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Joep Loos , Manfred Birk, Georg Wagner

New multispectrum fitting software used at DLR for analysis of laboratory Fourier-Transform molecular spectra. Joep Loos , Manfred Birk, Georg Wagner German Aerospace Center , Remote Sensing Technology Institute. Absorption cross sections or line-by-line data?. H igh measurement effort

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Joep Loos , Manfred Birk, Georg Wagner

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  1. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 New multispectrum fitting software used at DLRfor analysis of laboratory Fourier-Transform molecular spectra Joep Loos, Manfred Birk, Georg Wagner German Aerospace Center, Remote Sensing Technology Institute

  2. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 Absorption cross sections or line-by-line data? • High measurementeffort • Higher resolutionnecessary • Low analysiseffort • Onlyinterpolation •  e.g. HFCs, CFCs • Baseline lesscritical • Lessmeasurementsneeded • Extrapolation possible (tosomeextent) • Low linedensity • Error parametrizationaccessible •  e.g. CO, NO, H2O

  3. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 Whymultispectralfitting? „Classical“ analysis: singlespectrumfitting FitMAS, LINEFIT, toolby MB/GW, … Multispectralanalysis • Computationally extensive • Quality assessmentdifficult: onlyspectralresiduals • Data reductionmodelhastobeknown • decorrelatesvariousparameters • opaqueandblendedlinescanbefitted • Computationallyinexpensive • Quality assessmentaccessible: •  Chi-Test, filecuts • Test ofdatareductionmodelpossible • Error covariances lost

  4. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 Multispectrumvssinglespectrumfitting • 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

  5. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 What can the new software do? Filecut • Line models • Voigt • Speed-dependentVoigt (C. Boone) • Speed-dependentGalatry + LM (F. Hase) • pCqSDHC + LM (Ngo, Tran) • Humlicekby Kuntz & Ruytenfor Boone and Tran • Versatile interactivemode • Choice oflinemodel, fitparameters • ILS, calibrationfactors, baseline, channelling, … • Automaticmode • Microwindow-, spectra-, fitparameterselection (Voigt) • Chi-test ofspectralresiduals • Residuaanalysissimilarto MIPAS/ENVISAT REC analsisbyAnuDudhiaplanned • Single spectrumfitting • Temperature/numberdensity fit • Filecuts(resultsof single-spectra-fits vs. ms-fit) • Identificationofsystematicspectrum-specificerrors • Identification/preventionofcorrelationbetweenfittedparameters • Identificationofsourceofinformation

  6. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 How does it look like?

  7. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 Example: Speed-dependentanalysisof H2O n2 band

  8. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 Example: Speed-dependentanalysisof H2O n2 band • Voigt: w-shapedresidualsfor non-opaquelines • Voigt: line-wingresidualsforopaquelines • Fittedbroadeningparameterssystemitically larger whenfittedwith SDV •  Opaquelinesaremodelledtoonarrow • Influenceofnarrowing larger whenbroadeningparameterlower (higher J)

  9. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 Example: Line mixingof N2O n3 band

  10. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 Example: Line mixingof N2O n3 band

  11. > 13th International HITRAN Conference > J. Loos • New multispectrum fitting software used at DLR > June 24, 2014 Concludingremarks • 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

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