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CERESFM1‐FM4Edi-on3RadiometricCalibra-on
Susan Thomas Kory Priestley, Phillip Hess, Mohan Shankar
Z. Peter Szewczyk, Dale Walikainen Navtidad M-Smith, Norman Loeb
CERES Science Team Meeting Fort Collins, Colorado
November 3, 2009
Edi-on3Studies1. Gain Adjustments
Incorporate all known changes in gain and other calibration coefficients for each instrument based on the on-board calibration results.
2. Beginning of Mission Spectral Response Functions
Reassess the ground calibration data and determine the spectral response function for the Shortwave and the Total sensors.
3. Set the CERES instruments on the same radiometric scale at mission start
Develop the methodology to place all CERES instruments on the same rad. scale.
4. Determine optimal Spectral Response Function to correct for the on-orbit degradation in Shortwave region
Direct comparison approach is used to correct the change in the SW sensors.
Regression on the Day-Night differences of Longwave and Window measurements on each instrument is used to correct for the degradation in the shortwave region of total sensor.
GainAdjustments
Thein‐flightgainchangesweredeterminedusingtheon‐boardBlackbodysourcesandtheSWICS.
Themonthlyvaria-oninthetotalandwindowsensorgainswerereducedwithafivemonthrunningmeanapproach.
TheBlackbodyandSWICScalibra-ondatacollectedduringgroundtes-ngwerereevaluatedandincorporatedforthegroundtoflightchangesinthesensorgains.
CERESFM1GAINCORRECTIONS
In-Flight Gain Adjustment
0.997
0.998
0.999
1.000
1.001
1.002
1.003
1.004
1.005
1.006
1.007
3/00 3/01 3/02 3/03 3/04 3/05 3/06 3/07 3/08 3/09 3/10
Sen
sor
Res
po
nse
Ch
ang
e
TOTAL WN SW
GroundtoFlightSensorResponsechange:
Total Window Shortwave
0.989 1.004 0.995
‐1.1% +0.4% ‐0.5%
CERESFM2GAINCORRECTIONSGroundtoFlightSensorResponseChange:
Total Window Shortwave
0.9888 1.0161 0.9999
‐1.12% +1.61% ‐0.01%
In-Flight Gain Adjustment
0.997
0.998
0.999
1.000
1.001
1.002
1.003
1.004
1.005
1.006
1.007
1.008
3/00 3/01 3/02 3/03 3/04 3/05 3/06 3/07 3/08 3/09 3/10
Sen
sor
Res
po
nse
Ch
ang
e
TOTAL WN SW
AQUA:CERESFM3&FM4GAINCHANGESCERES FM3 In-Flight Gain Corrections
0.990
0.992
0.994
0.996
0.998
1.000
1.002
1.004
1.006
1.008
1.010
7/02 12/02 7/03 12/03 6/04 12/04 6/05 12/05 7/06 12/06 7/07 12/07 6/08 12/08 6/09 12/09
Sen
sor
Res
pons
e C
hang
e
TOTAL WN SW
CERES FM4 In-Flight Gain Corrections
0.990
0.992
0.994
0.996
0.998
1.000
1.002
1.004
1.006
1.008
1.010
7/02 12/02 7/03 12/03 6/04 12/04 6/05 12/05 7/06 12/06 7/07 12/07 6/08 12/08 6/09 12/09
Sen
sor
Res
pons
e C
hang
e
TOTAL WN SW
Edi-on3Studies1. Gain Adjustments
Incorporate all known changes in gain and other calibration coefficients for each instrument based on the on-board calibration results.
2. Beginning of Mission Spectral Response Functions
Reassess the ground calibration data and determine the spectral response function for the Shortwave and the Total sensors.
3. Set the CERES instruments on the same radiometric scale at mission start
Develop the methodology to place all CERES instruments on the same rad. scale.
4. Determine optimal Spectral Response Function to correct for the on-orbit degradation in Shortwave region
Direct comparison approach is used to correct the change in the SW sensors.
Regression on the Day-Night differences of Longwave and Window measurements on each instrument is used to correct for the degradation in the shortwave region of total sensor.
CERESSpectralResponseFunc-onFM1Edi-on2‐StartofMission
-0.2
0
0.2
0.4
0.6
0.8
1
0.1 1 10 100
Sen
so
r R
esp
on
se
Wavelength (microns)
TOTAL SW WINDOW
SpectralResponseFunc-onEvalua-on
Measurementsfromthepre‐launchtestdatawerere‐analyzedtodeterminetheop-malSpectralResponseFunc-on(SRF)forCERESsensors.
