T2.1_Miller - NIR CO2 Database

Near Infrared CO

2

Spectral Database

Charles E. Miller, Linda R. Brown, and Robert A. Toth

Jet Propulsion Laboratory, California Institute of Technology,

4800 Oak Grove Dr., Pasadena, California 91109

D. Chris Benner, V. Malathy Devi

The College of William and Mary, Box 8795, Williamsburg, Virginia 23187-8795, U.S.A

Acknowledgments

The research at the Jet Propulsion Laboratory (JPL), California Institute of Technology, was performed under contract with N ational A eronautics and S pace A dministration. We thank NASA ’s Upper Atmosphere Research Program for support of the McMath-Pierce laboratory facility. CEM thanks NASA ’s Tropospheric Chemistry and Atmospheric Composition programs for support. The material presented in this investigation is based upon work supported by the N ational S cience F oundation under Grant No. ATM-0338475 to the College of William and Mary. The authors express sincere appreciation to M. Dulick of NOAO (National Optical Astronomy Observatory) for the assistance in obtaining the data. We also thank

Gregory DiComo for assistance in setting up the multispectrum solution.

1 10 th HITRAN Database Conference

Cambridge MA June 22, 2008

Jet Propulsion Laboratory

California Institute of Technology

According to Herzberg…

“The spectrum of carbon dioxide has been studied exhaustively by a large number of investigators.”

The Spectrum of CO

2

Below 1.25

J. Opt. Soc. Am. 43 , 1037 (1953) m





According to Herzberg…

“The spectrum of carbon dioxide has been studied exhaustively by a large number of investigators.”

The Spectrum of CO

2

Below 1.25

J. Opt. Soc. Am. 43 , 1037 (1953) m

Toth et al., JQSRT 109 , 906 (2008)

Toth et al., J. Mol. Spectrosc. 246 , 133 (2007)

Malathy Devi et al., J. Mol. Spectrosc. 245 , 52 (2007)


Malathy Devi et al., J. Mol. Spectrosc. 242 , 90 (2007)



Miller et al., CR Physique 6 , 876 (2005)

Miller et al., J. Mol. Spectrosc. 228 , 329 (2004)

Miller et al., J. Mol. Spectrosc. 228 , 355 (2004)





Return global

X

CO2

data with

0.3% precision

Miller et al., JGR 112, D10314 (2007)





Remote Sensing of GHGs at the Sub-1% Level

Challenges Spectroscopic Databases

Measured Spectra

CO

2

Column

Abundance

Path

Dependent

O

2



Ratio

X

CO2

Path Independent

Mixing Ratio



How well can we retrieve CO

2

? - Circa 1990

Wallace and Livingston’s seminal work on CO

2 remote sensing [1990] with the

Kitt Peak FTS revealed deficiencies in the CO

2 spectral database

( HITRAN 1986) .

Insufficient NIR Spectroscopic

Reference Standard Accuracy

1. Incomplete knowledge of spectrum

2. Inadequate position knowledge

3. Intensities known to 5 – 20% unc.

4. Unvalidated air-widths

5. No pressure shifts

Wallace & Livingston, J. Geophys. Res. D 95 , 9823 (1990)





Improved Solar Spectra Retrievals circa 2002

Kitt Peak solar data reanalyzed

•

Improved retrieval algorithm

•

Improved HITRAN 2000 database

( HITRAN 1992 + CO

2

DND list )

Results

•

Systematic residuals in spectra

•

+5.8% bias between observed and in situ column amounts

•

0.5% precision in column CO

2

"Remaining errors are dominated by deficiencies in the spectroscopic line lists"

Yang et al., Geophys. Res. Lett . 29 (10) GL014537 (2002)





Washenfelder et al. (2006) Park Falls WI

The TCCON Prototype

New data acquisition hardware and methodology (based around

Bruker 125 HR)

Results

• 0.1% XCO

2 precision

• Systematic residuals persist

• +2.12% bias for 30013

• +2.40% bias for 30012

“Systematic differences attributed to known uncertainties in the CO

2 line strengths and pressure broadened widths”

Uncorrected

Washenfelder et al., J Geophys. Res . 111 D22305 (2006)





CO

2

Nomenclature

Vib. Band Notation follows the HITRAN convention ABCDE where

A = No. v

1

B = No. v

2

C = v

2 quanta quanta vib ang mom

D = No. v

3 quanta

E = 1 : normal

E



1: Fermi res.

