Application of the PTM-MCM to the TORCH-1

campaign

Steve Utembe, Mike Jenkin and David JohnsonEPSR GroupDepartment of Environmental Science and Technology

Studies using the PTM

• Chemical development of air parcels arriving at Writtle site investigated, at six-hourly resolution for the entire campaign

• 156 96-hours back trajectories obtained from NOAA

• Chemical processing using CRI mechanism

• Additional analysis of selected trajectories using MCM v3.1

Brief description of the PTM

4-day back trajectory

VOC and NOX

sunlight

chemistry and transport

emissions

calculate ozone along pre-selected trajectories

over Europe

well-mixedboundarylayer box

Emissions

• UK anthropogenic emissions based on NAEI.

• Anthropogenic emissions outside UK based on EMEP.

• Biogenic VOC emissions based on Simpson (1995).

• Idealised seasonal, weekly and diurnal variations applied.

• NMVOC emissions speciation based on NAEI for ca. 70% of total. Remaining 30% assigned to surrogates for which chemistry treated.

Emissions speciation: 124 anthropogenic NMVOC

0.00

0.02

0.04

0.06

0.08

0.10

0.12

C2

H6

NC

4H

10

NC

5H

12

NE

OP

M2

PE

M2

2C

4

NC

7H

16

M3

HE

X

NC

9H

20

NC

11

H2

4

CH

EX

C3

H6

CB

UT

2E

NE

ME

PR

OP

EN

E

CP

EN

T2

EN

E

ME

2B

UT

1E

NE

ME

2B

UT

2E

NE

CH

EX

2E

NE

C4

H6

AP

INE

NE

HC

HO

C2

H5

CH

O

IPR

CH

O

GL

YO

X

CH

3C

OC

H3

MP

RK

DIE

K

HE

X3

ON

E

MT

BK

CH

3O

H

NP

RO

PO

L

0.00

0.02

0.04

0.06

0.08

NB

UT

OL

IBU

TO

L

PE

CO

H

IPE

AO

H

IPE

CO

H

CY

HE

XO

L

PR

OP

GL

Y

DIE

TE

TH

ER

MT

BE

DM

M

MO

2E

OL

EO

X2

EO

L

BO

X2

PR

OL

CH

3C

O2

H

CH

3O

CH

O

ET

HA

CE

T

IPR

OA

CE

T

SB

UT

AC

ET

BE

NZ

EN

E

OX

YL

PX

YL

TM

12

3B

TM

13

5B

ME

TH

TO

L

PB

EN

Z

DIM

E3

5E

B

ST

YR

EN

E

CH

3C

L

CH

CL

3

CD

ICL

ET

H

TR

ICL

ET

H

alkanes alkenes carbonyls

alcohols ethers esters aromaticsacids chloro-carbons

fract

ion o

f to

tal

butane ethanol

toluene

Ozone: observed vs calculated

0

20

40

60

80

100

120

140

160

26/07 31/07 05/08 10/08 15/08 20/08 25/08

Co

nce

ntr

atio

n (

pp

b)

Observed ozone

Simulated Ozone

Ozone observed vs calculated : sensitivity to trajectory height

0

20

40

60

80

100

120

140

160

26/07 31/07 05/08 10/08 15/08 20/08 25/08

Co

nce

ntr

atio

n (

pp

b)

Observed ozoneSimulated OzoneSimulated ozone (500m traj)

Emitted aromatic hydrocarbon: toluene

0

500

1000

1500

2000

2500

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

co

nc

en

tra

tio

n (

pp

t)

simulatedobserved

toluene

Emitted aromatic hydrocarbons

0

200

400

600

800

1000

1200

1400

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

co

nc

en

tra

tio

n (

pp

t) simulatedobserved

benzene

0

100

200

300

400

500

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

co

nc

en

tra

tio

n (

pp

t)

simulatedobserved

o-xylene

0

500

1000

1500

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt)

simulatedobserved

m+p-xylene

0

200

400

600

800

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt)

simulatedobserved

ethylbenzene

Emitted alkyne: acetylene

0

500

1000

1500

2000

2500

3000

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

co

nc

en

tra

tio

n (

pp

t) simulatedobserved

acetylene

Emitted alkanes

0

2000

4000

6000

8000

10000

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt)

simulatedobserved

ethane

0

2000

4000

6000

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt)

simulatedobserved

butane

0

500

1000

1500

2000

2500

3000

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt)

simulatedobserved

i-butane

0

500

1000

1500

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt)

simulatedobserved

octane

Emitted cycloalkane: cyclohexane

(used as a surrogate for all emitted cycloalkanes)

