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Laboratory For Atmospheric and Space Physics University of Colorado

Boulder, Colorado

TOTAL AND SPECTRAL SOLAR IRRADIANCE SENSOR (TSIS-1)

SCIENCE DATA PRODUCTS GUIDE

Document No. 159520

Approvers List

Prepared By StéphaneBéland,TSIS-1ScienceDataSystemLead,LASP

Approved By PeterPilewskie,TSIS-1LASPPrincipalInvestigator,LASP

Approved By ErikRichard,TSIS-1SIMInstrumentScientist,LASP

Approved By GregKopp,TSIS-1TIMInstrumentScientist,LASP

Approved By BrianBoyle,TSIS-1ProjectManager,LASP

Approved By ChristopherK.Pankratz,LASPDataSystemsManager,LASPConfiguration Management

Rev Change Description By

A Updated uncertainty sections SBeland

TSIS Science Data Products Guide LASP Engineering Division Document No. 159520RevA

Total and Spectral Solar Irradiance Sensor (TSIS-1)

Science Data Products Guide

September,2018

Revision:A

LASPProject1545340

DocumentNo.159520

ContractNNG09HP02C


Preparedby Date: StéphaneBéland

TSIS-1ScienceDataSystemLead,LASPApprovedby Date: PeterPilewskie

TSIS-1LASPPrincipalInvestigator,LASPApprovedby Date: ErikRichard

TSIS-1SIMInstrumentScientist,LASPApprovedby Date: GregKoop

TSIS-1TIMInstrumentScientist,LASPApprovedby Date:

BrianBoyleTSIS-1ProjectManager,LASP

Approvedby Date:

ChrisPankratzLASPDataSystemsManager,LASP


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CCR# CCRDATE

MOD#

MODDATE Description Section

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TABLEOFCONTENTS

1 INTRODUCTION .................................................................................................... 61.1 PurposeandScope.....................................................................................................................................61.2 RelevantDocuments.................................................................................................................................62 DATA PRODUCTS OVERVIEW ................................................................................ 62.1 DataProductDefinition...........................................................................................................................62.2 DataProcessingLevels............................................................................................................................72.3 DataFlow.......................................................................................................................................................73 Level 3 Data Products ........................................................................................... 93.1 TIMProcessing............................................................................................................................................93.2 SIMProcessing.........................................................................................................................................104 DATA ACCESS AND AVAILABILITY ........................................................................ 12

5 DATA FILE FORMAT AND DATA DEFINITIONS ...................................................... 135.1 TIM.................................................................................................................................................................145.2 SIM.................................................................................................................................................................156 DATA RELEASE NOTES ......................................................................................... 16


1 INTRODUCTION 1.1 Purpose and Scope This document describes the Science Data Products for the Total and Spectral SolarIrradianceSensor(TSIS-1)mission.Itdescribesthemission’sdataproductscontentandformatasdeliveredtothescientificcommunity.Thisdocumentisintendedtobeaguidefortheendusersdescribingthedatagenerated,whereandhowtoaccessthedata,aswellasinformationaboutthespecificdatafieldsandfeaturestheyshouldbeawareof.

1.2 Relevant Documents

RelevantdocumentsthatsupportdetailsprovidedinthisScienceDataProductsGuide(SDPG)arelistedinTable1:RelevantDocuments

.DocumentReference Title

TBD Program-LevelRequirementsofthe(TSIS-1)ontheInternationalSpaceStation(ISS)Project

LASPDoc.145520 TSIS-1DataManagementPlan

LASPDoc.110249 TSISInstrumentOperationsConcept

LASPDoc.151430 TSISAlgorithmTheoreticalBasisDocument(ATBD)Table1:RelevantDocuments

2 DATA PRODUCTS OVERVIEW 2.1 Data Product Definition TheTSIS-1projectwillusethedataleveldefinitionsthatareidenticaltothoseusedforboth the SORCE and TCTE projects and are consistent with NASA Earth ScienceconventionsasdescribedintheEarthScienceReferenceHandbook–AguidetoNASA’sEarth Science Program and Earth Observing Satellite Missions [available viahttp://eospso.nasa.gov/publications/56].TheTSIS-1standarddataproductsconsistofthreelevelsofprocessing:Fullresolution,time-referenced data with all calibration information for each instrument (Level 1);Calibrated,sortedTIMandSIMirradiancedata(Level2);Dailyand6-hourlymeanTSIanddailyand12-hourlymeanSSImeasurements(Level3).ThespecificleveldefinitionspertainingtoTSISareshowninError!Referencesourcenotfound..Level0TSISrawdatarecords(RDR)collectedonISSwillbeprocessedintothesehigher-levelsensordatarecords(SDR)asindicatedinthistable.


