1

Institute for Reference Materials and Measurements (IRMM)Geel, Belgium

http://www.irmm.jrc.behttp://www.jrc.ec.europa.eu

High precision CO2 isotope analyses of air samples from the free tropical troposphere and upper troposphere-

lowermost stratosphere region:The CARIBIC project

S.S. Assonov 1, 2, C.A.M. Brenninkmeijer 2, T. Schuck 2, A. Zahn 3, P.Taylor 1

1- Joint Research Centre of European Commission (EC), Institute for Reference Materials and Measurements (IRMM), Geel, Belgium;

2- Max Planck Institute for Chemistry, Mainz, Germany;3- IMK, KIT Karlsruhe, Germany

15th WMO/IAEA Meeting of Experts on Carbon Dioxide and Related TracerMeasurement Techniques,

September 7–10, 2009, Jena, Germany

2

Outline

We present:

1. Data overview and data de-trending. Use of stratospheric tracers to separate LMS air masses

2. CO2 isotope signals in the UT/LMS mixing region

3. CO2 isotope signals in the free troposphere and upper troposphere

4. Effect of global tropospheric circulation

5. Summary

We acknowledge:• JRC-IRMM colleagues helped us during CARIBIC-2 measurements

• I.Levin and A.Jordan helped us with GHG calibrations

• Discussions with W. Brand, T.S. Rhee and P. Robuch

• The great effort by NOAA and INSTAAR to obtain the data and make them available, in particular J.White, P.Tans, B.Vaughn and Ed Dlugokencky (N2O data)

• W. Brand kindly measured 28 air samples of CARIBIC-2 in 2009

• T. Röckmann played an important role in obtaining the CO2 extractions for CARIBIC-1.

3

What is CARIBIC?www.caribic-atmospheric.com

Inlet system

Container position

Long-existing team of 11 institutions.

Analyzed: CO2, N2O, CH4, SF6, NMHC, O3, CO, water, halogenated compounds, aerosols, meteorological data etc.

• Lufthansa A340-600 - new high capacity, long range airplane.

• Automated observatory cruising at ~11 km altitude. • Regular flights from Germany to remote destinations. • Cost-effective way to study the atmosphere.

CARIBIC-1: 1998-2002 CARIBIC-2: started in 2004

4

CARIBIC-2 flight routes: samples analyzed for CO2 isotopes

5

CARIBIC-1,~ 350 samples

CARIBIC-2,~ 500 samples

9901

01

9904

01

9907

01

9910

01

0001

01

0004

01

0007

01

0010

01

0101

01

0104

01

0107

01

0110

01

0201

01

0204

01

0207

01

-30

0

30

60

0704

01

0707

01

0710

01

0801

01

0804

01

0807

01

0810

01

0901

01

0904

01

-30

0

30

60

Flight directions: India+Sri Lanka South Africa Caribbean region

Lat

itu

de

Date, YYMMDD

Flight directions:PhilippinesNorth AmericaIndiaSouth Africa

Lat

itu

de

Date, YYMMDD

Mostly NH, latitudes 14 to 55 oN

1. Geographical distribution of samplesanalyzed for CO2 isotopes

6

0 100 200 300 400 500 600

6.0

6.5

7.0

7.5

0 100 200 300 400 500 600

380

385

390

395

400

280

290

300

310

320

1500

1550

1600

1650

1700

1750

1800

1850

1900

SF

6, pp

t

O3, ppb

CO

2, pp

mO3, ppb

N2O

, pp

b CH

4, pp

b

(Data not de-trended).

All GHG signals demonstrate large variability for the free troposphere (FT) and upper troposphere (UT) air masses (ozone typically below 100 ppb) and a mixing trend towards LMS air masses (high ozone).

1. GHG data for CARIBIC-2, April 2007 to March 2009

7

Linear fits for annual means of CO2 and N2O for some NOAA stations and the d13C(CO2) trend.

