
e83
4
0E). Exceptionally high aerosol mass loading was recorded for PM10(233±58.37mgm
3) and PM2.5
(138±47.12mgm
3). Daily variations of PM2.5/PM10persist in a range of 0.25e0.97 (mean¼0.60±0.14;
n¼90) and were in accordance to computed Angstrom exponent (0.078e1.407; mean: 1.002±0.254)
explaining concurrent contribution of both PM2.5and PM10for the region. Space borne (Aqua MODISAOD: 0.259e2.194) and ground based (MTP-AOD: 0.066e1.239) AODs revealed significant temporal
variability and moderate association in terms of PM10 (MODIS-AOD: 0.46; MTP-AOD: 0.56) and PM2.5
(MODIS-AOD: 0.54; MTP-AOD: 0.39). Varying association of AOD and aerosol mass loading was also
explained in terms of meteorological variables. CALIPSO altitude-orbit-cross-section profiles revealed
presence of non-spherical coarse particulates (altitude: 1.2e5.4 km) and dominance of sphericalfine
particulates (altitude: 0.1e4.2 km). Contribution of trans-boundary aerosols transportation to mass
loadings at middle IGP were recognized through lagrangian particle dispersion model, synoptic vector
wind profiles at different geopotential heights and satellite images
continuous exposure to these particles is associated with a high percentage of death from respiratory and
cardiovascular disease. In the present study, we have first time used both SEM -EDX analysis as well as
chemical analysis to understand the differences in morphology and elemental composition of aerosols sample
from a suburban clean and green area of Banaras Hindu University campus and some much polluted urban areas
of the Varanasi city situated in the eastern Indo-Gangetic plain. The analysis was done by using scanning
electron microscope (SEM) coupled with energy dispersive X-ray microanalyzer (EDX) and ionchromatography (IC). Analyses show that C, Ca, Na, S, Si, Al have dominated the sample s. The concentration
for urban areas of city were more than the pollution of suburban area and followed the trend as Na
+
> SO
4
2->
Ca
2+
> Cl
-> Mg
2+
> NO
3
-> K
+
> HCO3
+
> F
-, where as for suburban area showed the trend as Na
+
> SO
4
2->
NO3
-> Ca
2+
> Cl
-> Mg
2+
> K
+
> HCO3
+
> F
-. This shows that more polluted urban areas were dominated by
soil-dust generated due to heavy traffic movement and construction/industries. To establish differences among
sites more measurements are necessary in different meteorological conditions.