Isotopomer

Nomenclature :

16

16

16

16

16

16

18

18

O 12 C 16

O 13 C 16

O 12 C 18

O 12 C 17

O



626

O



636

O



628

O



627

O 13 C 18 O



638

O

O

O

13

12

12

C

C

C

17

18

17

O



637

O



828

O



827

Isotopomer

626

636

628

627

638

637

828

827

Natural

Abundance

0.98420

0.01106

0.0039471

0.000734

0.00004434

0.00000825

0.0000039573

0.00000147





Kitt Peak FTS used for lab studies





Improving Laboratory Accuracies Requires

Precise Knowledge/Control of the Experimental State

• Pristine new cells – no contamination

• Temperature monitoring inside the cell

• Isotopic enriched samples

• Mass spectrometric standard samples

• Stable spectrometer performance

Goal for Experimental Uncertainties:

Pressure:

Path:



0.01 Torr (if P > 10 Torr)

Temperature:



0.1 K



2 mm (0.1%)

Composition :



0.05%

SNR : >1000

Resolution : 0.011 cm -1

100% Trans :



0.1%

0% Trans :



0.1%

Positions :



0.0001 cm -1

Intensity :



0.1% (Relative)



Four

Temp

Probes

(PRT) going

Inside the

Cell



1. Determining the Complete Spectrum

Accurate CO

2 remote sensing to 0.3% requires knowledge of all absorption features that contribute to the CO

2 absorption spectrum at the level of approximately 0.1% of I max

Examination of the known NIR CO

2 features on a LOG scale shows that transitions from many weaker bands contribute detectable absorption to the spectrum

Completeness will be a critical requirement for the spectral database

Linear

Log

Simulations from HITRAN04





1. Determining the Complete Spectrum

30014

30013

30012

16 O 12 C 16 O = 626

30011

Path = 97 m

Pres = 2.06 Torr

Temp= 294 K

C

2

H

2 in 2nd cell to calibrate line positions





1. Determining the Complete Spectrum:

Characterize Isotopologue Transitions

In natural CO

2

16 O 12 C 18 O < 0.4 %

18 O 12 C 18 O < 0.0004 %

Note: 628 has 2 x more lines than symmetric isotopologues ( 626 , 828 ) due to different spin statistical weights.

The 2

ν

3 band of 628 is allowed, but not for

626 , 828.

Note : These 828 bands are not in HITRAN 2004

2 ν

3

626 : 15%

628 : 48%

828 : 33%

16 O

16 O

12 C

12 C

16 O

18 O

18 O 12 C 18 O



626



1. Determining the Complete Spectrum:

Characterize Isotopologue Transitions

828 628

The region below 6920 cm -1 would be transparent in models neglecting 18 O species

Note : These 828 lines are not in HITRAN 2004

626

626 : 15%

628 : 48%

828 : 37%





10

2. Improved Line Positions

Absolute Uncertainties < 0.0001 cm -1

5

00031

MB-Vander Auwera s

= 5x10 -5 cm -1

0

-5

-10

-40 -20 0 m

20 40

Line position differences of the experimentally measured line positions of Miller & Brown and Vander Auwera et al .





3. Measured line intensities of 125 Bands

Retrievals : Voigt line shape & line-by-line fitting of individual spectra

% Differences between HITRAN 2004 and new band strengths

Toth et al. J. Mol. Spectrosc. 239, 221 (2006)

Reported 58 band strengths of 626

Toth et al.,

J. Mol. Spectrosc. 243, 43 (2007)

21 bands of 628

8 bands of 627

25 bands of 828

626 5

0

-5

-10

6000

628

7000 2000 3000 4000

Band Center (cm

-1

)

5000





3. Measured line intensities of 125 Bands

• Intensities for NIR CO

2 bands from multiple laboratories agree at the sub-1% value

• A more accurate intercomparison requires specific line shape specification

–

Speed dependence

–

Line mixing

626





4. & 5. Self-broadened widths and pressure-shifts

15 bands of 626

(in cm -1 /atm)

0.13

Self-

Widths

0.12

0.11

0.10

0.09

Note

0.08

vibrational 0.07

dependence

0.06

-80

-0.002

Self-

Shifts

-0.004

-0.006

-0.008

-0.010

-0.012

-80

Fermi Triad and ν

2

+2

4700 – 5400 cm -1

ν

3

Fermi Tetrad and 3

6000

-60

-60

-40

-40

0.13

0.12

0.11

0.10

0.09

20013-00001

20012-00001

20011-00001

21113-01101

21112-01101

21111-01101

01121-01101

0.08

0.07

-20 0 m

20 40 60 80

0.06

-60 -40 -20

-20

0.000

-0.002

-0.004

20013-00001

20012-00001

20011-00001

21113-01101

21112-01101

21111-01101

01121-00001

0 m

-0.006

-0.008

-0.010

-0.012

-0.014

20 40 60 80

-0.016

-60 -40 -20

m = J" for P branch, J"+1 for R branch

– 7000 cm

30014-00001

30013-00001

30012-00001

30011-00001

31113-01101

31112-01101

00031-00001

01131-01101

0 m

20

30014-00001

30013-00001

30012-00001

30011-00001

31113-01101

31112-01101

00031-00001

01131-01101

0 m

20

-1

40

40

ν

3

60

60





4. & 5. Air-broadened widths and pressure-shifts

626

(in cm -1 /atm)

