Transcript Fast time resolution airborne measurements of PANs during the New England Air Quality Study 2004 intensive. Frank Flocke, Aaron Swanson, Jim Roberts, Greg Huey,

Fast time resolution airborne
measurements of PANs during the
New England Air Quality Study
2004 intensive.
Frank Flocke, Aaron Swanson, Jim Roberts, Greg Huey, David Tanner
Tom Ryerson, Andy Neuman,
John Holloway,
Joost deGouw, Carsten Warneke
Elliot Atlas, Stephen Donnelly, Sue Schauffler, Verity Stroud
Thanks to: NOAA AOC, Paul Stock (DLR)
New PAN-CIGAR instrument:
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Chemical Ionization Mass Spectrometer
Based on reaction of PA radicals with IFast (time resolution 0.25 – 2 seconds)
Sensitive (10-60 cts/pptv on background of
250 cts or less)
Very selective
Autonomous
Eight different PAN species measured during
ICARTT 2004
don’t miss the PAN-CIGAR Instrument talk:
Swanson et al., A42B-04; Thu, 11:20; MCC 3018
Tropospheric Photochemistry II
Which PANs were measured?
Example flight 7/20/2004, NYC plume
3000
2500
PAN, Altitude
2000
350
300
250
200
1500
150
1000
100
500
0
50
dat
19:15
7/20/2004
19:20
19:25
19:30
19:35
19:40
0
19:20
7/20/2004
19:30
19:40
PPN, PBN, APAN, MoPAN, PBzN
PAN (pptv)
PPN (pptv)
PBN (pptv)
PBzN (pptv)
APAN (pptv)
MoPAN (pptv)
Flt. Altitude (m)
Biomass burning plume encountered over Quebec 7/28/2004
PAN
PPN
PBN
APAN
PBzN
MoPAN
1600
1400
150
PAN (pptv)
1000
Flight alt. const. 3000m
Flight alt. 3000m
100
800
600
50
400
200
0
16:30
7/28/2004
16:35
16:40
16:45
16:50
16:55
17:00
PPN, PBN, MoPAN, APAN, PBzN (pptv)
1200
Biomass burning plume encountered over Quebec 7/28/2004
PAN
PPN
PBN
APAN
PBzN
MoPAN
NOy_3
1600
1400
150
PAN (pptv)
Flight Alt. const. 3000m
Flight alt. 3000m
1000
100
800
600
50
400
200
0
16:30
7/28/2004
16:35
16:40
16:45
16:50
16:55
17:00
PPN, PBN, MoPAN, APAN, PBzN (pptv)
1200
PAN transport and NOx release
7/20/2004 Biomass burning plume from AK and CDN Fires
PAN is dominant NOY component, HNO3 washed out or lost on aerosols,
PAN decomposition maintains NOX on air mass descent
3500
PAN, NOx, NOy, HNO3, Altitude
3000
2500
Flight Altitude (m)
PAN
Ozone (ppbv)
NOx (pptv)
HNO3 (pptv)
NOy (pptv)
CH3CN (arb.)
Ozone
τ(PAN) ≈ 20h
100
80
2000
1500
60
1000
40
500
0
17:15
7/20/2004
17:30
Time
17:45
7/21/2004 Same biomass burning plume from AK and CDN Fires
encountered again over Cape Cod one day later
Some processing has occurred (HNO3 formation),
still PAN decomposition maintains NOX on air mass descent
τ(PAN) ≈ 18h
PAN, NOx, NOy, Altitude
3000
2500
Flight Altitude (m)
PAN
Ozone (ppbv)
NOx (pptv)
HNO3 (pptv)
NOy (pptv)
Acetonitrile (arb.)
2000
120
100
80
1500
60
1000
40
500
20
0
19:50
7/21/2004
20:00 Time
20:10
Ozone
3500
Biomass Burning during ICARTT
don’t miss
Joost de Gouw, A51G-05; Fri, 9:15, MCC 3018
Tropospheric Photochemistry VI
PAN / PPN ratio
What controls the PAN / PPN ratio:
Production:
-PAN / PPN ratio upon formation depends on
availability of source VOC
-Alkanes/Alkenes make PAN and PPN (ratio?)
