ceres fm1‐fm4 edion3 radiometric calibraon · 2009. 11. 18. · calibraon. susan thomas kory...

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

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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

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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

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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