Annual increase rates (linear fit) determined based on the NOAA stations.Compound Stations Data source (monthly means) Years Annual increase (linear fit)

CO2 MLO, KUM, MID NOAA web-site 1999-2007 2.04 ppm/y

d13C(CO2) MLO, KUM, MID NOAA web site 1999-2007 -0.032 ‰/y

N2O MLO, KUM, IZO, AZR Obtained from E.Dlugogencky

1998-2008 0.76 ppb/y

1998 2000 2002 2004 2006 2008365

370

375

380

385

2.60 2.65 2.70-8.4

-8.2

-8.0

1998 2000 2002 2004 2006 2008

314

316

318

320

322

1998 2000 2002 2004 2006 2008-1.0

-0.5

0.0

0.5

2.60 2.65 2.70-0.05

0.00

0.05

1998 2000 2002 2004 2006 2008-1.0

-0.5

0.0

0.5

year

KUM MLO MID linear fit

CO

2, ppm y = 2.043x - 3717.44

KUM MLO linear fit

δ13C

(CO

2), ‰

1000/CO2, ppm-1

y = 2220.021x - 14.11

y = 0.76x - 1203.01

N2O

, pp

b

KUM MLO IZO AZR linear fit

year

year

Res

idu

als,

ppm

Res

idu

als,

‰

1000/CO2, ppm-1

Res

idu

als,

ppb

year

1. Data de-trending

8

The scatter includes seasonal variations and some errors in de-trending.

319.8 320.0 320.2 320.4 320.6 320.8 321.0 321.2 321.40

5

10

15

20

25

30

Median =320.711 St.Dev.=0.26

Cou

nts

N2O, ppb

KUM

319.8 320.0 320.2 320.4 320.6 320.8 321.0 321.2 321.40

5

10

15

20

25

30

Cou

nts

N2O, ppb

MLO Median =320.761 St.Dev.=0.24

319.8 320.0 320.2 320.4 320.6 320.8 321.0 321.2 321.40

5

10

15

20

25

30

Cou

nts

N2O, ppb

IZOMedian = 320.871 St.Dev. = 0.27

319.8 320.0 320.2 320.4 320.6 320.8 321.0 321.2 321.40

5

10

15

20

25

30

Median = 320.661 St.Dev.= 0.33

Cou

nts

N2O, ppb

AZR

1. N2O data of NOAA stations, de-trended for 1/1/2007 (monthly means, 1998-

2008)

9

325 320 315 310 305 300 29510

20

30

40

50

60

-100

0

100

200

300

400

5000 50 100 150 200

325

320

315

310

305

300

295

290

0 50 100 150 200 290 300 310 3206000

8000

10000

12000

0 50 100 150 200

PV < 2.0PVU PV > 2.0PVU

Latit

ude

de-trended N2O, ppb

PV < 2.0PVU PV > 2.0PVU

O3 e

xces

s vs

. che

m. t

ropo

paus

e

CO, ppb

de-t

rend

ed N

2O, p

pb

Alti

tude

, m

de-trended N2O, ppb

CO, ppb

Ozone or N2O? Tracer’s distribution

1. Tropospheric and stratospheric tracers

10

0.01

0.5

2

10

30

50

70

90

98

99.5

294 296 298 300 302 304 306 308 310 312 314 316 318 320 322 324

294 296 298 300 302 304 306 308 310 312 314 316 318 320 322 3240

10

20

30

40

50

60

70

80

90 Corrected for N2O increase, for 1/1/2007

Cou

nts

Bin

CARIBIC-2, de-trended data

Cum

ulat

ive

Cou

nts

CARIBIC-2, de-trended N2O data :

• The tailing is due to UT/LMS mixing; • The cut-off to separate LMS samples is taken at 320.0 ppm.

CARIBIC-1: similar distribution but higher increase rate applied, 0.9 ppb/y.

1E-30.01

0.52

10

305070

90

9899.5

99.99292 294 296 298 300 302 304 306 308 310 312 314 316 318 320 322 324

292 294 296 298 300 302 304 306 308 310 312 314 316 318 320 322 3240

10

20

30

40

50

60 N2Odetrented

Cou

nts

Bin

CARIBIC-1 de-trended data

Cum

ulat

ive

Cou

nts

1. Use of N2O as a filter to separate UT and LMS air masses

11

Conclusions - Part 1

• All GHG signals demonstrate large variability for UT and FT air (ozone typically below 100 ppb) and a mixing trend towards LMS air (high ozone). Latitudes 35 to 55 oN are affected by LMS air

• De-trending is based on the data of stations in NH tropics

• N2O – best stratospheric tracer to separate LMS air masses for CO2

analyses

12

• Uplifted equatorial and tropical air is transported pole-wards and then descends at pole region and also at mid-latitudes;

• Some age distribution of stratospheric air;

• The intermediate reservoir, LMS, has a complex ventilation regime. Isentropic mixing and double tropopauses are examples of this complexity;

• CO and ozone are often in use as contrast tracers;

• Specific L-shape mixing plot (green dots);

• The UT/LMS trends observed by CARIBIC are governed by stratospheric circulation and UT/LMS mixing.

