New multispectrum fitting software used at DLRfor analysis of laboratory Fourier-Transform molecular spectraJoep Loos, Manfred Birk, Georg WagnerGerman Aerospace Center, Remote Sensing Technology Institute
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 1
Absorption cross sections or line-by-line data?
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 2
802.5 803.0 803.5 804.0 804.50
200
400
-ln(t)
x T
/ p
Wavenumber/cm-1
293 K 273 K 253 K 233 K 203 K
𝑡=exp [−𝛼 (𝑇 ,𝑃 ,𝜎 ) ∙𝑙 ∙𝑁 ] 𝛼=∑𝑖𝑆𝑖 ∙ 𝑓 (𝑇 ,𝑃 ,𝜎 ,�⃗�𝑖 )
• High measurement effort• Higher resolution necessary• Low analysis effort• Only interpolation
e.g. HFCs, CFCs
• Baseline less critical• Less measurements needed• Extrapolation possible (to some extent)• Low line density• Error parametrization accessible
e.g. CO, NO, H2O
Why multispectral fitting?
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 3
„Classical“ analysis: single spectrum fitting
FitMAS, LINEFIT, tool by MB/GW, …
Multispectral analysis
𝑆 ,𝛾𝐹 ,𝑛
𝑇 𝑖= 𝑓 (𝑆 ,𝛾𝐹 ,𝑛 ,𝑝𝑖 ,𝑇 𝑖 )
𝑆 ,𝛾𝐹 ,𝑛
• Computationally inexpensive• Quality assessment
accessible: Chi-Test, filecuts• Test of data reduction model
possible• Error covariances lost
• Computationally extensive• Quality assessment difficult:
only spectral residuals• Data reduction model has to
be known• decorrelates various
parameters• opaque and blended lines can
be fitted
• Single spectrum fitting + consecutive data reduction = sound method for generation of spectroscopic data
• Complexity and computation time requirements restrict multispectral fit to small spectral intervals
• Temperature and number density fit requires large spectral range restricted to single spectrum fits
• Multispectrum fit yields higher precision in many cases• Multispectrum fit can give higher accuracy in some cases• Multispectrum fit enables fitting of parameters not accessible to single spectral analysis e.g. speed-dependence
Fusion of multispectrum and single spectrum fit to combine advantages
Multispectrum vs single spectrum fitting
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 4
• Line models• Voigt• Speed-dependent Voigt (C. Boone)• Speed-dependent Galatry + LM (F. Hase)• pCqSDHC + LM (Ngo, Tran)• Humlicek by Kuntz & Ruyten for Boone and Tran
• Versatile interactive mode• Choice of line model, fitparameters• ILS, calibration factors, baseline, channelling, …
• Automatic mode• Microwindow-, spectra-, fitparameter selection (Voigt)• Chi-test of spectral residuals• Residua analysis similar to MIPAS/ENVISAT REC analsis
by Anu Dudhia planned
• Single spectrum fitting
• Temperature/number density fit
• Filecuts (results of single-spectra-fits vs. ms-fit)• Identification of systematic spectrum-specific errors
• Identification/prevention of correlation between fitted parameters
• Identification of source of information
What can the new software do?
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 5
cor𝑖𝑗=( 𝐽𝑇𝑊𝐽 )𝑖𝑗
√ ( 𝐽𝑇𝑊𝐽 )𝑖𝑖 ( 𝐽𝑇𝑊𝐽 ) 𝑗𝑗𝐴= ( 𝐽𝑇𝑊𝐽 )− 1 ( 𝐽𝑇𝑊 )
C𝑝 ,𝑠=𝑁 ∙∑𝑖∈ 𝑠
|𝐴𝑝 , 𝑖|
max𝑖 [ 𝐴𝑝 ,𝑖 ]
Filecut
How does it look like?
