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Status on SSI and Mg II from GOME/SCIAMACHY/GOME-2

Status on SSI and Mg II from GOME/SCIAMACHY/GOME-2. Mark Weber, Wissam Chehade , A sher Riaz Universität Bremen (Mark.Weber@Uni-Bremen.de). IUP Bremen contribution to the SOLID project. EU SOLID Annual Meeting , Orleans, France, 14-17 Oct. 2013 . Content.

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Status on SSI and Mg II from GOME/SCIAMACHY/GOME-2

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  1. Status on SSI and Mg II fromGOME/SCIAMACHY/GOME-2 Mark Weber, WissamChehade, Asher Riaz Universität Bremen (Mark.Weber@Uni-Bremen.de) IUP Bremen contributionto the SOLID project EU SOLID Annual Meeting, Orleans, France, 14-17 Oct. 2013

  2. Content • SSI from SCIAMACHY/GOME/GOME-2 • recentwork on the Mg II index • Outlook on futurework (e.g. EU SOLID) • SOLID database

  3. SCIAMACHY/GOME/GOME-2 SSI GOME/GOME-2 GOME: 1995-2011 SCIAMACHY: 2002-2012 GOME-2A: 2007-present GOME-2B: 2012-present • Daily full solar discmeasurementsusinga diffuser • Radiometricallycalibratedbeforelaunch • Challenges: • instrumentandplatformanomalies • UV radiationdamage (depositsofcomtaminants on opticalsurfaces) SCIAMACHY GOME/-2 • Pagaran et al., 2011a

  4. Solar irradiance measurements by SCIAMACHY • Continuous coverage: 230-1700 nm (GOMEs 230-800 nm) • Spectral resolution: • ~1.5 nm @ >1000nm • 0.2- 0.4 nm @ < 1000 nm • Spectrometer design: double monochromator (predisperser prism and gratings in each channel) • Reticon linear diode array detector GOME/GOME-2 • Pagaran et al., 2011a

  5. SCIAMACHY opticalthroughputmonitoring Ch. 2: 300-400 nm • SCIA: UV opticaldegradationweakerthan GOME/GOME-2 • Icingof NIR detectors /decontaminationbydetectorheating Ch. 7: 1.94-2.04μm

  6. New degradationcorrectionfor SCIAMACHY White Light Source • Frommeasurementsusingvarious solar light and WLS paths in SCIAMACHYand an opticalthroughputmodellayerthicknessesofdecontaminantson mirror/diffuser surfacesarefitted • ASM mirror • ESM mirror • ESM diffuser • WLS internalmirror • takesintoaccountscan angle dependence

  7. Future plans on solar research (beyond SOLID) Project SCIASOL as part of the BMBF Priority ProgrammeROMIC (‘Role of the Middle Atmosphere in Climate’) • Degradation correctionto SCIAMACHY SSI (improveopticalthroughputmodelaccountingfornatural SSI variability) • Recalibrated SSI datasetsfrom GOME/SCIAMACHY/GOME-2 (240-800nm)  Updated datasetsfor EU SOLID • NOTE: GOME, SCIAMACHY, GOME-2 data in the SOLID databaseare still uncorrecteddata!

  8. Somehottopics: NIR SSI • NIR SSI lowerby 8% (>1600 nm) w.r.t. ATLAS-3/SIM •  See talkbyBolsee Bolsee et al., Sol. Phys., revised (underreview)

  9. Mg II indexfromSCIAMACHY/GOME/GOME-2 • Mg II core-to-wingrationear 280 nm • Indicatorforchromosphericactivity • Correlateswellwith UV and EUV SSI changes (Deland andCebula 1993, Viereck et al., 2001) • insensitiveto instrumental degradation (tofirstorder) (Heath & Schlesinger 1986) • compositesavailablefrom multiple sensors (since 1978) • usedfor UV SSI reconstructionanddegradationcorrections GOME F [mW/m2 nm] solar max& min Wavelength (nm)

  10. GOME/SCIAMACHY/GOME-2 MgII time series • Classicaldefinition (H&S 1986): GOME-2 • High resolutiondefinition (emissioncoreresoved): GOME/SCIA

  11. Mg II indextimeseriesdatabase • Data included in thecomposite

  12. Matchingof Mg II indicesforcreatingcomposites • Scalingby linear regressions in overlapping time periods: • x vs y and y vs x (red) andthentakingaverages (blue) • Scalingworksbestif large overlapsexists (e.g. GOME-U/SOLSTICE) • However: GOME quitenoisytowards end ofitslifetime

  13. Correctionsforinhomogeneities • SCIAMACHY(2009/01) and GOME-2A (2009/09) affectedbydecontaminationactivities (detectorheatingfor additional outgassing) • Composite index: • use N16/SBUV2 astransferstandardacross solar minimum • Treatboth GOME-2 and SCIA as separate time seriesbeforeand after decontaminationwhenscaling

  14. Updated composite Mg II index • Unusuallylowactivity in SC 24 • SC24 solar minimumlowerthanbefore? • GOME/SCIA/GOME-2 Mg II indicesandcompositeupdateddaily www.iup.uni-bremen.de/gome >> Solar Activity

  15. Comparisontothenew SORCE Mg II index • Verygoodagreementwith N16 and SOLSTICE B • Drift in Solstice A (a solar apertureproblem) • Solar minimumof SC24 wellcoveredbycurrent Mg II indices, somedifferences after 2011 (agingproblems?, needstobelooked upon again) Snow et al., J. Space Weather Space Clim., submitted

  16. Long-term stabilityof Mg II indexfrom a singleinstrument • Error calculation (verycrude): 275-285 nm

  17. Validation oferrorestimate (GOME-2) • Qualitative goodagreement • Simple errormodelneeds: • SNR near 280 nmfrompreflightconditions • degradationrates (intensityratioswithrespecttomissionstart)

  18. Long-term stabilityof GOME? • Sinceweroughlyaverage 4 irradiancevalues (e.g. wingvalues), weassumeΔW≈ΔI/√4  1/SNR=0.0007/4 • Due toadvanceddegradation larger uncertaintiesat SC24 minimum (2009) • NOTE: erroronlyaccountsforrandomerrors!

  19. IUP-UBR contributionto SOLID • maincontributionto WP2 (irradiancedataexploitation) • Collecting/updating SSI andproxydata SOLID database (Task 2.1)  seenextslides • Update/improve IUP dataproducts (Task 2.1) • Mg II index • Ca II/Mg I/H_alpha,beta,gamma(?),… • Recalibrated GOME/SCIAMACHY/GOME-2A/GOME-2B • assessmentof SSI & proxydata erroranalysis incl. long-term stability (Task 2.2) • composite SSI & proxydata (mainly UV)  merging, gapfilling, anderroranalyis (Task 2.5)  seetalkby Scholl • Recommendations on 1) exisiting SSI dataand 2) future SSI missions (Task 2.6)

  20. SOLID SSI & Proxy database Working spacedatabase • http://www.iup.uni-bremen.de/~weber/ssi_database/ • Original data: ascii, binary, … • “Password protected“ • username: ssi_database • password: EUsolid2013 Public datawebsite: • http://projects.pmodwrc.ch/solid/index.php/main-database • commondataformat: netcdfw/ CF convention • additonaldata, e.g. imagemasks • plottingcapabilities

  21. SSI databasestructure

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