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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.,
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).
►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.
Modeling the line positions improved by factor of 10!
Albert et al. (almost submitted)
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)!
2ν3 good for ground-based retrievals
(empirical E″ lostin reformating)
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
hope to see new assignments by inspection!
Solve for empirical lower state energies using line intensities measured
at different temperatures
Kassi, Gao, Romanini and Campargue (in press).
3 2 1
Need theoretical modeling to understand assignments!
• 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
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
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
REGION (cm-1)NEW POSITIONS AND INTENSITIES
Apply ν3 calculated widths and temp. dep
Then replacewith available measurements
New N2-broadening at 1.66 um + ???
(3000 out of 250000 transitions)
different line broadening parameters
Can’t retrieve right O2 abundance
inaccurate line parameters?
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)
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.
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.
Ciurylo and Szudy, JQSRT 1997
Alternative to Voigt profiles
Need consensus about best line shape!
From Predoi-Cross in press
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.
Left: measured with
speed dependence Voigt vs Voigt
Black: ECS calculated mixing
Gray: Measured Predoi-Cross et al.
R & P similar to Q at each m
Predoi-Cross et al. in press
Tran and Hartmann in press
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
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.
Rosenkranz: good enough for atmosphere?
Tran and Hartmann 2008 or Predoi-Cross et al. 2008