Near Infrared CO
This presentation is the property of its rightful owner.
Sponsored Links
1 / 36

Near Infrared CO 2 Spectral Database Charles E. Miller, Linda R. Brown, and Robert A. Toth PowerPoint PPT Presentation


  • 41 Views
  • Uploaded on
  • Presentation posted in: General

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

Download Presentation

Near Infrared CO 2 Spectral Database Charles E. Miller, Linda R. Brown, and Robert A. Toth

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Near infrared co 2 spectral database charles e miller linda r brown and robert a toth

Near Infrared CO2 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 National Aeronautics and Space Administration. 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 National Science Foundation 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.


According to herzberg

According to Herzberg…

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

The Spectrum of CO2 Below 1.25 m

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


According to herzberg1

According to Herzberg…

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

The Spectrum of CO2 Below 1.25 m

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

Toth et al., JQSRT109, 906 (2008)

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

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

Toth et al., J. Mol. Spectrosc. 243, 43 (2007)

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

Toth et al., J. Mol. Spectrosc. 239, 243 (2006)

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

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)


Near infrared co 2 spectral database charles e miller linda r brown and robert a toth

Return global

XCO2 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

CO2

O2

CO

CO

O

Column

Abundance

Path

Dependent

Ratio

XCO2

Path Independent

Mixing Ratio

Remote Sensing of GHGs at the Sub-1% Level Challenges Spectroscopic Databases


How well can we retrieve co 2 circa 1990

How well can we retrieve CO2? - Circa 1990

  • Wallace and Livingston’s seminal work on CO2 remote sensing [1990] with the Kitt Peak FTS revealed deficiencies in the CO2 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

Improved Solar Spectra Retrievals circa 2002

  • Kitt Peak solar data reanalyzed

    • Improved retrieval algorithm

    • Improved HITRAN 2000 database

    • (HITRAN 1992 + CO2 DND list)

  • Results

    • Systematic residuals in spectra

    • +5.8% biasbetween observed and in situ column amounts

    • 0.5%precisionincolumn CO2

    • "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

Ideal 1:1 Line

Uncorrected

Washenfelder et al. (2006) Park Falls WI The TCCON Prototype

  • New data acquisition hardware and methodology (based around Bruker 125 HR)

  • Results

    • 0.1% XCO2 precision

    • Systematic residuals persist

      • +2.12% bias for 30013

      • +2.40% bias for 30012

“Systematic differences attributed to known uncertainties in the CO2 line strengths and pressure broadened widths”

Washenfelder et al., JGeophys. Res. 111 D22305 (2006)


Co 2 nomenclature

CO2 Nomenclature

Vib. Band Notation follows the HITRAN convention ABCDEwhere A = No. v1 quanta B = No. v2 quanta C = v2 vib ang mom D = No. v3 quanta E = 1 : normal E  1: Fermi res.

Isotopomer Nomenclature: 16O12C16O  626 16O13C16O  636 16O12C18O  628 16O12C17O  627 16O13C18O  638 16O13C17O  637 18O12C18O  828 18O12C17O  827


Kitt peak fts used for lab studies

Kitt Peak FTS used for lab studies


Improving laboratory accuracies requires precise knowledge control of the experimental state

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

Four

Temp

Probes

(PRT)

going

Inside

the

Cell

Goal for Experimental Uncertainties:

Pressure:0.01 Torr (if P > 10 Torr)

Temperature:0.1 K

Path: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)


1 determining the complete spectrum

1. Determining the Complete Spectrum

Accurate CO2 remote sensing to 0.3% requires knowledge of all absorption features that contribute to the CO2 absorption spectrum at the level of approximately 0.1% of Imax

Examination of the known NIR CO2 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

Simulations from HITRAN04

Linear

Log


1 determining the complete spectrum1

1. Determining the Complete Spectrum

30013

16O12C16O = 626

30012

30014

30011

Miller & Brown, J. Mol. Spectrosc. 228, 329 (2004)

Path = 97 m

Pres = 2.06 Torr

Temp= 294 K

C2H2 in 2nd cell to calibrate line positions


Determining the complete spectrum characterize isotopologue transitions

Determining the Complete Spectrum: Characterize Isotopologue Transitions

In natural CO2

16O12C18O < 0.4 % 18O12C18O < 0.0004 %

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

The 2ν3 band of 628 is allowed, but not for

626, 828.