TIM SIMLevel0(RDR)

Reconstructed,unprocessedTSIS-1andISSancillarydataatfullresolution

Level1(SDR)

UnprocessedTSIS-1dataatfullresolution,time-referencedandsortedbyinstrument(TIM,SIM)accompaniedbyallcorrectionandcalibrationfactorsandattitude/ephemerisparametersrequiredforconvertingtheTIMandSIMdataintophysicalunits

Level2(SDR)

Sorteddataprocessedintophysicalunitswithallapplicableconversionsandcalibrationsapplied

Level3(SDR)

TSIdataaveragedandreportedatadailyand6-hourlytimecadence

SSIdataaveragedontoastandardspectralgridandreportedatadailyand12-hourlyfixedtimecadence

Table2:TSISDataLevelDefinitions

2.2 Data Processing Levels TheTSISScienceDataSystem(TSDS)deliversLevels0,1,2and3totalandspectralsolarirradiancedataproductstotheGESDISConamonthlycadence.FileformatsarechosenforconsistencywithSORCEandTCTEdata,andforcompatibilitywithexistingsystemsandinterfacesatLASPandtheGESDISC.ThefollowingformatswillbeusedforTSIS-1data:

TIM SIMLevel0 RawBinaryLevel1 HDF5/NetCDFLevel2 HDF5/NetCDF HDF5/NetCDFLevel3 ASCII ASCII

Table3:DataFileFormat

TheTSDSonlymakesavailablethefullycalibratedLevel-3dataproducttothesciencecommunityandgeneralpublic. Lower-leveldataproducts (e.g., Level2)havelimitedscientific value due to data gaps and instrument artifacts (which are precluded fromLevel3dataviaqualityflags)andarethereforenotmadepubliclyavailable.Shorttime-rangesofthesedatawill,however,beavailableuponrequestfromtheTSISscienceteamforspecific,well-definedresearchefforts.

2.3 Data Flow TheTSIS-1groundsystemsupportson-orbitoperationsof theTSIS-1 instruments,aswellastheproduction,storage,management,anddisseminationoftheTSISsciencedata


products. The TSIS-1 ground system consists of the functional elements depicted inError!Referencesourcenotfound.1.

Figure1:TSISGroundSystemArchitecture

TheTSIS-1groundsystemelementsinclude:- TSISScienceOperationsCenter(TSOC)-LocatedatLASPinBoulder,Colorado.

Responsible for TSIS-1 instrument mission planning, routine state-of-healthmonitoring,andinstrumentsuitecommanding

- TSIS Science Data Systems (TSDS) - Located at LASP in Boulder, Colorado.Responsibleforinstrumentcalibration,sciencedataprocessinganddataproductgeneration,sciencedatamanagement,datavalidation,publicdatadissemination,anddistributionofdatatotheGESDISC

- EarthObservingSystemDataandInformationSystem(EOSDIS)dataarchiveanddistribution/GoddardEarthScienceDataandInformationServicesCenter(GESDISC)


TheNASAISSgroundsystemelementsinclude:

- NASAISSgroundstations- NASAHuntsvilleOperationsSupportCenter(HOSC)- NASAPOIC-LocatedatNASAMSFC.ThePOICfacilitatesTSIS-1remotepayload

operations by routing TSIS-1 payload commands to the ISS, retrieving andtemporallyarchivingpayloaddataandISSdatasuchasattitudeandephemeris,routinely transmitting stored data to the LASP TSOC, and performingmissioncriticalpayloadhealthandstatusmonitoring.

- NASA GES DISC. Located at NASA GSFC in Greenbelt, MD. The GES DISC isresponsibleforsciencedataarchivinganddistribution.