20 40 60 80 1000

100

200

300

400

500 January 2000

TPchemical

UnperturbedLowermost

Stratosphere

Troposphere

Ozo

ne (p

pbv)

Carbon Monoxide (ppbv)

0.5

1.0

1.5

2.0

2.5

3.0

92 ppbv

MixingLayer

Circa A

ltitude above TP

chemical (km

)

2. Stratospheric circulation and UT/LMS region

13

0 200 400

382

384

386

310

315

320

322

320

318

316

314

312

0.00 0.25 0.50 0.75

322

320

318

316

314

312

-8.4 -8.3 -8.2381 382 383 384 385 386

-8.4

-8.3

-8.2

381 382 383 384 385 3860.00

0.25

0.50

0.75

0 25 50 75 100 125 150

322

320

318

316

314

3123

4

5

67 8

9 101112

13

14

1516 17

18

19 20 21

2223

24

25

26

27

345

6

78

910

11

12

13

14

1516

1718

19

20

21

2223

24

25 26

27

3 45

6

78

910

11

12

13

14

1516

1718

19

20

21

2223

24

25 26

273

4

5

678

9101112 13

14

151617 18

192021

2223

24

2526

27

345

678

9101112

13

14

151617 18

192021

2223

24

252627

14

1516

1718

19

20

21

2223

2526

27

CO

2, p

pm

O3, ppb

N2O

, pp

b

δ18O(CO2), ‰

N2O

, pp

b

flight 218-219 FRA-Denver-FRA, 17-18 Dec. 2007, latitudes 41 to 63oN

δ13C(CO2), ‰

N2O

, pp

b

δ13

C(C

O2),

‰

CO2, ppm

δ18O

(CO

2), ‰

CO2, ppm

N2O

, pp

b

CO, ppb

L-shape mixing plot of O3 (and N2O) vs. CO is visible for CO2 isotopes.

2. UT/LMS mixing trends for a particular flight

14

290 300 310 320-1.0

-0.5

0.0

0.5

1.0-8.6

-8.4

-8.2

-8.0

375

380

385

390

Latitudes < 35o N Latitudes > 35o N

δ18O

(CO

2), ‰

N2O, ppb

δ13C

(CO

2), ‰

CO

2, pp

m• Large variability in FT and UT air (green);

• Mixing trends towards a stratospheric component (lower N2O);

• The same features for CARIBIC-1.

The trend is based on data of stratospheric CO2(Lämmerzahl et al, 2002; Boering et al, 2004)

• Increase of δ18O(CO2)

2. UT/LMS mixing trends, CARIBIC-2

15

Conclusions, Part 2

• UT/LMS mixing is an important reason for the signal variability. CO2isotope data reflect air mixing in the UT/LMS region;

• N2O works well as stratospheric tracer; it can be used to filter out the LMS data;

• d18O(CO2) is a tracer principally different from other long lived chemical tracers (CO2, N2O, SF6). The d18O(CO2) distribution in UT/LMS can be used as independent tracer to validate descriptions of global transport and UT/LMS mixing in models.

16

(Data de-trended for 1/1/2007)

-40 -20 0 20 40 60375

380

385

390

-40 -20 0 20 40 60

320

321

322

323

-40 0 40-8.6

-8.4

-8.2

-8.0

-40 -20 0 20 40 60

-1.0

-0.5

0.0

0.5

1.0

CO

2, pp

m

Latitude

Mean & 1St.Dev. of 10-degree bins

N2O

, pp

b

Latitude

δ13C

(CO

2), ‰

Latitude

CARIBIC-1 CARIBIC-2

δ18O

(CO

2), ‰

Latitude

3. CO2 signals in the free troposphere and upper troposphere, latitudinal distribution

17

(The trend lines are given for KUM).

