WP2. Volatile Organic compounds and CFC-substitutes in the troposphere from FTIR spectra Task 2.1: Retrievals of CH3OH and CH3Cl

Task 2.2: Re-analysis of C2H4, C2H6 and H2CO with improved spectroscopy

Reunion data Team: C. Vigouroux, M. De Mazière, F. Desmet, B. Dils, C. Hermans, N. Kumps, B. Langerock, F. Scolas, (BIRA-IASB); J.-M. Metzger (Univ. La Réunion)

C2H4 : - Jungfraujoch data: M. Mahieu (Ulg)

- IMAGES model: T. Stavrakou J.-F. Müller (BIRA-IASB)

AGACC-II meetingBrussels, 18th December, 2013

Task 2.1: Retrievals of CH3OH and CH3Cl

CH3OH: Vigouroux et al., ACP, 2012 & Stavrakou et al., ACP, 2011

Jan10 Apr10 Jul10 Oct10 Jan110

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CH

3O

H T

otal

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umn

(mol

ec/c

m2)

Apr09 Jul09 Oct09 Jan100

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CH

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otal

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IMAGES optimized using IASI datawithout BB emissions

In Stavrakou et al., ACP, 2011: inversion of the 2009 IASI data, in

order to improve the different sources of CH3OH in IMAGES:

- biogenic & pyrogenic sources reduced: globally 50% and 20% resp.

- improved the seasonality agreement with FTIR

FTIRIMAGESw/o biomass burning

But, IMAGES too low in Sept-Oct.

CH3OH: very good correlation

with CO during the biomass burning BB season (August-November; peak in October); Vigouroux et al., 2012.

- BB is an important source of

CH3OH at Reunion Island1 1.5 2 2.5 3

x 1018

0

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3x 10

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CO

CH

3O

H

R = 0.20 (Jan-Jun)

R = 0.90 (Aug-Nov)

IMAGES underestimates all BB species at Reunion Island in the Sept-

Oct period (C2H6, CO, CH3OH, HCOOH):

- Underestimation of the fire emission database (GFED3)

Short lifetime of CH3OH (6 d.): an underestimation of GFED3

occurs in the southern Africa/ Madagascar region.

Task 2.1: Retrievals of CH3OH and CH3Cl

Task 2.1: Retrievals of CH3OH and CH3Cl

New: - One more year of data at St-Denis with Bruker 120M (2011)

- Maïdo measurements in 2013

Jan09 Jan10 Jan11 Jan120

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CH3OH total columns at St-Denis

Confirm CH3OH peak in October.

Few measurements at Maïdo during the BB period.

Apr13 Jul13 Oct13 Jan140

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FTIRIMAGES

Task 2.1: Retrievals of CH3OH and CH3Cl

CH3OH: summary on the seasonal cycle

2 4 6 8 10 120

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tota

l col

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FTIR St-Denis 2009-2011IMAGES model 2009-2010FTIR Maïdo 2013FTIR Maïdo + a priori shift

Overestimation of IMAGES in wet season (without optimization of sources as made in 2009 with IASI)

FTIR: good agreement in the wet season (less influenced by inter-annual variability), between the 2 sites.

Peak in October at both sites, smaller amplitude with IMAGES.

Next version of GFED will include agricultural fires, which are (unfortunately) numerous in… Madagascar… in October !

Task 2.1: Retrievals of CH3OH and CH3Cl

CH3Cl: first attempt of retrieval strategy: 2967.0-2967.8 cm-1;

spectroscopic linelist from M. Mahieu (HITRAN 2004 for CH4, CH3Cl

from A. Perrin).

2967.1 2967.2 2967.3 2967.4 2967.5 2967.6 2967.7 2967.8

0

10

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90 -3

-2.5

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-4

0.1

0.8

Weak spectral signature; random noise is an issue, as well as interfering species.