-Isoprene and Terpenes make just PAN
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PAN/PPN increases with biogenic HC burden
More PAN further away from sources (?)
and loss:
warm PBL:
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Upper Troposphere:
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-Thermal loss is fastest
-PAN is lost faster than PPN (Kirchner et al.,
2000)
PAN / PPN decreases (hours-days)
-Photolysis dominates
-PPN photolysis slightly faster than PAN
(Harwood et al., 2003)
PAN / PPN increases very slowly (weeks)
PAN / PPN ratio:
Is there an “anthropogenic” PAN/PPN ratio?
PAN/PPN during TRACE-P
1000
800
Slope ~ 6
600
400
pFW_PAN_pptv
PAN_100_160
PAN_160_200
PAN_200_240
PAN_US
Fit_100_160 slope = 5.6
Fit_160_200 slope = 6.1
Fit_200_240 slope = 9.0
Fit_US
slope = 6.2
200
0
0
50
100
150
200
Similar slopes of PAN / PPN were obtained in Houston
(TexAQS 2000),
during TOPSE (Spring 2000) and in/over other urban areas
PAN / PPN ratio:
and in New England?
7/20/2004 flight
Slope~12
2500
Slope~9
Slope~6
PAN (pptv)
2000
1500
1000
500
0
50
100
5
10
15
NOy (pptv)
150
200
250
PPN (pptv)
300
3
20x10
350
7/31/2004 Flt, NYC Plume at Night
Biogenic influence reflected in PAN/PPN ratio
20
Ratio
600
PAN
PPN
Flt. Altitude
PAN / PPN
MVK + MACR (arbitr.)
60
3000
500
2500
400
2000 10
40
300
200
PPN (pptv)
PAN (pptv); Flight Altitude / 5 (m)
15
1500
5
1000
20
0
100
500
0 -5
04:10
8/1/2004
0
04:20
04:30
04:40
04:50
05:00
05:10
PAN / PPN ratio:
Can we see the effect of different thermal loss rates?
Ratio
Flight 8/10/2004 – NYC Plume at Night
PAN
PPN
PAN/PPN
Flt. Altitude
1500
150
PPN (pptv)
PAN (pptv), Flight Altitude (m)
16
14
12
1000
100
10
8
500
50
6
0
4
04:50
8/10/2004
05:00
0
05:10
05:20
Ratio
Flight 8/10/2004 – NYC Plume at Night
PAN
PPN
PAN/PPN
Flt. Altitude
1500
150
PPN (pptv)
PAN (pptv), Flight Altitude (m)
16
14
12
1000
100
10
8
500
50
6
0
4
04:50
8/10/2004
05:00
0
05:10
05:20
Flight 8/10/2004 – NYC Plume at Night
PAN
PPN
PAN/PPN
Flt. Altitude
1500
150
14
Ratio
12
1000
100
10
8
500
50
6
0
4
05:30
8/10/2004
0
05:40
05:50
PPN (pptv)
PAN (pptv), Flight Altitude (m)
16
Ratio
Flight 8/10/2004 – NYC Plume at Night
PAN
PPN
PAN/PPN
Flt. Altitude
PAN (pptv), Flight Altitude (m)
16
1500
150
14
12
1000
100
10
500
8
50
6
0
4
0
06:10
8/10/2004
06:20
06:30
SUMMARY
• First fast time resolution airborne measurements of
PAN
• We observed 8 different PANs including
first observations of MoPAN, PPeN (and PBzN)
• Elevated APAN and MoPAN in biomass burning
plumes
• One can learn a lot about photochemical history of
air masses by just measuring PAN and PPN
accurately
• We can do that now at 2 Hz or better
• Biomass burning plumes show distinct PAN/PPN
ratio which appears preserved over several
days