Fermi Triad and ν

2

+2

4700 – 5400 cm -1

ν

3

Air

Widths

0.100

0.095

0.090

0.085

0.080

Note

0.075

0.070

vibrational

0.065

0.060

dependence

-80

-0.001

Air-

Shifts

-0.002

-0.003

-0.004

-0.005

-0.006

-0.007

-0.008

-0.009

-80

20011-00001

20012-00001

20013-00001

21111-01101

21112-01101

21113-01101

-60

-60

-40

20011-00001

20012-00001

20013-00001

21111-01101

21112-01101

21113-01101

-40

-20

-20

0.10

0.09

0.08

0.07

Fermi Tetrad and 3

6000

0 m

20 40 60 80

0.06

-60

-0.002

-0.004

-0.006

-0.008

-0.010

-0.012

-0.014

-60

-40 -20

0 m

20 40 60 80

-40

m = J" for P branch, J"+1 for R branch

-20

– 7000 cm

0 m

30011-00001

30012-00001

30013-00001

30014-00001

30012-00001-Devi et al.

00031-00001

30013-00001-Devi et al.

20

0

30011-00001

30012-00001

30013-00001

30014-00001

00031-00001

30012-00001-Devi et al

30013-00001-Devi et al.

20 m

-1

40

40

ν

3

60

60





Validate lab results with atmospheric data

Observed and calculated balloon-based FTS spectra

JPL MkIV (G. Toon)

29 km Tangent

Height

Top trace:

HITRAN 2004

Right trace:

Current Best line list





Small Changes in Widths Affect

Retrievals at High Airmass

Test Line List A Test Line List B





Accuracy of ± 0.3% using new Voigt line list

Region

Used

2.1 m m

1.6 m m

1.58 m m

Differences Between In Situ and FTS Column CO

2

( Ground - and Balloon -based)

[After Sen et al., 2006 HITRAN Conference]

Bruker 125 HR:Park Falls

Z min

: 0.47 km; SZA: 38.7



HITRAN

2004

JPL

2008

9%

4%

-1%

+0.3%

-0.1%

-0.3%

MkIV (JPL)

Z min

: 31.65 km; SZA: 91.7



HITRAN

2004

JPL

2008

7% +0.2%

Precision ~0.1% [Washenfelder et al. 2006]





Active Remote Sensing of CO

2

Requires

Even Greater Line Shape Accuracy

ASCENDS

ASCOPE

GOSAT-II

P = 269.03 Torr

L = 0.347 m

T = 297.04K.

Candidate transition: R(30) of 20013



00001

@ 2050.967 nm (4875.748 cm -1 )





Improved Multispectrum Fitting

[Benner et al., JQSRT 53, 705 (1995)]

• Fit all lines and spectra simultaneously

• Use quantum mechanical constraints for positions and intensities

• Increases sensitivity to subtle effects in line shapes

• Updated capabilities include non-Voigt line shapes, line mixing, speed dependence (Benner et al., in preparation)

Line Positions: n i n i

= n

0

+ B(J(J+1)) + D(J(J+1)) resonant frequency n

0 band origin

B, D, H rotational constants

2 + H(J(J+1)) 3 + …

J rotational quantum number

Line Shape Parameters:

 i = a

1

+ a

2 m + a

3 m 2 +a

4 m 3 +

…..

Measured half-width at half-max at each line position

Line Intensities:

S i

= ( n i

/ n

0

)(S v

/L i

) exp(-hcE i

″/kT)[1-exp(hcv i

/kT)].F

S i

, observed individual line intensity

S

L v i vibrational band intensity,

Hönl-London factor, where l i

= (m 2

l

″ 2 )/|m| for CO

2 m = J

″+1 for the R branch, m =

-

J

″ for the P branch

J

″ lower-state rotational quantum number. l angular momentum quantum number.

Q r

E i lower state rotational partition function at T0=296 K

″ lower state rotational energy

F Herman-Wallis factor = [1+A

1 m+A

2 m 2 +A

3 m 3 ]





Line Shape Problems!

