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New Line Parameters for Near-IR Methane and the Oxygen A-Band presented by Linda R. Brown (JPL)

New Line Parameters for Near-IR Methane and the Oxygen A-Band presented by Linda R. Brown (JPL). World-wide Effort Belgium, Canada, France, Germany, Netherlands, Russia, Switzerland, United States CH 4 : BOUDON et al., NIKITIN et al. , QUACK et al., FRANKENBERG et al.,

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New Line Parameters for Near-IR Methane and the Oxygen A-Band presented by Linda R. Brown (JPL)

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  1. New Line Parameters for Near-IR Methane and the Oxygen A-Bandpresented byLinda R. Brown (JPL) World-wide Effort Belgium, Canada, France, Germany, Netherlands, Russia, Switzerland, United States CH4:BOUDON et al., NIKITIN et al. , QUACK et al., FRANKENBERG et al., ANTONY et al., SMITH et al., PREDOI-CROSS et al., TRAN et al. KASSI et al., GAO et al., LIU et al. O2: TRAN et al., PREDOI-CROSS et al., ROBICHAUD et al., BROWN et al. JPL: Part of the research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA).

  2. Global fit METHANE: The Polyads 1.7 μm 2.3 μm new From Boudon et al. EGU 2008

  3. Much improved analyses using really cold data ►Near-IR spectra at 78 K permitted more Octad bands to be assigned. ►Higher order terms were added to Hamiltonian models for Global fit. Doppler-limited spectra from a Bruker FTS in Zurich (M. Quack) 2700 - 8000 cm-1 Reduced energy (cm-1) vs J: Many new assignments found usingcold (78 K) spectra. ←Pentad ← Octad Modeling the line positions improved by factor of 10! Better predictedspectrum Tetradecad Isocad →

  4. 12CH4 Global modeling: 0–4800 cm-1 Albert et al. (almost submitted)

  5. Octad: measured line intensities Needed to obtain bettermodelling of line intensities top:Log of measured line intensitiesbottom:%(observed – calc) NEED: More and better measurements of weak lines (including 13CH4)!

  6. 12CH4: 4800 - 6300 cm-1:formerly intractable Must assign and model 60 sub-vibrational bands 2ν3 good for ground-based retrievals ↔ • HITRAN 1992: Margolis 1988, 1990: 5500-6184 cm-1: 2684 stronger lines with many empirical lower states • HITRAN 2004: Brown 2005: line positions, weaker intensities: for 4800-5500, 6184 – 9200 cm-1 (empirical E″ lostin reformating) H2O ← Tetradecad 4800 cm-1 6400 NEW Hope: FTS and CRDS spectra at 78 Kelvin. ▪Quack et al. FTS spectra at 78 K : line positions & assignments ▪ Liu et al., Gao et al., Kassi et al. CRDS: Intensities and empirical lower state energy 5852-6181 cm-1 ▪Frankenberg et al. FTS spectra 5998 – 6130 cm-1 (with N2- pressure broadening) Best hope for HITRAN 2008: USE EMPIRICAL LINELISTS? from Kassi et al. accepted

  7. CH4: 6600 - 7700 cm-1:~intractable region Must assign and model 134 sub-vibrational bands Cold spectra: hope to see new assignments by inspection! or Solve for empirical lower state energies using line intensities measured at different temperatures Kassi, Gao, Romanini and Campargue (in press). 3 2 1 Q Need theoretical modeling to understand assignments!

  8. Status of 12CH4 Parameters

  9. Methane Work in Progress

  10. New Pressure Broadeningfor Methane • 7 μm: measured widths, shifts, temp. depend., Line mixing Benner, Devi, Predoi-Cross, Smith….. - in prep. • 3.3 μm ν3: theoretical calculation of widths, shifts and temperature dependence of widths for A and F Antony et al. J. Mol. Spectrosc. in press • 1.6 μm N2-widths and shifts of stronger lines above 5998 cm-1 Frankenberg et al. Atmos. Chem. Phys.-accepted. • Line mixing: weak but needed in atmospheric retrievals: Smith et al. (poster) v4 Tran et al. JQSRT 2006 v4 and v3 Predoi-Cross et al. JMS 2007 v2+v3 Mondelain et al. 2007, 2008 P9 of v3 : temp dependence= 1.2 – 1.5

  11. Line mixing calculations for methane

  12. LINE MIXING + REQUIRED Mondelain et al. 2008:Atmospheric spectra ►Measured and calculated transmissions at a tangent height of ~ 18 km. ►Fitting residuals (observed–calculated) are (from top to bottom) 1) Voigt model with HITRAN values 2) Voigt model with their new line mixing 3) Voigt model with their new temperature dependence exponent 4) a hard model without line mixing (using their new values) 5) a hard model (Rautian) with line mixing and their new temperature dependence exponents. Need Line mixing (Rosenkranz)ζ and Dicke Narrowingβ

  13. Methane for HITRAN 2008under construction REGION (cm-1)NEW POSITIONS AND INTENSITIES • 0 - 4800: 12CH4 global fit • (nothing new for 13CH4) • 3300- 3700: CH3D (and maybe at 6600 cm-1) • 4800- 7700: lots of work in progress, but not ready • NEW Voigt Broadening Parameters Apply ν3 calculated widths and temp. dep Then replacewith available measurements New N2-broadening at 1.66 um + ??? (3000 out of 250000 transitions) • Estimate shifts and use limited measurements • Line mixing: tbd ??

