1 / 18

Improving SO 2 AMFs: Comparison of different approaches P. Hedelt , P. Valks , D. Loyola

Improving SO 2 AMFs: Comparison of different approaches P. Hedelt , P. Valks , D. Loyola Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) Institut für Methodik der Fernerkundung Abteilung Atmosphärenprozesooren First German S5P Verification Meeting, Bremen 28-29. November 2013.

ivy
Download Presentation

Improving SO 2 AMFs: Comparison of different approaches P. Hedelt , P. Valks , D. Loyola

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Improving SO2 AMFs:Comparisonof different approaches P. Hedelt, P. Valks, D. Loyola Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) Institut für Methodik der Fernerkundung Abteilung Atmosphärenprozesooren First German S5P Verification Meeting, Bremen 28-29. November 2013

  2. Overview • Prototype Algorithm: • Fitting windows: • 312-326nm • 325-335nm (VCD>40 DU) • 360-390nm (VCD>250DU) • Single Wavelength AMF • VerificationAlgorithm: • Fitting windows • 312-324nm • 326.5-335nm (VCD>40 DU) • AMF: Different Approaches • The SO2amountandplumeheightisunknownatthe time ofthemeasurement • Directfittingcomputationaltoo expensive

  3. Currentaproach:Classical DOAS approach • Current GOME-2 SO2 approach • DOAS fit ofmeasuredspectra SO2 SCD • Single-wavelength AMF • Viewing & surface/cloudconditions • Fixed SO2profile (Gaussianat 2.5, 6 and 15km) • SO2 VCD assumedfor AMF: • Standard fittingwindow: 3 DU • VCDs underestimated > 25 DU! • VCD=SCD/AMF • Approach independentofmeasured SO2 SCD

  4. Currentaproach:Classical DOAS approach • Current GOME-2 SO2 approach • DOAS fit ofmeasuredspectra SO2 SCD • Single-wavelength AMF • Viewing & surface/cloudconditions • Fixed SO2profile (Gaussianat 2.5, 6 and 15km) • SO2 VCD assumedfor AMF: • Standard fittingwindow: 3 DU • VCDs underestimated > 25 DU! • Alternative fittingwindow (>40 DU): 100 DU • Currentlyunderinvestigation • VCD=SCD/AMF • Approach independentofmeasured SO2 SCD

  5. Improvedapproach:Iterative AMF approach • Approach based on GOME-2 O3retrieval • DOAS fit ofmeasuredspectra SO2 SCD • Single-wavelengthAMF • Viewing& surface/cloudconditions • Fixed SO2profile(Gaussianat 2.5, 6 and 15km) • Calculationof AMF in iterative way • Determine VCD frominitial (arbitrary) AMF • Calculatenew AMF • Iterateuntil VCD converges • VCD = SCD/AMF • AMF (partly) depends on measured SO2 SCD

  6. Improvedapproach:Empirical DOAS approach • Approach based on OMI O3 retrieval • DOAS fit ofmeasuredspectra SO2SCD • Creationofsimulatedspectra (312-335nm) • Viewing& surface/cloudconditions • Fixed SO2profile (2,5km FWHM Gaussianat 2.5, 6 and 15km) • Assumingsetof SO2 VCDs • DOAS fit ofsimulatedspectra SCDs forassumed VCDs • Interpolation ofmeasured SCD on retrieved SCD grid  SO2 VCD • VCD depends on measured SCD • Errors in DOAS fit cancel out

  7. ExamplesKasatochi 08-08-2008

  8. ExamplesKasatochi 09-08-2008

  9. ExamplesGrimsvötn 23-05-2011

  10. Current Status • Classical DOAS approach • (GOME-2) LUT readyfor Standard fittingwindow • S5P LUT canbecreatedvery fast • Iterative AMF approach • AMFs arecurrentlycalculated on-line • AMF LUTs for different VCDs canbecreatedfast • Empirical DOAS • (GOME-2) Spectrahavebeencomputedfrom 312-335nm • VCD LUT for different fittingwindowsisready • LUT interpolationunderconstruction • Currentlytestsareperformed • S5P spectragenerationtakeabout 1 month

  11. Physicalparametersof LUTs

  12. Summary & Conclusion • Currentapproach • AMF independentofmeasured SO2 SCD • VCDs areunder/overestimated • Iterative AMF approach • AMF isfitted in iterative way • AMF partlydependent on measured SCD • Better VCDs • Empirical DOAS approach • DOAS fit ofbothmeasured an simulatedspectra • AMF (or VCD) depends on measured SCD • DOAS errorspotentially cancel out • Resultsclosetodirectfittingresults

  13. Thankyouforyourattention!

  14. Summary • Classical DOAS approach: • Single-wavelengthAMF forviewing & surfaceconditions (315 / 327nm) • Independent ofmeasured SO2 SCD • Underestimateshigh SO2 VCDs • Iterative AMF approach • Single-wavelength AMF forviewing & surfaceconditions (315 / 327nm) • Iterative AMF fitting • AMF (partly) depends on SCD • Empirical DOAS approach • DOAS retrievalofsimulatedspectra on pre-defined VCD grid • Interpolation ofmeasured SCD on gridofsimulated SCDs • Dependent on measured SO2 SCD • Errors in DOAS fit cancel out

More Related