Note: These 828 bands are not in HITRAN 2004

626

2ν3

Toth et al., J. Mol. Spectrosc. 243, 43 (2007)

626: 15% 16O12C16O

628: 48% 16O12C18O

828: 33% 18O12C18O


Determining the complete spectrum characterize isotopologue transitions1

Determining the Complete Spectrum: Characterize Isotopologue Transitions

Toth et al., J. Mol. Spectrosc. 243, 43 (2007)

626

828

628

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

Note: These 828 lines are not in HITRAN 2004

626: 15%

628: 48%

828: 37%


2 improved line positions absolute uncertainties 0 0001 cm 1

2. Improved Line PositionsAbsolute Uncertainties < 0.0001 cm-1

s = 5x10-5 cm-1

Miller & Brown, J. Mol. Spectrosc. 228, 329 (2004)

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


3 measured line intensities of 125 bands

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 of626

Toth et al.,

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

21 bands of 628

8 bands of 627

25 bands of 828

626

628


3 measured line intensities of 125 bands1

Intensities for NIR CO2 bands from multiple laboratories agree at the sub-1% value

A more accurate intercomparison requires specific line shape specification

Speed dependence

Line mixing

3. Measured line intensities of 125 Bands

626

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


4 5 self broadened widths and pressure shifts 15 bands of 626

4. & 5. Self-broadened widths and pressure-shifts15 bands of 626

Fermi Triad and ν2+2ν3

4700 – 5400 cm-1

Fermi Tetrad and 3ν3

6000 – 7000 cm-1

(in cm-1/atm)

Self-

Widths

Note

vibrational

dependence

Toth et al., J. Mol. Spectrosc. 239, 243 (2006)

Self-

Shifts

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


4 5 air broadened widths and pressure shifts 626

4. & 5. Air-broadened widths and pressure-shifts626

Fermi Triad and ν2+2ν3

4700 – 5400 cm-1

Fermi Tetrad and 3ν3

6000 – 7000 cm-1

(in cm-1/atm)

Air

Widths

Note

vibrational

dependence

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

Air-

Shifts

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


Validate lab results with atmospheric data

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

Small Changes in Widths Affect Retrievals at High Airmass

Test Line List B

Test Line List A


Accuracy of 0 3 using new voigt line list

Accuracy of ± 0.3% using new Voigt line list

Precision ~0.1% [Washenfelder et al. 2006]


Near infrared co 2 spectral database charles e miller linda r brown and robert a toth

Active Remote Sensing of CO2 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)

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

Line Positions:

ni = n0 + B(J(J+1)) + D(J(J+1))2 + H(J(J+1))3 + …

ni resonant frequency

n0 band origin

B, D, H rotational constants

Jrotational quantum number

Line Shape Parameters:

i = a1 + a2m + a3m2 +a4m3 + …..

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

Line Intensities:

Si = (ni/n0)(Sv/Li) exp(-hcEi″/kT)[1-exp(hcvi/kT)].F

Si,observed individual line intensity

Sv vibrational band intensity,

Li Hönl-London factor, where li= (m2-l″2)/|m| for CO2

m = J″+1 for the R branch, m = -J″ for the P branch

J″lower-state rotational quantum number.

langular momentum quantum number.

Qr lower state rotational partition function at T0=296 K

Ei″ lower state rotational energy

F Herman-Wallis factor = [1+A1m+A2m2+A3m3]


Line shape problems line mixing occurs in co2 p and r branches

Line Shape Problems!Line Mixing Occurs in CO2 P and R Branches

Miller et al. Comptes Rendus Physique 6 (2005) 876-887.


Multispectral fitting of the 30012 spectrum

Multispectral Fitting of the30012 Spectrum

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


Co 2 line mixing coefficients

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

CO2 Line Mixing Coefficients

Off diagonal relaxation matrix

Rosenkranz


Line mixing speed dependence observed for self and air broadened spectra

Line Mixing & Speed Dependence Observed for Self- and Air-broadened Spectra


Conclusions

Accurate remote sensing of CO2 is critical for climate change science

CO2 remote sensing poses a significant spectroscopic and algorithm challenge

This is NOT YET a solved problem

Consideration of strong 16O12C16O (626) transitions alone is insufficient

Must include hot bands

Must include 16O13C16O (636), 16O12C18O (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

Conclusions


Kitt peak co conspirators

Kitt Peak Co-Conspirators

Chris Benner

(W&M)

Malathy Devi

(LaRC)

Not shown

Linda Brown

Bob Toth

(JPL)

Mike Dulick

(KPNO)

$$$ NASA, NSF


Backup

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)

Isotopic Fractionation in Martian CO20.2% precision desired

*

*

*

*


Unanticipated behavior for high j transitions

638

Unanticipated Behavior for High-J Transitions

High-J transitions may show large (>10-4 cm-1), unexpected deviations from their predicted positions due to

  • Poor spectroscopic parameter extrapolations

  • Perturbations not observed at low-J

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

636

This work – R92

Miller & Brown, J. Mol. Spectrosc. 228, 329 (2004)

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

626


Uncharacterized high j perturbations may lead to gross retrieval errors

Uncharacterized High-J Perturbations May Lead to Gross Retrieval Errors

Short scans of CO2 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

Filling the 2 um Atmospheric Window (1/2)

13CO2 constitutes only ~1% of the natural CO2

Isotopic substitution shifts the band centers in the Fermi triad region such that the 13CO2 bands effectively fill the 2 um (5000 cm-1) atmospheric windows

  • Significant radiative impact under saturated absorption conditions

    The allowed 2v3 band of 638 (NEW) is seen in the 4300 – 4700 cm-1 window

626

CO

C2H2

636

NEW

CO

C2H2


  • Login