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SCILOV10 FP Meeting SCIAMACHY irradiance validation

SCILOV10 FP Meeting SCIAMACHY irradiance validation. M. Weber and S.No ë l Institute of Environmental Physics (IUP), University of Bremen ( weber@uni-bremen.de ). SCILOV10 FP, Frascati , 26/27 February, 2014. Overview. NOTE:

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SCILOV10 FP Meeting SCIAMACHY irradiance validation

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  1. SCILOV10 FP MeetingSCIAMACHY irradiance validation M. Weber and S.Noël Institute of Environmental Physics (IUP), University of Bremen (weber@uni-bremen.de) SCILOV10 FP, Frascati, 26/27 February, 2014

  2. Overview • NOTE: • comparisonsaredonefor SCIAMACHY data at thebeginningofthemission (changefrompre-flightcondition) • timeseriesinformationavailablefrom SOST web page (degradationmonitoring) http://www.iup.uni-bremen.de/sciamachy/LTM/LTM.html SCIAMACHY calibration Pastvalidationactivities Comparisonof SCIAMACHY V7 and V8 spectral solar irradiance (SSI) with Atlas-3 composite (considered a referencedataset) Recentresults on NIR SSI (controversy)

  3. SCIAMACHY SSI • Correctionstomirrorsurfacepolymerisationandothereffects (degradationcorrection): • WLS correction (Pagaran et al. 2011) Drawback: WLS degradestoo! • m-factorapproach (Bramstedt et al. 2009)  V7 • Optical throughputmodelwithlayercontamination (Krijger et al. 2014)  V8 Drawback, bothassumeconstantsun! • 230-2400 nm, moderateley high spectralresolution (0.2-1.5 nm) • Daily measurementsavailable • Preflight absolute radiometricallycalibrated (TPD-TNO) using FEL lampsand NASA sphere, partially in thermal vacuum (not for all scanangles) • Additional inflightcalibration (Lichtenberg et al. 2006): • Straylight (inner-, intrachannel, spatial) • UV/VIS, Si detector, Ch. 1-5 • memoryeffect • darkcurrent (leakagecurrent, analog offset) • NIR channel, InGaAsdetector, Ch. 6-8 • non-linearity • badanddeadpixels • darkcurrent (large thermal background) • pixel-to-pixel gain • Ice-layer (rapid throughputchanges) decontaminationphases

  4. Atlas-3 Composite SSI (Thuillier et al., 2004) • Composite • 200-400 nm: SSBUV, SUSIM and SOLSPEC data from the ATLAS 1 and 3 (shuttle) missions,and SOLSTICE and SUSIM from UARS • 400-800 nm: SOLSPEC data • > 800 nm SOSP IR data • Spectralresolution: 0.25-0.5 nm

  5. Ballon LPMA/DOAS absolute radiometricallycalibrated Gurlit et al., 2005 LPMA/DOAS at 32 km altitudeaboveAire-sur-l‘adour, Oct. 9, 2003 SSI ratioswithrespecttoKurucz Kitt Peak FTS Keydata update for V6

  6. Pastvalidationactivities SIM/SORCE 250-3000 2003-2010 Harder et al., (2010) • Skupin et al., 2005, Noel et al., 2007, Pagaran et al. 2011 x

  7. Fewexamplesofpastvalidation • Comparisonof V6 with/without WLS correctionwithseveralotherdata (Pagaran et al., 2011) • SCIAdatafrom April 2004 Comparisonof V5 with WLS correctionwith SIM (Noel et al., 2007)

  8. SCIAMACHY SSI V7 versus V8

  9. Comparisonto ATLAS-3 composite

  10. Conclusionand Outlook SCIAMACHY agreestowithin 3% with Atlas-3 in thevisible (verysimilarto V7 andearliercomparisons) SCIAMACHY in V7 and V8 underestimate ATLAS-3 in the UV (3-10%), differencesincreasetowardslowerwavelengths SCIAMACHY V8 improves in theoverlapregionsCh. 3/4 and 4/5 andnear 350 nm, but also producesfeatures (near 850 nm, > 1500 nm) both m-factors (Bramstedt et al., 2009) andopticalthroughputmodel (Krijger et al. 2014) do not accountfornatural solar variability(solar cycle, 27-day solar rotation) whichisprobably ok fortrace gas andcloud/aerosolatmosphericretrievals

  11. Recommendations Still someissueswith NIR channels in V8 (quick icing a problem, 850 nm)  needsfurtherevaluation Specific solar dataproductsforspaceand solar sciencecommunities (noremovalsofnaturalvariability) in additionto V8 data Improvingdegradation (opticalthroughputmodel) byallowingfornatural SSI variability (EU Solid, BMBF ROMIC) Correctionsfrompre-flightconditionis still not complete (check on etaloncorrections)

  12. Correction w.r.t preflight Fit range Changesfrompreflight WLS lampcorrection(inflighttopreflight): Improves UV and NIR!

  13. Somehottopics: NIR SSI Bolsee et al., Sol. Phys., 2014 NIR SSI lowerby 8% (>1600 nm) w.r.t. ATLAS-3 and SIM SCIAMACHY in agreementwithgrounddata (IRSPERAD) and ISS SOLAR/SOLSPEC Using WLS correction also goodagreement in Channels 7/8 with SOLAR/SOLSPEC on ISS (Thuillier et al., 2013)

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