  14. Oxygen A - Band at 760 nm (13122 cm-1) • New effort by Tran & Hartmann: • Still Ordinary Voigt • Full W-matrix Line mixing but with different line broadening parameters • used empirical expression for widths from Yang et al. 2005 • Revised Collision Induced Absorption (CIA) • But still a problem: Can’t retrieve right O2 abundance inaccurate line parameters? missing isotopes? wrong line shapes? (a)Ground-based Atmospheric spectra Park Falls FTS (P. Wennberg) Voigt only : LINE MIXING REQUIRED!!! (b)Tran et al. JGR-Atmos 2006 (c)New: Tran and Hartmann ( in press)

  15. Oxygen A - Band at 760 nm using NIST CRDS (Joe Hodges)Line intensities and positions of P branch retrieved with Galatry profile: Line positions calibrated with atomic K transitions With accuracies better than 0.00005 cm-1 NIST/Caltech/JPL:Robichaud et al. 2008 Intensities measured with NIST samples Ratio of Ints. Others/HITRAN 30 MHz = 0.001 cm-1 Should lower calculated intensities: Compared to HITRAN 2004: NIST CRDS is-0.8% Average of 9 studies is-1.3% (how much of this difference is due to the different line shapes used?) HITRAN line positions (B&P) are within 0.0007 cm-1 of NIST calibrated measurements.

  16. Oxygen A - Band at 760 nm Air-widths Different line shapes produce different values of air-widths: Red: line mixing with speed dependence Green: Voigt with Dicke Narrowing & No line mixing (NIST CRDS) Blue: Voigt with line mixing Which set gives the best accuracies? Above: Robichaud et al. 2008 Air-widths: refit to Yang empirical eq.

  17. O2 Pressure shifts:uncertain because of calibration of wavenumber scale and/or line shape choices? Ciurylo and Szudy, JQSRT 1997 Alternative to Voigt profiles Dicke narrowing? Speed dependence? Need consensus about best line shape! From Predoi-Cross in press

  18. Isotopologues of the Oxygen A - Band at 760 nm Work in progress at NIST/Caltech (Robichaud et al. in prep.) Isotopologues measured with enriched samples using CRDS Positions, many intensities and some “self-broadened” line widths New results for 16O18O and 16O17O will be provided to HITRAN with broadening from the main isotope applied.

  19. Oxygen A - Band at 760 nm Weak line mixing: first order coefficients Left: measured with speed dependence Voigt vs Voigt Black: ECS calculated mixing Gray: Measured Predoi-Cross et al. Measured using Speed depend. Voigt or Voigt R & P similar to Q at each m Predoi-Cross et al. in press Tran and Hartmann in press

  20. Oxygen A - Band at 760 nmNew effort with Kitt Peak FTS lab spectra: Combine Kitt Peak FTS lab data from Brown and Plymate (2000) with new higher pressure scans up to ~ 3 atm. Brown, Pine, Miller Best fit using Rautian (narrowing) with weak line mixing

  21. O2: test with synthetic spectra at infinite resolution Black: synthetic spectrum calculated by Pine using Tran et al. 2006 code Line mixing is full “w” matrix. Pressure = 1 atm of air; path = 1 km Lower panels are differences between top and other calculated spectra (offset by successive increments of - 0.2) --------------------------------------------Green: shows Pine’s software computes the same spectrum as Tran’s code Rust: only Voigt used. Teal: difference with W-matrix and Rosenkranz line mixing Purple: Rosenkranz line mixing adjusted to match the top spectra Brown: 4 other synthetic spectra o were computed at different gas conditions and fitted as test data using multi-spectrum fitting. Didn’t quite match R branch band head. Voigt inadequate! Rosenkranz: good enough for atmosphere?

  22. O2 A-band for HITRAN 2008: • Positions: use Robichaud et al. (NIST-CRDS): isotopes too • Intensities: scaleusing Robichaudet al. or average of many: ±0.5% • Widths: empirical expression Robichaud or Predoi-Cross model • Shifts: ???????? Dependences on line shape model • Dicke narrowing (Robichaud et al. 2008 or Predoi-Cross et al. 2008) • Temp. dependence of widths, shifts, mixing, narrowing: ??? • Line mixing ???? Tran and Hartmann 2008 or Predoi-Cross et al. 2008 • CIA: Trans and Hartmann (2008)

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