-8.4

-8.2

-8.0

-7.8

1/1/

1999

4/1/

1999

7/1/

1999

10/1

/199

9

1/1/

2000

4/1/

2000

7/1/

2000

10/1

/200

0

1/1/

2001

4/1/

2001

7/1/

2001

10/1

/200

1

1/1/

2002

4/1/

2002

7/1/

2002

10/1

/200

2

1/1/

2007

4/1/

2007

7/1/

2007

10/1

/200

7

1/1/

2008

4/1/

2008

7/1/

2008

10/1

/200

8

1/1/

2009

4/1/

2009

-0.5

0.0

0.5

1.0

370

380

390

δ13

C(C

O2),

‰

δ18O

(CO

2), ‰

CARIBIC: lat. 14 to 20 N lat. 20 to 35 N lat. 35 to 55 N

Stations: MLO KUM IZO MHD

CONTRAIL: lat. 30 to 40 N

CO

2, pp

m

3. CO2 signals in the free troposphere and upper troposphere, latitudinal distribution.

18

0.0026 0.0027 0.0028

-8.6

-8.4

-8.2

-8.0

-7.8

CARIBIC-1 CARIBIC-2 KUM, monthly means, 1995 to 2007

1/CO2, ppm-1

3. Correlated variability in CO2 and δ13C(CO2) in free troposphere and upper troposphere

19

variations in CO2 reflected by d13C(CO2) Different trend slopes for different seasons

2.56 2.58 2.60 2.62-8.6

-8.5

-8.4

-8.3

-8.2

-8.1

-8.0

-7.9

-7.8

2.58 2.60 2.62 2.64 2.66-8.6

-8.4

-8.2

-8.0

-7.8

detrended data:y = 8.000(468) X- 29.2 (1.2)R2 = 0.87

δ13

C(C

O2),

‰

1000/CO2, ppm-1

y = 7.819(452) X - 28.6 (1.2)R2 = 0.88

de-trended data:y = 6.095(164) X - 24.2(0.4)

R2 = 0.93

August to October, 2007Flights 240 to 253

February to April, 2007Flights 220 to 229

δ13C

(CO

2), ‰

1000/CO2, ppm-1

y = 6.465(186) X - 25.1(0.5)R2 = 0.93

CARIBIC-2 :

0.00261 0.00262 0.00263 0.00264

-8.28

-8.22

-8.16

-8.10

δ13C

(CO

2), ‰

1/CO2, ppm-1

Flight Frankfurt-Toronto-Frankfurt (Sept. 2007), latitudes 44 to 54 oN, only UT and tropospheric air.

1/1/2003 1/1/2004 1/1/2005 1/1/2006365

370

375

380

385

390

-8.6

-8.4

-8.2

-8.0

-7.8

-7.6

2.60 2.62 2.64 2.66 2.68 2.70 2.72

-8.6

-8.4

-8.2

-8.0

-7.8 CO

2

CO

2, pp

m

Date, MM/DD/YYYY

δ13C(CO2)

δ13C

(CO

2), ‰

April 2004 to September 2004

δ13C

(CO

2), ‰

1000/CO2, ppm-1

Oct 2003 to March 2004

Mace Head:

3. Trends in δ13C(CO2) due to source and sink effects

20

(Data de-trended for 1/01/2007).

The trend for CARIBIC-1 agrees with the trend for CARIBIC-2.

2.58 2.60 2.62 2.64 2.66-8.6

-8.4

-8.2

-8.0

CARIBIC-1y = 6.914(103) X - 26.4(0.3)R2 = 0.95

δ13C

(CO

2), ‰

1000/CO2, ppm-1

CARIBIC-2y = 6.615(124) X - 25.6(0.3)R2 = 0.94

3. Correlated variability in CO2 and δ13C(CO2) in FT and UT over a long period of time

21

Different flight routes in 2007 and 2008:Larger variability in 2008, both higher values (presumably more SH air) and also lower values (more plumes) than in 2007.

d18O(CO2) data: just scatter or systematic

structure?