0

500

1000

1500

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

co

nc

en

tra

tio

n (

pp

t)

simulatedobserved

cyclohexane

simulated (adjusted)

Emitted alkenes and dienes

0

500

1000

1500

2000

2500

3000

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

co

nc

en

tra

tio

n (

pp

t) simulatedobserved

ethene

0

20

40

60

80

100

120

140

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt) simulated

observed

trans-2-butene

0

20

40

60

80

100

120

140

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt) simulated

observed

trans-2-pentene

0

50

100

150

200

250

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt)

simulatedobserved

1,3-butadiene

Emitted biogenic hydrocarbon: isoprene

0

200

400

600

800

1000

1200

1400

25/07 30/07 04/08 09/08 14/08 19/08 24/08 29/08

Co

nce

ntr

atio

n (

pp

t) Observed isoprene

Simulated Isoprene

Mean hydrocarbon concentrations

1

10

100

1000

10000

1 10 100 1000 10000observed concentration (ppt)

sim

ulat

ed c

once

ntra

tion

(ppt

)

aromaticsalkynesalkenesdienesalkanes1:1 line2:1 line1:2 line

isoprene

i-butene

cis -2-pentene

cyclohexane

octanehexane

TORCH-1 campaign:mean hydrocarbon concentrations

Aldehyde with primary and secondary sources: HCHO

0

2000

4000

6000

8000

10000

7/27/2003 0:00 8/1/2003 0:00 8/6/2003 0:00 8/11/2003 0:00 8/16/2003 0:00 8/21/2003 0:00

con

cen

trat

ion

(p

pt) Simulated

Observed

HCHO

preliminary HCHO measurements made by UEA

Simulated aldehyde product distributions on 3 example trajectories

HCHO

CH3CHO

C2H5CHO

NBUTANAL

IBUTANAL

NPENTANAL

0.01

0.1

1

C

B

A

Increasing air mass age

Spe

cies

con

cent

ratio

n / p

pb

(N.B. we have simulated concentration data on 1257 carbonyl compounds)

Simulated ketone product distributions on 3 example trajectories

ACETONE

BUTANONE

2PENTANONE

3PENTANONE

3METHYL-2-BUTANONE

2HEXANONE

3HEXANONE

4METHYL-2-PENTANONE

0.01

0.1

1

C

B

A

Increasing air mass age

Ket

one

conc

entr

atio

n / p

pb

Concentrations of selected carbonyl products from aromatics

Concentrations of selected carbonyl products from biogenics

Organic nitrates and relationship to precursor peroxy radicals

Ozone and organic nitrates are both produced from reaction of peroxy radicals with NO

RO2 + NO [ROONO]* RO. + NO2(R1)

+ M RONO2 (R2)

Correlation between the concentration of the two

[RO2]i [RONO2]i/i

where i = k1/k2

Comparison of relative concentrations of RO2 radicals produced from reactions of OH with

alkanes and alkenes (O’Brien et al. 1995)

0

0.2

0.4

0.6

0.8

1

1.2

Rela

tive [

RO

2]

O'Brien et al 1995

Alkyl peroxy RO2’s

-hydroxy

24 hours chemical processing

Concentrations at end of day 5 for a series of alkyl and -hydroxyalkyl peroxy radicals calculated with the

MCM/PTM show similar distribution of peroxy radicals inferred from the organic nitrate observations of O'Brien

et al.