SHORTWAVEREGION:Componentmeasurementsre‐evalua-on:Silverdatafromdifferentcoa-ngruns.
Impactofshortwavereferencesource(SWRS)spectralthroughputonband‐passfiltersusedinthedetermina-onofGain/SRF.
LONGWAVEREGION:
TheFourierTransformSpectrometer(FTS)measurementanalysistodeterminetheSRFintheLongwaveregion.
MohanShankar’spresenta-oninADMWGwillgivedetaileddescrip-onofSpectralResponseFunc-ondetermina-on.
CERES FM1 SW Spectral Response Function
0.72
0.74
0.76
0.78
0.80
0.82
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00
Wavelength, microns
Sen
sor
Resp
on
se
Edition3 Edition2
CERES FM2 SW Spectral Response Function
0.72
0.74
0.76
0.78
0.80
0.82
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00
Wavelength, microns
Sen
sor
Resp
on
se
Edition3 Edition2
CERES FM1 & FM2 Total Sensor Spectral Response Functions
-0.2
0
0.2
0.4
0.6
0.8
1
0.1 1 10 100 1000
Wavelength (microns)
Resp
on
se
FM1- Edition 3 FM2- Edition 3 FM1_Ed1CV FM2_Ed1CV
TERRARadianceComparisonEdi-on2andEdi-on3SpectralResponseFunc-on
ALLSKYGlobalFluxResultsforMarch2000basedonERBE‐LikeES‐8product
NADIRdata
FM1 FM2
Edi-on3Wm‐2
Edi-on2Wm‐2
Ed3‐Ed2 Edi-on2Wm‐2
Edi-on3Wm‐2
Ed3–Ed2
LWday 231.77 230 0.77% 231.84 230.95 0.38%
LWnite 224.61 225.28 ‐0.3% 223.63 224.89 ‐0.56%
SW 256.20 253.59 1.03% 255.52 253.48 0.8%
CERES FM3 SW Spectral Response Function
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0 1 2 3 4 5
Wavelength, microns
Sen
sor
Resp
on
se
Edition3_Test Edition2
CERES FM4 SW Spectral Response Function
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0 1 2 3 4 5
Wavelength, microns
Sen
sor
Resp
on
se
Edition3_Test Edition2
AQUA: CERES FM3 & FM4 Total Sensor Spectral Response Functions
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.10 1.00 10.00 100.00 1000.00
Wavelength (microns)
Sen
so
r R
esp
on
se
FM3-Ed3Test FM4-Ed3Test FM3-Ed2 FM4-Ed2
Edi-on3Studies1. Gain Adjustments
Incorporate all known changes in gain and other calibration coefficients for each instrument based on the on-board calibration results.
2. Beginning of Mission Spectral Response Functions
Reassess the ground calibration data and determine the spectral response function for the Shortwave and the Total sensors.
3. Set the CERES instruments on the same radiometric scale at mission start
Develop the methodology to place all CERES instruments on the same rad. scale.
4. Determine optimal Spectral Response Function to correct for the on-orbit degradation in Shortwave region
Direct comparison approach is used to correct the change in the SW sensors.
Regression on the Day-Night differences of Longwave and Window measurements on each instrument is used to correct for the degradation in the shortwave region of total sensor.
PlacementofCERESmeasurementsonsameRadiometricScale
• CERESmeasurementsfrom5differentinstrumentsspan12years(1998‐2009).
TRMM‐PFM:January–August1998,March2000Terra–FM1&FM2:March2000–PresentAqua–FM3&FM4:July2002‐Present
• ThesameradiometricscaleattheBeginningofMissionMarch2000forTerraandJuly2002forAqua
• FM1isselectedtobetheclimateinstrument:– Producesthelongest,con-nuousdataset– Longestincross‐trackmodeofopera-on– Showsthesmallestspectralchangesforthemission– Showsthebestconsistencyforthe3‐channelcomparison– HasbeenusedtocomparewithAQUAsince2002
TesttosetCERESFM1asreference
• DirectcompareofCERESFM1andFM2basedonERBE‐LikeES‐8product– ProposedEdi-on3dataforMarch2000– Comparisonattheunfilteredradiancelevel
• matchedgeometryofmeasurementsforVZA<60°– 1500comparisonregionsfordayornightinonemonth
– Averagingover1°×1°grid– Forallthreechannelsandallscenetypes
ComplementaryTests• DirectcompareofFM1orFM2andPFM:– ThesameapproachasforTerra
• Edi-on2,March2000PFMdata• PFMgeometrymatchedbyFM1orFM2(PAPSmode)
• DeepConvec-veCloud(DCC)SWalbedo– SSFdatawasusedtodefinedeepconvec-veclouds
• DirectcompareofFM1andFM2basedonSSF– ClearOcean(CLRO)andDCCsubsets– Nearnadirmeasurements– Imagerinforma-oninselec-ngmatchedfootprints
• DirectcompareofTerrafootprintsatnadir(ES8)
RequiredshiqsfortheTerraInstrumentsatBeginningofMission
• Directcompareandothertestsshowsa-sfactoryconsistency,andsta-s-callysignificantdifferences(@2sigmalevel)inthe3channels:
• AdjustmentstotheCERESFM2Measurements– Shortwave(SW)shouldberaisedby0.22%– LW_dayshouldbedecreasedby0.05%– LW_nightshouldberaisedby0.4%– Window(WN)shouldberaisedby0.45%
Z.PeterSzewczykpresenta-onintheADMWGwillcovertheintercomparisonstudyindetail.