Line Mixing Occurs in CO2 P and R Branches





Multispectral Fitting of the

30012 Spectrum





CO

2

Line Mixing Coefficients

Rosenkranz

Off diagonal relaxation matrix

• Line mixing observed at 6220 cm

-

1

even though this band has no Q-branch, no perturbations and adjacent lines are spaced by ~ 1 cm

-

1





Line Mixing & Speed Dependence Observed for

Self- and Air-broadened Spectra





Conclusions

• Accurate remote sensing of CO

2 is critical for climate change science

• CO

2 remote sensing poses a significant spectroscopic and algorithm challenge

– This is NOT YET a solved problem

• Consideration of strong 16 O 12 C 16 O (626) transitions alone is insufficient

– Must include hot bands

– Must include 16 O 13 C 16 O (636), 16 O 12 C 18 O (628), etc

• Line shape choice is crucial to simulate high quality spectra within their experimental uncertainty

– Non-Voigt line shapes improve fits 30% - 50% vs Voigt fits

– Line Mixing is needed to remove systematic residuals





Chris Benner

(W&M)

Malathy Devi

(LaRC)

Not shown

Kitt Peak Co-Conspirators

Linda Brown

Bob Toth

(JPL)

$$$ NASA, NSF



Mike Dulick

(KPNO)



Backup





Isotopic Fractionation in Martian CO

2

0.2% precision desired

Grassi et al., Planet. Space Sci . 53 , 1017 (2005)

Measured & modeled PFS/Mars spectra

PFS/Mars Express (2004)



Isotopomer

626

636

628

627

638

637

828

827

Natural

Abundance

0.98420

0.01106

0.0039471

0.000734

*

*

*

*

0.00004434

0.00000825

0.0000039573

0.00000147



Unanticipated Behavior for

High-J Transitions

HighJ transitions may show large (>10 -4 cm unexpected deviations from their predicted

-1 ), positions due to

– Poor spectroscopic parameter extrapolations

– Perturbations not observed at lowJ

Rare isotopologues and hot bands are especially susceptible to these problems since they are much more difficult to characterize accurately

3000

2500

2000

1500

1000

500

0

-500

-60 -40 -20

22211

MB-R92 (e)

MB-R92 (f)

626

0 m

20 40 60

200

0

-200

-400

-600

-800

-1000

-1200

-1400

-1600

-60

40

20

0

-20

-40

-60 -40

-40

636

20012-00001

This work – R92

-20 0 m

20

20012- 00001

This work-R92

This work-Ding

638

40

-20 0 m

20 40

60

60





Uncharacterized High-J Perturbations May Lead to Gross Retrieval Errors

Short scans of CO

2 covering the perturbed R74, R76, R78 and R80 lines in the 20012-00001 band of 626.

The calculated positions refer to unperturbed locations calculated from parameters derived from lower J transitions.

Toth et al., J. Mol. Spectrosc. 239, 221 (2006)





Filling the 2 um Atmospheric Window (1/2)

13 CO

2 constitutes only

~1% of the natural CO

2

Isotopic substitution shifts the band centers in the

Fermi triad region such that the 13 CO

2 bands effectively fill the 2 um

(5000 cm -1 ) atmospheric windows

– Significant radiative impact under saturated absorption conditions

The allowed 2v

3 band of

638 (NEW) is seen in the

4300 – 4700 cm -1 window

C

2

H

2

CO

C

2

H

2

CO

NEW



626

636



T2.1_Miller - NIR CO2 Database

Near Infrared CO

Spectral Database

Return global

data with

0.3% precision

Results

CO

Nomenclature

Kitt Peak FTS used for lab studies

1. Determining the Complete Spectrum

1. Determining the Complete Spectrum

3. Measured line intensities of 125 Bands

3. Measured line intensities of 125 Bands

Validate lab results with atmospheric data

• Fit all lines and spectra simultaneously

• Use quantum mechanical constraints for positions and intensities

• Increases sensitivity to subtle effects in line shapes

• Updated capabilities include non-Voigt line shapes, line mixing, speed dependence (Benner et al., in preparation)

Line Shape Problems!

• Line mixing observed at 6220 cm

even though this band has no Q-branch, no perturbations and adjacent lines are spaced by ~ 1 cm

Kitt Peak Co-Conspirators

Isotopic Fractionation in Martian CO

Related documents

Products

Support

T2.1_Miller - NIR CO2 Database

Near Infrared CO

Spectral Database

Return global

data with

0.3% precision

Results

CO

Nomenclature

Kitt Peak FTS used for lab studies

1. Determining the Complete Spectrum

1. Determining the Complete Spectrum

3. Measured line intensities of 125 Bands

3. Measured line intensities of 125 Bands

Validate lab results with atmospheric data

• Fit all lines and spectra simultaneously

• Use quantum mechanical constraints for positions and intensities

• Increases sensitivity to subtle effects in line shapes

• Updated capabilities include non-Voigt line shapes, line mixing, speed dependence (Benner et al., in preparation)

Line Shape Problems!

• Line mixing observed at 6220 cm

even though this band has no Q-branch, no perturbations and adjacent lines are spaced by ~ 1 cm

Kitt Peak Co-Conspirators

Isotopic Fractionation in Martian CO

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