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 TannerTom 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:• Chemical Ionization Mass Spectrometer• Based on reaction of PA radicals with I-

• Fast (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 3018Tropospheric Photochemistry II

Which PANs were measured?Example flight 7/20/2004, NYC plume

3000

2500

2000

1500

1000

500

0

PA

N, A

ltitu

de

19:207/20/2004

19:30 19:40

350

300

250

200

150

100

50

0

PP

N, P

BN

, AP

AN

, MoP

AN

, PB

zN

19:157/20/2004

19:20 19:25 19:30 19:35 19:40

dat

PAN (pptv) PPN (pptv) PBN (pptv) PBzN (pptv) APAN (pptv) MoPAN (pptv) Flt. Altitude (m)

Biomass burning plume encountered over Quebec 7/28/2004

Flight alt. const. 3000m

1600

1400

1200

1000

800

600

400

200

PA

N (

pptv

)

16:307/28/2004

16:35 16:40 16:45 16:50 16:55 17:00

150

100

50

0

PP

N, P

BN

, MoP

AN

, AP

AN

, PB

zN (pptv)

PAN PPN PBN APAN PBzN MoPAN

Flight alt. 3000m

Biomass burning plume encountered over Quebec 7/28/2004

Flight Alt. const. 3000m

1600

1400

1200

1000

800

600

400

200

PA

N (

pptv

)

16:307/28/2004

16:35 16:40 16:45 16:50 16:55 17:00

150

100

50

0

PP

N, P

BN

, MoP

AN

, AP

AN

, PB

zN (pptv)

PAN PPN PBN APAN PBzN MoPAN NOy_3

Flight alt. 3000m

PAN transport and NOx release

3500

3000

2500

2000

1500

1000

500

0

PA

N,

NO

x, N

Oy,

HN

O3

, A

ltitu

de

17:157/20/2004

17:30 17:45Time

100

80

60

40

Ozo

ne

Flight Altitude (m) PAN Ozone (ppbv) NOx (pptv) HNO3 (pptv) NOy (pptv) CH3CN (arb.)

7/20/2004 Biomass burning plume from AK and CDN FiresPAN is dominant NOY component, HNO3 washed out or lost on aerosols,

PAN decomposition maintains NOX on air mass descent

τ(PAN) ≈ 20h

3500

3000

2500

2000

1500

1000

500

0

PA

N, N

Ox,

NO

y, A

ltitu

de

19:507/21/2004

20:00 20:10Time

120

100

80

60

40

20

Ozo

ne

Flight Altitude (m) PAN Ozone (ppbv) NOx (pptv) HNO3 (pptv) NOy (pptv) Acetonitrile (arb.)

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

Biomass Burning during ICARTT

don’t miss

Joost de Gouw, A51G-05; Fri, 9:15, MCC 3018Tropospheric 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

PAN/PPN increases with biogenic HC burden More PAN further away from sources (?)

and loss: warm PBL: -Thermal loss is fastest

-PAN is lost faster than PPN (Kirchner et al., 2000)

PAN / PPN decreases (hours-days)

Upper Troposphere: -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

600

400

200

0

200150100500

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

Slope ~ 6

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?

2500

2000

1500

1000

500

PA

N (

pptv

)

35030025020015010050PPN (pptv)

20x103

151050NOy (pptv)

7/20/2004 flight

Slope~6

Slope~12

Slope~9

60

40

20

0

PP

N (pptv)

04:108/1/2004

04:20 04:30 04:40 04:50 05:00 05:10

dat

3000

2500

2000

1500

1000

500

0

600

500

400

300

200

100

PA

N (

pptv

); F

light

Alti

tude

/ 5

(m)

20

15

10

5

0

-5

Rat

io

PAN PPN Flt. Altitude PAN / PPN MVK + MACR (arbitr.)

7/31/2004 Flt, NYC Plume at NightBiogenic influence reflected in PAN/PPN ratio

PAN / PPN ratio:

Can we see the effect of different thermal loss rates?

Flight 8/10/2004 – NYC Plume at Night

1500

1000

500

0

PA

N (

pptv

), F

light

Alti

tude

(m

)

04:508/10/2004

05:00 05:10 05:20

dat

150

100

50

0

PP

N (pptv)

16

14

12

10

8

6

4

Rat

io PAN PPN PAN/PPN Flt. Altitude

Flight 8/10/2004 – NYC Plume at Night

1500

1000

500

0

PA

N (

pptv

), F

light

Alti

tude

(m

)

04:508/10/2004

05:00 05:10 05:20

dat

150

100

50

0

PP

N (pptv)

16

14

12

10

8

6

4

Rat

io PAN PPN PAN/PPN Flt. Altitude

1500

1000

500

0

PA

N (

pptv

), F

light

Alti

tude

(m

)

05:308/10/2004

05:40 05:50

dat

150

100

50

0

PP

N (pptv)

16

14

12

10

8

6

4

Rat

io

PAN PPN PAN/PPN Flt. Altitude

Flight 8/10/2004 – NYC Plume at Night

1500

1000

500

0

PA

N (

pptv

), F

light

Alti

tude

(m

)

06:108/10/2004

06:20 06:30

dat

150

100

50

0

PP

N (pptv)

16

14

12

10

8

6

4

Rat

io PAN PPN PAN/PPN Flt. Altitude

Flight 8/10/2004 – NYC Plume at Night

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