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 6
Example: Speed-dependent analysis of H2O n2 band
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 7
0,00,20,40,60,81,0
tran
smitta
nce
pure1.2e21 m-2
pure6.1e21 m-2
pure1.1e23 m-2
pure5.2e23 m-2
pure4.3e23 m-2
0,00,20,40,60,81,0
SDV
SDV
SDV
SDV
Voigt
Voigt
tran
smitta
nce
SDV
pure2.1e24 m-2
pure3.0e22 m-2
pure2.5e24 m-2
pure1.0e25 m-2
1000.6 mb2.2e22 m-2
0,00,20,40,60,81,0
tran
smitta
nce
501.8 mb1.1e22 m-2
400.3 mb1.3e24 m-2
399.9 mb2.6e24 m-2
199.4 mb1.1e22 m-2
199.4 mb4.6e22 m-2
0,00,20,40,60,81,0
tran
smitta
nce
residual water 200.7 mb1.0e23 m-2
200.7 mb3.9e23 m-2
200.4 mb1.3e24 m-2
199.6 mb2.6e24 m-2
100.0 mb1.3e24 m-2
0,00,20,40,60,81,0
tran
smitta
nce
100.6 mb2.6e24 m-2
50.4 mb3.9e23 m-2
50.4 mb2.1e24 m-2
pressure- orcolumn density error 50.5 mb
1.3e24 m-249.8 mb
2.5e24 m-2
1287,3 1287,4 1287,5
wavenumber [cm-1]1287,3 1287,4 1287,5
wavenumber [cm-1]1287,3 1287,4 1287,5
wavenumber [cm-1]1287,3 1287,4 1287,5
wavenumber [cm-1]1287,3 1287,4 1287,5
Voigt
Voigt
wavenumber [cm-1]
Voigt
Example: Speed-dependent analysis of H2O n2 band
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 8
0,02 0,04 0,06 0,08 0,100
2
4
6
8 guide to the eye (3rd order polynomial)
( SDV-
Hit1
2) /
Hit1
2 [%
]
Hit12 [cm-1 atm-1]0,02 0,04 0,06 0,08 0,10
0,08
0,12
0,16
0,20
0,24 guide to the eye (3rd order polynomial)
2,SD
V / SD
V
SDV [cm-1 atm-1]
• Voigt: w-shaped residuals for non-opaque lines• Voigt: line-wing residuals for opaque lines• Fitted broadening parameters systemitically larger when fitted with SDV Opaque lines are modelled too narrow• Influence of narrowing larger when broadening parameter lower (higher J)
Example: Line mixing of N2O n3 band
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 9
0,0
0,5
1,0
0.081 %
0.086 %
0.076 %
trans
mitta
nce
103.7 mb, 205.9 mb; 498.2 mb; 1000.2 mb
0.074 %
-0,40,00,4
0.036 %
0.053 %
0.061 %
0.049 %
-0,40,00,4
(obs
- ca
lc) *
100
-0,40,00,4
-0,40,00,4
-0,40,00,4
-0,40,00,4
Voigt - profile:
(obs
- ca
lc) *
100
qSDV+LM - profile:
-0,40,00,4
2190 2200 2210 2220 2230 2240 2250-0,40,00,4
wavenumber (cm-1)
0,0
0,5
1,0
0.081 %
0.086 %
0.076 %
trans
mitta
nce
103.7 mb, 205.9 mb; 498.2 mb; 1000.2 mb
0.074 %
-0,40,00,4
0.036 %
0.053 %
0.061 %
0.049 %
-0,40,00,4
(obs
- ca
lc) *
100
-0,40,00,4
-0,40,00,4
-0,40,00,4
-0,40,00,4
Voigt - profile:
(obs
- ca
lc) *
100
qSDV+LM - profile:
-0,40,00,4
2240,4 2240,8 2241,2 2241,6 2242,0-0,40,00,4
wavenumber (cm-1)
Example: Line mixing of N2O n3 band
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 10
-40 -30 -20 -10 0 10 20 30 40
0,07
0,08
0,09
0,10 qSDV+LM fit to qSDV+LM Voigt
0 (cm
-1at
m-1)
m0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0
0,00
0,01
0,02
0,03
qSDV+LM Voigt
( 0 - 0,
HIT)
/ 0,
HIT
opacity
-40 -30 -20 -10 0 10 20 30 400,004
0,006
0,008
0,010
0,012 qSDV+LM fit
2 (cm
-1 a
tm-1)
m-40 -30 -20 -10 0 10 20 30 40
-0,020-0,015-0,010-0,0050,0000,0050,0100,0150,020
qSDV+LM polyn. fit
Y 0 (at
m-1)
m
• Multispectral analysis essential when using line profiles of high complexity and various parameters
• IDL fitting tool combining advantages of single and multispectrum fit has been developed• Several line models• Interactive and automatic mode• Additional information for quality assessment (parameter correlation matrix, information content, filecuts)
• H2O n2 band reanalyzed• Speed-dependence of broadening parameter has to be considered• Opaque and non-opaque lines fitted simultaneously• Systematically larger broadening parameters than HITRAN
• N2O n3 band• High SNR measurements• Speed-dependence and line mixing have to be considered
Concluding remarks
> 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014DLR.de • Chart 11
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