360 370 380 390-1.0

-0.5

0.0

0.5

1.0

380 390-1.0

-0.5

0.0

0.5

1.0

380 390

CARIBIC-1 CARIBIC-2

δ18O

(CO

2), ‰

CO2, ppm

δ18O

(CO

2), ‰

CO2, ppm

2007 2008

CO2, ppm

CARIBIC-1 CARIBIC-2

3. Variability in d18O(CO2) in FT and UT

22

-90 -60 -30 0 30 60 90-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

SPO PSASMO

CHRMLOIZO

AZRMHD

BRWZER

δ18(C

O2),

‰

Latitide

SPO

Global d18O(CO2) seasonal cycle.

Shown are the mean values and the amplitudes, averaged for 2003 to 2005.

CARIBIC-2: FT and UT samples MLO and MHD: monthly means, 1999-2000.

360 370 380 390

-1.5

-1.0

-0.5

0.0

0.5

1.0

MLO MHD CARIBIC-2

δ18O

(CO

2), ‰

CO2, ppm

d18O(CO2) of FT and UT air reflect conditions where CO2 was in contact with the surface.

3. Global distribution of d18O(CO2) and CARIBIC data

23

Conclusions 3

• The variability of CO2 signals in the FT and UT is due to mixing of different air masses affected by sources and sinks (the matter of atmospheric transport) and the seasonal variability of sources and sinks in NH. Also plumes are play a role. Role of LMS-back flux is limited;

• Isotopes directly reveal the processes for CO2 variability. Without isotopes, one may imply rather a similarity of air masses in the FT and UT or data scatter;

• CARIBIC signals in the FT and UT being similar to the signals by tropical stations in NH show little latitudinal gradient;

• Explaining/describing CO2 and isotope signals of the FT and UT region in detail will require advanced coupled biosphere-ocean-atmosphere models.

24

375

380

385

3900 50 100 150 200 250 300 350

CARIBIC-1 CARIBIC-2

CO

2, ppm

-8.4

-8.2

-8.0 Latitudes 10 -60oN

δ13C

(CO

2), ‰

0 50 100 150 200 250 300 350-1.0

-0.5

0.0

0.5

1.0

Day of the year

δ18O

(CO

2), ‰

25%75%50%

95%

5%

375

380

385

390

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

CO

2, ppm

-8.4

-8.2

-8.0

δ13C

(CO

2), ‰

Feb

Mar

Apr

May Jun

Jul

Aug

Sep Oct

Nov

Dec

-1.0

-0.5

0.0

0.5

1.0

δ18O

(CO

2), ‰

Jan

Jan

MLO, 1999 - 2007 KUM, 1999 - 2007

CARIBIC-2: 2007- 2009, lat. 14 -60oN

-8.4

-8.2

-8.0

4. CARIBIC data: Seasonality in the FT and UT.

25

• At the flight altitudes there should be a little latitudinal gradient of CO2 signals over latitudes in NH, expect the summer period.

• What we detect are mixing effects, plumes and UT/LMS mixing.

From Miyazaki et al. (2008) JGR, 113, D15301, doi:10.1029/2007JD009557

4. Global tropospheric circulation and CO2signals at flight altitudes

26

• CARIBIC provided unique isotope data for the UT/LMS and tropical FT, with ~1 month resolution. CARIBIC-1 covers 1999 to April 2002 (~250 km/per sample), with high quality d13C(CO2) data. CARIBIC-2 (April 2007 –March 2009) provided reliable d13C(CO2) and d18O(CO2) data with high-resolution (~15 km/sample).

• CARIBIC-2 demonstrates detailed trends at the UT/LMS region, both for CO2, d13C(CO2) and d18O(CO2). For the first time it is demonstrated that global-scale variability in air mass origin and GHG signals are reflected by d13C(CO2) and d18O(CO2). Besides the UT/LMS mixing, correlations arise from different degrees of mixing background air with air masses affected by sources and sinks, over the distance up to 8000 km and also over different seasons.

• By filtering out LMS data, the data for the FT and UT were obtained. The data and trends agree well with the data of NOAA stations in NH tropics. This is in agreement with global atmospheric transport, mostly uplift and transport of tropical air masses.

• d18O(CO2) data reflect air mixing in the free troposphere and UT/LMS region. d18O(CO2) is a principally different tracer than other long lived chemical tracers (CO2, N2O, SF6). The distribution of d18O(CO2) in the UT/LMS region can be used as independent tracer to validate description of global transport and UT/LMS mixing in models.

Summary and outlook