H20

H20 CH4, H2OC2H6

Task 2.1: Retrievals of CH3OH and CH3Cl

CH3Cl: improvement in the Signal to Noise Ratio from Bruker 120M to

Bruker 125HR (especially after April 2013), improves the residuals.

Jan09 Jan10 Jan11 Jan12 Jan13 Jan14-0.5

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mol

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Bruker 120MBruker 125HRMaïdo

Jan09 Jan10 Jan11 Jan12 Jan13 Jan140.1

0.2

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0.5RMS

Bruker 120MBruker 125HRMaïdo

Therefore, the scatter in the

CH3Cl columns is nicely

reduced from Bruker 120M to Bruker 125HR (especially after April 2013), and at Maïdo.

Task 2.1: Retrievals of CH3OH and CH3Cl

CH3Cl: seasonal cycle

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mol

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St-Denis Bruker 120MSt-Denis Bruker 125HRMaïdo

St-Denis Bruker 120M: seems too chaotic; probably we see mainly noise.

St-Denis Bruker 125HR: max. in August is observed, large amplitude.

Maïdo columns should be smaller than St-Denis columns ! Probably high systematic bias due to interfering species at St-

Denis (H2O ?).

Max. April and August, small amplitude.

Task 2.1: Retrievals of CH3OH and CH3Cl

Maïdo columns should be smaller than St-Denis columns

Comparisons St-Denis/Maïdo look better after April 2013 (when SNR was improved)

0 2 4 6 8 10 12

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St-Denis Bruker 120MSt-Denis Bruker 125HRSt-Denis > April 2013Maïdo

Seasonal cycles in the literature: Yoshida et al., 2006 (surface meas.):

- max. in March & August at 14°S, amplitude < 5% - max. in July-August at 40°S, amplitude ~10%

Task 2.2: C2H4

C2H4: many tests on retrieval strategy

Final micro-window: 948.8 - 952.4 cm-1.

Very weak absorption signatures, and the strongest one is found at

the edge of a CO2 line.

CO2

949 949.5 950 950.5 951 951.5 952

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St-Denis

Slope:H2O

Task 2.2: C2H4

Maïdo: improved SNR with Bruker 125 HR; less H2O due to altitude.

CO2

Slope:H2O

St-Denis Maïdo

Much reduced slope

Task 2.2: C2H4

St-Denis (Bruker 120M): large scatter and some negative columns.

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mol

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C2H

4 total columns at Saint-Denis

IMAGESFTIR

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5

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14 C2H

4 total columns at Maïdo

Maïdo

Maïdo (Bruker 125HR, less H2O): still large scatter, no negative values.

Scatter real (lifetime ~1-2 days) ? And/Or too large random error: to be calculated with SFIT4.

Try more filtering ? Need more data at Maïdo.

Task 2.2: C2H4

0 2 4 6 8 10 12 140

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14C2H

4 seasonal cycle; Reunion Island

mol

ec/c

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FTIR St-Denis 2009-2011IMAGES model 2009-2011FTIR Maïdo 2013

C2H4: seasonal cycle at Reunion Island

St-Denis: surprising good agreement with IMAGES in Dec-Aug. (considering FTIR large scatter).

Maïdo columns should be lower than St-Denis: bias

due to H2O ?

High values in April-May at Maïdo due to a few points, need to be confirmed.

FTIR has a max. in Sep-Oct at both sites; not seen in IMAGES: Agreement with the (currently missing in model) biomass

burning from agriculture in Madagascar ! (lifetime C2H4: 1-2 days)

Task 2.2: C2H4 at Jungfraujoch

C2H4 at Jungfraujoch: using the Reunion Island settings.

Jan00 Jan02 Jan04 Jan06 Jan08 Jan10 Jan12 Jan140

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C2H

4 total columns at Jungfraujoch

IMAGESFTIR

A significant negative trend is observed.

Results promising ! H2O is much lower at Jungfraujoch.

