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