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Rela

tive [

RO

2] Trajectory B

Trajectory C

-hydroxy

5 days chemical processing

Alkyl peroxy RO2’s

Concentration distribution of C1-C5 alkyl nitrates in MCM3.1

METHYL NO3

ETHYL NO3

1-PROPYL NO3

2-PROPYL NO3

1-BUTYL NO3

2-BUTYL NO3

2-METHYL-1-PROPYL NO3

2-METHYL-2-PROPYL NO3

1-PENTYL NO3

2-PENTYL NO3

3-PENTYL NO3

2-METHYL-1-BUTYL NO3

2-METHYL-3-BUTYL NO3

2-METHYL-2-BUTYL NO3

2,2-DIMETHYL-1-PROPYL NO

0.02

0.04

0.06

C

B

A

Increasing air mass age

Alk

yl n

itrat

e co

ncen

trat

ion

/ ppb

v

Concentration distribution of C2-C4 -hydroxy alkyl nitrates in MCM3.1

1-HYDROXY-2-ETHYL NO3

1-HYDROXY-2-PROPYL NO3

2-HYDROXY-1-PROPYL NO3

1-HYDROXY-2-BUTYL NO3

2-HYDROXY-1-BUTYL NO3

2-HYDROXY-3-BUTYL NO3

2-METHYL-2HYDROXY-1-PROP

2-METHYL-1-HYDROXY-2-PRO

0.000

0.002

0.004

0.006

0.008

0.010

C

B

A

Increasing air mass age

Alk

yl n

itrat

e co

ncen

trat

ion

/ ppb

Identifying top contributors to total carbonyl distribution in MCM v3.1

There are 1257 carbonyls in MCM v3.1(!)

What are the dominant carbonyls in air masses of different degrees of photochemical processing?

Top contributors to 90% of total carbonyl concentration

0

5

10

15

20

25

30

35

40

CH

3CO

CH

3

HC

HO

ME

K

CH

3CH

O

CY

6TR

ION

CY

HE

XO

NE

GLY

OX

C2H

5CH

O

DIE

K

HO

CH

2CH

O

MIP

K

NC

4MD

CO

2H

MG

LYO

X

CO

24C

5

CO

2C5O

H

% R

elat

ive

abu

nd

ance

0

5

10

15

20

25

30

35

40

HC

HO

CH

3CO

CH

3

CH

3CH

O

ME

K

C2H

5CH

O

CY

HE

XO

NE

GLY

OX

NO

PIN

ON

E

MG

LYO

X

HO

CH

2CH

O

C9D

C

CO

2C5O

H

C96

NO

3

DIE

K

CY

6TR

ION

MIP

K

NC

4MD

CO

2H

CY

C61

3DIO

N

C61

4CO

HO

1CO

4C6

HO

3CO

6C8

NO

PIN

AN

O3

C3H

7CH

O

PIN

AL

HC

OC

H2C

HO

CO

36C

8

HO

2CO

5C6

% R

elat

ive

abu

nd

ance

0

5

10

15

20

25

30

35

40

45

CH

3CO

CH

3

HC

HO

CH

3CH

O

ME

K

GLY

OX

CY

HE

XO

NE

C2H

5CH

O

C9D

C

NO

PIN

ON

E

HO

CH

2CH

O

MG

LYO

X

C96

NO

3

CY

6TR

ION

CO

2C5O

H

DIE

K

NO

PIN

AN

O3

C61

4CO

MIP

K

NC

4MD

CO

2H

CY

C61

3DIO

N

HC

OC

H2C

HO

C9D

CN

O3

PIN

ON

IC

% R

elat

ive

abu

nd

ance

Least photochemically

processed

Intermediate

Most photochemically

processed

HCHO

CH3COCH3

CH3COCH3

HCHO

MEK

CH3CHO

MEK

CH3CHO

Concluding remarks• Simulation of TORCH-1 campaign using PTM-CRI has allowed

emitted VOC speciation to be tested. Simulated and observed hydrocarbon concentrations were generally well correlated.

• Simulated concentrations of 6 aromatics, acetylene, 1,3-butadiene and intermediate alkanes were in very good agreement with observations.

• Simulated concentrations of alkenes and small alkanes tended to be slightly lower than observations.

• Simulated concentrations of larger alkanes were generally greater than those observed: this mainly due to ‘surrogate’ contributions.

• MCM allows study of distributions of concentrations of various classes of VOCs