3 Level 3 Data Products TheLevel3dataconsistofdailyand6-hourlyaveragedtotalsolarirradiance(TSI),anddailyand12-hourlyaveragedspectralsolarirradiance(SSI).TheLevel3SIMdataarebinnedtoapre-definedwavelengthgrid,providingdatainaformatmostfamiliartothescientificcommunity.

Within24hoursofLevel2andcalibrationdataavailability,allinstrumentsciencedataandspacecraftengineeringdataareprocessedtoderiveLevel3sciencedataproductsinstandardgeophysicalunits(Wm-2forTSIandWm-2nm-1forSSI).Thesedataaremadeavailabletothescientificcommunitythroughdatadistributioncenters.3.1 TIM Processing TheprocessingoftheTSIS-1TIMdataisbasedonexistingcode,originallyadaptedfromSORCETIM,nowsharedbytheSORCE,TCTEandTSISmissions.Changesweremadetoaccount for the different telemetry format, the addition of the SPICE software(https://naif.jpl.nasa.gov)forhandlingthecomplexISSandTPSpointing,andtheaddedISSobstructioninformation(ISSPointingOffice).TheproductionofthecalibratedTSIfromTIMrawdatatakesthefollowingprocessingsteps(depictedinFigure2):

1. Unpackhigh-ratesciencetelemetryintoL1Sdatabasetables2. CreateSPICEkernelsforattitudeandephemeriscalculations3. CalculatePreliminaryirradiancecalculations4. DeterminequalityflagbasedonL1telemetry,obstructionreports,instrument

pointing(SPICE)andintermediaryL2values5. Calculatedarkirradianceusingthedarkmodel6. CalculateTIMsolarexposureandinstrumentdegradation7. Calculate1AUcorrectedirradianceusingdarkirradiance,solardistanceand

Dopplercorrection8. Calculatefullycorrectedirradiancewithinstrumentdegradationcorrection9. CalculateTrueEarthcorrectedirradiance


10. CalculateLevel3TotalSolarIrradiance(1AUandTrueEarth)averagesat6-hourlyanddailycadence

11. ArchiveallLevel1-3dataproductsandpublishLevel3dataproducts

Figure2:TSISTIMdataflowforTotalSolarIrradiancecalculations

3.2 SIM Processing TheprocessingoftheTSIS-1SIMdataisbasedonthemeasurementequationprovidedintheATBDandshownintheequationbelow.Theimplementationofthismeasurement


equation in the data processing system leverages the SORCE experiences, but isoptimizedforTSISconsideringthesignificantdifferenceswithSORCESIMinthevariousoperationalmodes(differenttypeofdiodereadoutandESRmeasurements).

where:Aslitistheaperturearea,Tlistheprismtransmission,flistheslitdiffraction,

S(l,ls)isthespectraltransferfunctionandPESR(ls)/òalistheESRopticalpowerand

Iphotodiode(ls)/Rlisthephotodiodeopticalpower(watts).TheproductionofthecalibratedSSIfromSIMrawdatatakesthefollowingprocessingsteps:

1. TelemetryunpackingintoL1Stables2. Wavelengthdetermination/assignment3. CalculateandapplyDarkcounts4. Calculateinstrumentprofile(versusl)5. Calculatedioderesponsivitytemperaturecorrection(versusl)6. Calculate1AUadjustedUncorrectedSSI(versusl)7. Calculatetheprismdegradation(versusl)8. Calculatethediodedegradation(versusl)9. CalculateCorrectedSSI(Level2)10. CalculateLevel3CalibratedDailySSI11. ArchiveandpublishallLevel3dataproduct

TheprocessingoftheESRdatadiffersfromthediodeprocessinginthedeterminationofthephase-detectioncalculationtoobtaintheinitialdatanumbersateachprismpositioncomparedtothePhotoDiodeAcquisitionRate(PDAR)methodusedforthediodes.