Task 2.2: C2H4 at Jungfraujoch

C2H4 at Jungfraujoch: seasonal cycle

Jan09 Jan10 Jan11 Jan12 Jan130

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C2H

4 total columns at Jungfraujoch

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tota

l col

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FTIRIMAGES

Phase of the seasonal cycle in agreement with IMAGES

Amplitude is much larger with the model

The FTIR retrieval strategies optimized for many VOCs in the first

years of AGACC-II (CH3OH, HCHO, HCOOH, C2H6, HCN, C2H2) have

been or will be soon applied to the recent measurements. The procedure is much quicker with the tools implemented within the NORS project (B. Langerock).

C2H4: a retrieval strategy has been implemented and seems

promising at Jungfraujoch. Some efforts still needed at Reunion Island to understand/correct the large scatter, but seasonal cycle seems good.

We are very curious to compare our Reunion Island time-series of biomass burning species with IMAGES when the GFED4 database, including agricultural fires, will be distributed !

Summary & perspectives

Summary & perspectives

The quality of the spectra (SNR) has been greatly improved with the Bruker 125HR, which can be critical for molecules with low spectral signatures, close to the detection limit.

At Maïdo, the altitude of the site reduces the error due to interfering species (e.g water vapor and isotopologues).

CH3Cl: using the most recent measurements (i.e with improved SNR),

it seems that there is a hope to observe this molecule. What is needed now is 1) more measurements; 2) spectroscopic tests

(HITRAN2012; CH3Cl line-mixing); 3) better check of H2O interference.

Perspectives for AGACCII:

PAN (already tested without success up to now) and acetone will be tested with the new software (SFIT4): allows for HITRAN 2012

and for CO2 line-mixing which was one of the problem for PAN

retrievals.

Duflot, V., et al.: HCN and C2H2 from IASI, AMT, 2013.

Vigouroux, C.: FTIR measurements of VOCs: precious data for model and satellite validation, NDACC newsletter, 2013.

Not related to AGACC-II but very important for NDACC FTIR in general, and BIRA-IASB and ULg in particular:

Thanks to our work on FTIR ozone trends at 8 NDACC stations, we join the SI2N initiative whose aim is to provide “much improved knowledge of ozone changes for the next WMO Scientific Assessment of Ozone depletion”.

- Participation in the three SI2N overview papers:

Hassler et al.: Ozone profile measurements: techniques, uncertainties and availability, AMTD, 2013; Lambert et al.; and Harris et al., in preparation, before spring 2014.

- Participation in the WMO Assessment in 2014.

WP 5: Outreach in 2013

Thank you !

Task 2.1: Retrievals of CH3OH and CH3Cl

CH3Cl: first attempt of retrieval strategy, not really a big success…

but some hope.

Future: focus on optimizing the data after April 2013 at Maïdo and St-Denis: need more data…

- Try HITRAN 2012 (with SFIT4)

- Try G. Toon: CH3Cl line-mixing

problem, propose an « empirical way » of treating this.

- improve H2O treatment (now some

spectra shows residuals)

And/or filtering on systematic

residuals when H2O is not well

reproduced,…

Not related to AGACC-II but very important for NDACC FTIR in general, and BIRA-IASB in

particular:

Join the SI2N initiative: Over three and a half decades have passed since Molina and

Rowland postulated that anthropogenic chlorofluorocarbons could deplete the ozone layer

(Molina and Rowland, 1975), and over two and a half decades have passed since the

discovery of the ozone hole (Farman et al., 1985). In this time, the countries of the world

have produced and signed the Montreal Protocol limiting the production of ozone-depleting

substances (ODSs), and leading to reductions in their atmospheric concentrations (WMO,

2011).. As we proceed towards the expected ozone recovery from the influences of ODSs,

scientific questions concerning the detection and attribution of that recovery have come to

the fore. Answering many of these questions will require a critical examination of the

pattern and time sequence of ozone change. Thus, accurate knowledge of the altitude,

latitude, and seasonal structure of the ozone response is required. It is also critical that the

quality of the measurements used is as high as possible, and that the quality is known.

Outreach in 2013