Edi-on3Calibra-onSummary1. Gain Adjustments
ThegainchangesforTerraInstrumentsfromMarch2000–Dec2004weredeliveredforproduc-on.ThegainsfromJan2005–Mar2009arebeingvalidated.TheradiometricgainchangesfortheAquaInstrumentswerederived.
2. Beginning of Mission Spectral Response Functions
Theevalua-onofSpectralResponseFunc-onsforTerraInstrumentswerecompletedanddelivered.TheBOMSpectralResponseFunc-onsforAquaInstrumentsarecurrentlyundertes-ng.
3. Set the CERES instruments on the same radiometric scale at mission start
CERESFM1instrumentisselectedasthestandardinstrument.ThecomparisonstudiesbetweenFM1andFM2instrumentswerecompleted.Thecorrec-onvaluestobringTerrainstrumentsonthesameradiometricscalewerederived.
Edi-on3Studies1. Gain Adjustments
Incorporate all known changes in gain and other calibration coefficients for each instrument based on the on-board calibration results.
2. Beginning of Mission Spectral Response Functions
Reassess the ground calibration data and determine the spectral response function for the Shortwave and the Total sensors.
3. Set the CERES instruments on the same radiometric scale at mission start
Develop the methodology to place all CERES instruments on the same rad. scale.
4. Determine optimal Spectral Response Function to correct for the on-orbit degradation in Shortwave region
Direct comparison approach is used to correct the change in the SW sensors.
Regression on the Day-Night differences of Longwave and Window measurements on each instrument is used to correct for the degradation in the shortwave region of total sensor.
BACKUPSLIDES
CERES FM2 In-Flight Gain Adjustment
0.997
0.998
0.999
1.000
1.001
1.002
1.003
1.004
1.005
1.006
1.007
1.008
3/00 3/01 3/02 3/03 3/04 3/05 3/06 3/07 3/08 3/09 3/10
Se
ns
or
Re
sp
on
se
Ch
an
ge
TOTAL WN SW Total -Ed2
CERESFM1&FM2ComparisonsResultsbasedonAll‐sky(ES‐8product)
FM2Radiance(Wm‐2)
RadianceDifference(FM2‐FM1)
Difference%change
73.73 0.04 0.05
70.24 ‐0.23 ‐0.4
72.72 ‐0.16 ‐0.22
5.14 ‐0.02 ‐0.47
4.81 ‐0.02 ‐0.47
TRMM–TERRAComparisonsFM1‐PFMResultsforAll‐Skyscene
Unfiltered Radiance
µ FM1
Δµ Δµ %µ
LW_day 85.69 -0.08 -0.10
LW_night 80.98 -0.46 -0.56
SW 73.63 0.20 0.28
FM2‐PFMResultsforAll‐Skyscene
Unfiltered Radiance
µ FM2
Δµ Δµ %µ
LW_day 85.59 -0.04 -0.05
LW_night 80.57 -0.78 -0.97
SW 70.93 -0.24 -0.34
SSFDCCbasedSWAlbedo
TERRAFM1‐FM2Comparison:FM1andFM2albedoresultsfrommatchedfootprintsare0.721and0.720respec-vely.
TRMM–TERRAComparison:PFM,FM1andFM2albedoresultsare0.709,0.705and0.7respec-vely.
FM1ThreeChannelComparison
Day@meNadirslope(fSWvs.DeltaLW)
Edi-on1‐CV ‐0.0208
Edi-on‐3 ‐0.0036
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