Figure3:TSISSIMdataflowforuncorrectedirradiancecalculations

Figure4:TSISSIMdataflowforcalibratedirradiancecalculations

4 DATA ACCESS AND AVAILABILITY TheprimarydataarchivefortheTSIS-1dataislocatedattheGoddardEarthSciences-DataandInformationServicesCenter(GESDISC)wherethedatacanbedownloaded


directly.TheTSDSalsoprovidesaTSIS-missionwebsitewiththeLevel3dataindifferentdownloadformatsaswellasawebinterfacetoplotandinspectthedatawiththeLASPInteractiveSolarIrradianceDatacenter(LISIRD).Table4providesalistofURLsforthesethreesiteswherethedataareavailable.AdditionalReleaseNotesareavailableatthosesitesdescribingdetailedchangestothedataprocessingordataproductswitheachnewrelease.Table5containsalistofthedataproductscharacteristics.Location URL ContentGESDISC https://disc.gsfc.nasa.gov/datasets?keywords=TSIS ArchivedLevel0andscience

productsLASPTSIS http://lasp.colorado.edu/home/tsis/data/ Fullproductdocumentationand

directdownloadsLISIRD http://lasp.colorado.edu/lisird/ SolarirradiancedatafromTSISand

othermissionsviainteractivetoolsandcommoninterfaces

Table4DataAvailabilitySites.

Characteristic TotalSolarIrradiance(TSI) SolarSpectralIrradiance(SSI)

Coverage FullSolardisk FullSolardisk

TemporalCharacteristics 6-HourlyandDaily 12-HourlyandDaily

SpectralCoverage Allwavelengths 200-2400nm

SpectralResolution TotalSolarIrradiance Instrumentandwavelengthdependent,34nmforSIMat2000nm

KeyGeophysicalParameters TotalSolarIrradiance IncomingSolarIrradiance

AbsoluteAccuracy(RelativeStandardUncertainty,1sigma)

0.01%(100partspermillion) Variesperspectralregion,PleaseseeTSISInstrumentOverviewformeasurementobjectivesandtheSSIwebpageforcurrentstatus.

RelativeAccuracy 0.001%(10ppm)peryear Varieswithspectralregion,PleaseseeTSISInstrumentOverviewformeasurementobjectivesandtheSSIwebpageforcurrentstatus.

Table5DataProductCharacteristics

5 DATA FILE FORMAT AND DATA DEFINITIONS TheGESDISCandtheLASPTSISwebsiteprovidetheLevel3dataproductsastextfilescoveringthewholemission.Additionally,theLASPwebsiteprovidesIDL‘save’fileswiththedataintheformofadatastructureandanIDLroutinetoreadthetextfilesintodatastructures.


5.1 TIM TheTIMASCIIfilesavailablefromGESDISCandtheLASPwebsitehavethesamefixedformatdescribedbelow.

DataDefinition Description

nominal_date_yyyymmdd NominalDataTime,YYYYMMD

nominal_date_jdn NominalDataTime,JulianDayNumber

avg_measurement_date_jdn AverageDataTime,JulianDayNumber

std_dev_measurement_date StdevofAverageDataTime,days,1sigma

tsi_1au TotalSolarIrradiance(TSI)at1-AU,W/m^2

instrument_accuracy_1au InstrumentAccuracyin1-AUTSI,W/m^2,1sigma

instrument_precision_1au InstrumentPrecisioninTSIat1-AU,W/m^2,1sigma

solar_standard_deviation_1au SolarStandardDeviationin1-AUTSI,W/m^2,1sigma

measurement_uncertainty_1au TotalUncertaintyinTSIat1-AU,W/m^2,1sigma

tsi_true_earth TotalSolarIrradianceatEarthdistance,W/m^2

instrument_accuracy_true_earth InstrumentAccuracyatEarthdistance,W/m^2,1sigma

instrument_precision_true_earth InstrumentPrecisionatEarthdistance,W/m^2,1sigma

solar_standard_deviation_true_earth SolarStandardDeviationinTSIatEarth,W/m^2,1sigma

measurement_uncertainty_true_earth TotalUncertaintyinTSIatEarthdistance,W/m^2,1sigma

