1. > ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor > 2017-06-20
Experimental line list of water vapor absorption lines in the spectral ranges 1850–2280 cm-1 and 2390–4000 cm-1
Joep Loos, Manfred Birk, Georg Wagner
German Aerospace Center (DLR) – Remote Sensing Technology Institute

2. Ground-based remote sensing – H2O spectoscopic database
> ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor >
Ground-based remote sensing – H2O spectoscopic database
Schneider et al. JQSRT 112 (2011)
Karlsruhe (Germany), ground-based solar occultation measurement
Large spectral residuals
Erroneous data products (e.g. water vapor concentration profiles)
Inaccurate line parameter values and insufficient line profile
 Improvement of H2O line parameters in the range 1850 – 4000 cm-1

3. FT-Transmittance measurements at DLR
> ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor >
FT-Transmittance measurements at DLR
High-resolution Fourier transform spectrometer Bruker IFS 125HR
White-type multireflection cell directly attached to the interferometer
Absorption path m
Temperature range K
Continuous flow of sample gas

4. FT-Transmittance measurements at DLR
> ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor >
FT-Transmittance measurements at DLR
0.1 mbar H2O, m, 296 K mbar H2O, m, 296 K
H2O, RT
H2O/air, RT
H2O/Luft, HT/LT
pH2O (mbar)
0.1 – 20
0.2 – 7.5
0.01 – 9.0
ptot (mbar)
30 – 1000
90/100
l (m)
0.219 –
0.249 –
T (K)
296
213 – 350

5. Analysis Multispectrum least squares fitting
> ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor >
Analysis
Multispectrum least squares fitting
HITRAN12 as starting point
qSDHC + Rosenkranz line mixing based on HTP implementation by Tran et al.
Retrieval of line positions, intensities and line shape parameters
Speed-dependence, Dicke-narrowing and line mixing have to be taken into account

6. Statistics for fitted line parameters
> ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor >
Statistics for fitted line parameters
HITRAN DLR
Parameter
Isotopolog s S
g0,s
g2,s
d0,s ns
dT0,s Ys
YsT1
H216O
4016
4002
3323
2678
2574
1884
1276
143 6
1036
1034
739
500
477
253
136 3
622
620
396
241
211
110 48
HDO
1300
1291
841
509
456
204 64 8
6974
6947
5299
3928
3718
2451
1524
154
Parameter
Isotopolog
g0,a
g2,a
d0,a
nVC,a na
dT0,a Ya
YaT1
YaT2
H216O
2655
1690
2268
234
2487
2010
345 6 2
481
167
334 3
406
254 4
218 74
132
180
101
HDO
470 88
140
324
155 S
3824
2019
2984
237
3397
2520
355
1850 – 2280 cm-1 and 2390 – 4000 cm-1
S > 1∙10-26 cm molecule-1
~ 7000 lines
> parameters

7. Line intensities – Comparison to HITRAN12, GEISA15 and ab initio
> ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor >
Line intensities – Comparison to HITRAN12, GEISA15 and ab initio
HITRAN12
GEISA15
ab initio
Ab initio: Birk et al. JQSRT, im Druck (2017), Lodi et al. JCP 128 (2008) , Lodi et al. JCP 135 (2011)

8. Line intensities – Comparison to ab initio
> ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor >
Line intensities – Comparison to ab initio
sexp < 1%
Good agreement for n2-, n3-lines (better than 1% on average)
Large scatter and systematic deviation for n1-lines
Ab initio: Birk et al. JQSRT, im Druck (2017), Lodi et al. JCP 128 (2008) , Lodi et al. JCP 135 (2011)

9. Air-broadening widths and speed-dependence
> ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor >
Air-broadening widths and speed-dependence
Ratio speed-dependence/air broadening g2,0/g0,a almost constant
Air-broadening parameters systematically larger than HITRAN12 values  different line shape model used in analysis

10. Impact on atmospheric retrievals
> ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor >
Impact on atmospheric retrievals
Significant improvement of spectral residuals in comparison to the use of HITRAN12

11. > ISMS 2017 > Joep Loos • P2355: Experimental line list of water vapor > 2017-06-20
Summary
Experimental line parameter list in the spectral ranges 1850 – 2280 and 2390 – 4000 cm-1
Multispectrum analysis of pure H2O and H2O/air-mixture transmittance measurements
Use of quadratic speed-dependent hard collision model + Rosenkranz line mixing
Line intensity range down to cm molecule-1
Use of the new line parameters reduces spectral residuals significantly in atmospheric retrievals
Line parameters included in HITRAN16
Parameter list available
dx.doi.org/ /j.jqsrt
dx.doi.org/ /j.jqsrt