1. An accurate and complete empirical line list for water vapor
between 5850 – 7920 cm-1
D. Mondelain, A. Campargue, S. Kassi
Laboratoire Interdisciplinaire de Physique Université Grenoble 1/CNRS
S. Mikhailenko
V.E. Zuev Institute of Atmospheric Optics, Tomsk, Russia

2. Water vapor absorption
Introduction
Remote sensing of the Earth’s atmosphere requires an accurate characterization of the transparency windows
Water vapor absorption =
Local lines
absorption
H20 +
Continuum
absorption
Next talk

3. Outline The CRDS technique and experimental setup
Line list for water vapor in the cm-1 region
Conclusion

4. The CRDS technique

5. Cavity Ring Down  : ring down time Threshold Laser ON Laser OFF
Laser emission
Ring-down
events
Time
Cavity modes
Frequency
Threshold
Frequency scan
Laser OFF
Laser ON
 : ring down time

6. Cavity Ring Down L R R R= 0.99995  0 ~100 µs - Empty cell t0
Laser
Out R R
R=  0 ~100 µs
time
Intensity
- Empty cell t0

7. Cavity Ring Down R R R= 0.99995  0 ~100 µs - Empty cell - With gas t
Laser
Out R
losses
R=  0 ~100 µs
time
Intensity
- Empty cell t
- With gas t0

8. Experimental CRDS setup
Tdiode: -10°C – 60°C (~ 35 cm-1)
Spectral sampling: 2×10-3 cm-1
80 DFB laser diodes
6nm/diode
Large spectral coverage
5850 – 8330 cm-1 ( µm)
+ ECDL

9. An ultra-sensitive technique…
Typical noise level in routine: min~5×10-11 cm-1
2% light attenuation
(~ km)
S = 1.5 ×10-31 cm/molec
min=5 ×10-13 cm-1
Kassi and Campargue, JCP (2012) 9

10. … with a high dynamics
Dynamics >
4 orders of magnitude

11. An improved line list for water in the 5850-7920 cm-1 region
In coll. with S. Mikhailenko
(IAO-Tomsk)

12. Fit of the recorded CRDS spectra
A Voigt profile is used for each observed lines.
10 Torr
→ List of empirical positions and intensities
+ vibration-rotation assignments (V1 V2 V3 J Ka Kc)

13. Origin of the data in our line list
M11: Mikhailenko et al, JMS 2011 L12: Leshchishina et al, JQSRT 2012
L13: Leshchishina et al, JQSRT 2013
Toth
CRDS Data
Calculated Data

14. Overview comparison with HITRAN2012
This work: lines (for the four main isotopologues)
HITRAN: lines
Difference mainly due to HD16O
→ Important limitation in the transparency windows
+1372 HD18O lines
HD17O lines

15. Some deficiencies in HITRAN2012
On positions…
…and intensities

16. Adopted for the next edition of the GEISA database
Summary
Complete: transitions for the 6 major isotopologues (cut-off of 1×10-29 cm/molecule).
Empirical: positions rely on exp. determined energy levels.
Evidence of some deficiencies in HITRAN2012: lack of HDO lines + some inaccurate pos. and intensities.
Adopted for the next edition of the GEISA database

17. Improvements on line position accuracy
Typ. accuracy: 30 MHz
(1x10-3 cm-1) obtained
with wavemeters
With a frequency comb
(On fly measurements of beat note between DFB and comb teeth)
Accuracy:
< 500 kHz (without aver.)
~10 kHz (with aver.)
In collab. with Politecnico di Milano

18. Campargue, S. Kassi, S. Mikhailenko,
Many thanks to…
Campargue, S. Kassi, S. Mikhailenko,
O. Leshchishina
And LIA SAMIA