provisional_flag ProvisionalFlag,1=provisionaldata,0=finaldata

Table6:TSISTIMDataDefinition

ThefollowingparagraphsdiscussthefourdifferentuncertaintiesreportedwiththeTSImeasurements.InstrumentUncertaintyreflectstheinstrument'srelativestandarduncertainty(absoluteaccuracy)andincludesallknownuncertaintiesfromground-andspace-basedcalibrationsplusatime-dependentestimateofuncertaintyduetodegradation.Thisvalueiscurrentlyreportedas410ppm,butisexpectedtoberefinedlowerwithnewcalibrationsandon-orbitvalidations.Thisuncertaintyvariesslightlywithmeasuredinstrumenttemperatureandthetimetotheneareston-orbitcalibrations.ThisvalueisusefulwhencomparingdifferentTSIinstrumentsreportingdatafromthesametimerangeonanabsolutescale.InstrumentPrecisionreflectstheTIM'ssensitivitytoachangeinsignal,andisusefulfordeterminingrelativechangesintheTIMTSIduepurelytotheSunovertimescalesoftwomonthsorless(sothatdegradationuncertaintydoesnothaveasignificanteffect).Thisvalueof5ppmisconstant,andindicatestheinstrument'snoiselevel.


High-cadenceLevel2dataareaveraged(viaanun-weightedmean)toproducedailyand6-hourlyaveragedLevel3data.ThestandarddeviationoftheLevel2valuesaveragedtoproduceeachLevel3valueisindicativeofthesolarvariabilityduringthereportedLevel3measurementinterval,andiscalledtheSolarStandardDeviation.Thisuncertaintyredundantlyincludes(butisgenerallymuchlargerthan)theInstrumentPrecision.TheSolarStandardDeviationisusefulforestimatingpotentialvariationsintheTSIwithinthetimerangeofaLevel3datavalue,suchaswhencomparingTIMTSIvalueswithsolarimagesorotherTSIinstrumentsreportingdataatslightlydifferenttimes.MeasurementUncertaintyisthenetuncertaintyofareportedLevel3datavalue,andistherootsumsquareofInstrumentUncertaintyandSolarStandardDeviation.MeasurementUncertaintyisthevaluethatshouldbeusedwhencomparingabsolutescaleTSIdatafromnon-identicaltimeranges.

5.2 SIM TheSIMASCIIfilesavailablefromGESDISCandtheLASPwebsitehavethesamefixformatdescribedinTable7below.

DataDefinition Description

nominal_date_yyyymmdd NominalDataTime,YYYYMMD

nominal_date_jdn NominalDataTime,JulianDayNumber

wavelength Wavelengthatthecenterofthemeasurement,nm

instrument_mode_id InstrumentMode86(UV),85(VIS),84(IR),83(ESR)

data_version DataReleaseversion

irradiance_1AU SolarSpectralIrradianceat1-AUTSI,W/m^2/nm

instrument_uncertainty InstrumentUncertainty,W/m^2/nm,1sigma

measurement_precision MeasurementPrecision,W/m^2/nm,1sigma

measurement_uncertainty TotalUncertainty,W/m^2/nm,1sigma

quality DataQualityFlag:‘0’forgooddata,‘1’indicatesmissingdata,and‘2’indicatesdatahasbeenfilledfromthepreviousday

Table7:TSISSIMDataDefinition

ThefollowingparagraphsdiscussthethreedifferentuncertaintiesreportedwiththeSSImeasurements.


InstrumentUncertaintyisapre-launchmeasureofinstrumentuncertaintywithcontributionsfromcomponentandunit-levelinstrumentlaboratorycharacterizationsandcalibrationswiththefinalend-to-endfullspectrumvalidationofthemeasuredirradiancesagainstaNIST-traceablecryogenicradiometerperformedinLASP’sSpectralRadiometerFacility.MeasurementPrecisionisderivedfromameasureoftheon-orbitvarianceinthescan-to-scanrepeatabilityintheobservedspectralirradiances.Thisvalueisanupperlimitofmeasurementprecision.MeasurementUncertaintyisametricoftheoverallon-orbituncertainty.Ithascontributionsfrominstrumentuncertainty,uncertaintyduetopost-processingofdata(includingcorrectionofinstrumentdegradation),anduncertaintyduetodifferencesbetweenobservedirradiancesforthe3separateSIMchannels.

6 DATA RELEASE NOTES Itisimportantfortheuserofthesedataproductstoreadthereleasenotesassociatedwitheachdataset.Thesewillcontaincriticalinformationrelatedtodataprocessing,dataquality,andpossibledataissuesrelatedtothedataproducts.Thereleasenotesareavailableatthesamesitesasthedata(seeSection4above).