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[Journal of Geophysical Research - Atmospheres]
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Supporting Information for
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Real-time measurements of ambient aerosol in a polluted Indian city:
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Organic aerosol sources, characteristics and processing during foggy
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and non foggy time periods
Authors: A.Chakraborty1, D.Bhattu1, T. Gupta1*, S.N.Tripathi1, M. R. Canagaratna2
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Affiliations:
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1. Department of Civil Engineering and Center for Environmental Science and
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Engineering, Indian Institute of Technology Kanpur, Uttar Pradesh, India-208016.
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2. Aerodyne Research, Billerica, MA 01821, USA
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Correspondence to: Dr. Tarun Gupta (tarun@iitk.ac.in); Dr. S.N.Tripathi (snt@iitk.ac.in)
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Text. S1
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Figure: S1-S13
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Table: S1
S1
Study location
& season
Type of AMS
Paris,Winter 2010
HR-ToF-AMS
Hong Kong,
Winter 2012
HR-ToF-AMS
Tokyo, Winter
2004
Q-AMS
Beijing, Winter
2011-12
ACSM
PRD China,
Winter, 2009
HR-ToF-AMS
Species conc. & relative
contributions
(µg/m3 & %)
Org = 5.50 (33%),
NO3 = 4.50 (28%)
NH4 = 2.00 (13%)
SO4 = 2.50 (15 %),
Cl = 0.15 (1%)
Total NR-PM1 = 14.65
Org = 5.10 (35%),
SO4 = 6.20 (42%),
NO3 = 1.60 (11%),
NH4 = 1.60 (11%),
Cl = 0.13 (1%)
Total NR-PM1 = 14.63
Org = 5.80 (44%),
SO4 = 1.70 (13%),
NO3 = 2.80 (21%),
NH4 = 2.30 (18%),
Cl = 0.50 (4%)
Total NR-PM1 = 13.10
Org = 34.80(52%),
SO4 = 9.40 (14%),
NO3 = 10.70 (16%)
NH4 = 8.70 (13%),
Cl = 3.40 (05%)
Total NR-PM1 = 66.80
Org = 17.70 (40%),
SO4 = 10.90 (25%),
NO3 = 4.45 (10%)
NH4 = 4.50 (10.20%),
Cl = 0.70 (1.60%)
Total NR-PM1 = 44.50
Organics
component
HOA
BBOA
OOA2-BBOA
OOA
COA
Crippa et
al., 2013
LV-OOA =
19%
SV-OOA =
28%
HOA = 29%
BBOA = 24%
Li et al.,
2014
Takegawa
et al.,
2006.
HOA = 17%
COA = 19%
CCOA = 33%
COA = 31%
*CCOA =
Coal
combustion
OA
LV-OOA =
55%
SV-OOA =
26%
COA = 12%
HOA = 07%
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Table S1: Comparison with other winter season AMS studies especially in polluted
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megacities.
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Reference
Sun et al.,
2013
He et al,
2011
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Figure: S1 – S14
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Fig.S1. LWC, RH and T time series (30 min average) for fog events.
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Fig.S2. SMPS VS AMS mass comparison. SMPS volume converted to mass conc. using
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mass weighted densities of 1.43 (P1) and 1.47 g/cc (P2) as calculated from aerosol
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composition.
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Fig.S3. f44 vs f43 triangle plot for FP and NFP and HR PMF factors. More oxidized/aged
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factors occupies top left position while less oxidized primary factors occupies bottom
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right positions.
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Fig.S4A and 4B Size resolved mass fractions of aerosol species for P1 (Fig. 4A) and P2
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(Fig. 4B). Lower size range is mostly dominated by organics.
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Fig.S5. Diurnal variations of different aerosol species during FP and NFP.
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S5
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Fig.S6. NH4+ measured vs. NH4+ predicted for both the periods. Overall, FP aerosols
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were more neutralized than NFP night aerosols.
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Text S1.
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Choosing HR PMF solution:
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Fig.S5 shows the key diagnostics for HR-PMF solution. We performed HR PMF analysis
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with 1-10 factors and fpeak values ranging from -5 to +5 to get about 3% change (Zhang
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et al., 2011) over the minimum Q/Qexp value in a particular factor. We chose 6F solution
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that consists of 3 OOA factors, including one aged Biomass burning factor, 2 primary
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BBOA factor and one HOA factor and have a Q/Qexp value of 3.15. Beyond 6F solution,
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there is a little change in Q/Qexp value which means most of the data variability can be
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explained by 6 factors. 5F solution also looked good, but residuals at m/z 60, 73, 29 are
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much higher as compared to 6F, in 6F solution single OOA factor from 5F solution is
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resolved into 2 different OOA factors with very different O/C ratios, factor profile and
S6
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time series along with a substantial decrease in m/z 60, 73, 29 residuals. In 7F solution an
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additional OOA factor appears without any appreciable reduction in residuals or Q/Qexp
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value, this factor is most likely a splitting of OOA-1 factor. A higher number of factors
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beyond 7 only resulted in more splitting with identical factor profiles without providing
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any new information, so 6F solution was chosen. We choose fpeak 0 because of local
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minima in Q/Qexp is occurring here and choosing other fpeak values were not improving
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the correlation with external tracers.
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Fig S7. HR PMF Diagnostics plot
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Fig S8A and B: HR PMF factors vs. external tracers’ time series for P1 (Fig. 8A) and P2
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(Fig. 8B), respectively. Black carbon (BC) measurement (5 min average) was only
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available during NFP.
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Fig. S9: Contributions of different HR-PMF factors to the total OA. Huge increase in
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aged biomass burning OA can be seen from P1 to P2.
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Fig .S10 Back Trajectory heights. Left panel is for P1 and right one is for P2. These
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heights indicates that the sampling site is mostly influenced by surface emissions during
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winter.
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Fig. S11: Relationship of RH and O/C. Good correlation during P2_FP indicates possible
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aqueous processing.
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Fig S12. OA composition variation within P2. During actual fog events OOA
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contribution actually increased despite fog scavenging indicating its production as well.
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Fig S13. VK diagram with different POA:OOA ratios. POA = HOA+BBOA1,2, OOA=
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OOA1,2+OOA3-BBOA. Inspite of same POA:OOA ratios the slope difrrences still
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remains indicating that different chemical processes for OA evolution during P1 and P2.
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