CERES Instrument Radiometric Performance · Edition1_CV - Static Algorithms and coefficients -...
Transcript of CERES Instrument Radiometric Performance · Edition1_CV - Static Algorithms and coefficients -...
CERES Instrument Radiometric Performance
Kory J. PriestleySusan Thomas, Denise Cooper, Dale Walikainen,
Phil Hess, Grant Matthews, Peter Szewczyk, Robert Wilson
CERES Science TeamHadley Center
Exeter, UKOctober 25, 2006
NASA Langley Research Center / Science Directorate
• Part 1 - Priestley
• Project status, NGST contract - hardware procurement
• Review performance status
• Present Calibration Plan / Philosophy
• Introduce the concept of contaminant and SW spectral degradation
• Ground based studies to quantify
• On-orbit operations to isolate, quantify
• Part 2 - Matthews
• Review Edition3_beta test runs
• Identify changes incorporated
• Present results
• Identify Edition3 changes for production
Presentation Structure
NASA Langley Research Center / Science Directorate
Instrument Working GroupWebpage Development
http://asd-www.larc.nasa.gov/Instrument/
NASA Langley Research Center / Science Directorate
Current contract with instrument provider (NGST) concludes on 12/31/06
• Ongoing effort to optimize the remaining schedule and $$.
• Final work package(I.e. contract modification) consists of…
- Functional Recalibration of FM-5 (completed 10/10/06)
- Contamination study of spare optical components
- Preliminary investigation of MAM stability improvements
- Repeating key component spectral reflectance measurements
• What to do with FM-5 once contract ends? Options include…
-Establish an additional procurement mechanism
-Hand off to FM-5 to NPOESS IPO
-Ship FM-5 to LaRC for storage and functional testing
CERES Project Status
NASA Langley Research Center / Science Directorate
• Design is based upon the Earth Radiation BudgetExperiment (ERBE) philosophy
• Instrument was designed, manufactured and testedby TRW (Redondo Beach, CA)
• Contains three sensor assemblies with cassegrainoptics and thermistor bolometer detectors
• Sensors measure thermal radiation in the near-visiblethrough far-infrared spectral region
• Three sensor channels are coaligned and mountedon a spindle which rotates about the elevation axis
• Hemispherical sampling obtained with an azimuthalaxis drive system
• Calibration Accuracy Requirements - 0.5% LW, 1.0% SW
CERES Instrument
NASA Langley Research Center / Science Directorate
CERES Terra/Aqua Health & Status
With the exception of the SW channel on the CERES/Aqua FM-4 Instrument,
the CERES Terra/Aqua instruments are functioning nominally…
??2013FM5NPOESS C1
51 +
78 +
9
Collected Data(Months)
6/025/02FM3, FM4Aqua
3/0012/99FM1, FM2Terra
1/9811/97PFMTRMM
ScienceInitiationLaunchInstrumentsSpacecraft
21.5 Instrument Years of Data
NASA Langley Research Center / Science Directorate
Instrument Working GroupWebpage Development
NASA Langley Research Center / Science Directorate
CERES Spectral Response FunctionTRMM/PFM Edition2 Data Products
Note: LWDAY = Total - Shortwave
0.0
0.2
0.4
0.6
0.8
1.0
0.1 1 10 100
Wavelength (Microns)
Resp
on
siv
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-)
Shortwave Total Window
NASA Langley Research Center / Science Directorate
• Requirements for CERES are more stringent than ERBE’s by a factor of 2
• Requirements per Ohring et. al. are more stringent than CERES by a factor of 2-3
< 0.2 w/m2/dec< 0.02%/yr
< 0.6 w/m2/dec< 0.06 %/yr
ClimateStability Goals
< 0.1%/yr< 0.14%/yrStabilityRequirements
0.3 w/m2-sr0.5 %0.8 w/m2-sr1.0 %0.8 w/m2-srAccuracyRequirements
All Levels>100 w/m2-sr<100 w/m2-sr>100 w/m2-sr<100 w/m2-srScene levels
8 - 12 µm5.0 - 200 µm0.3 - 5.0 µmWavelengths
AtmosphericWindowTerrestrialSolarSpectral
Regions
Radiometric Performance Requirements
5-Year CERES Mission Lifetime
NASA Langley Research Center / Science Directorate
Terra ES-8 Data Product Stability Summary
•Cal/Val Protocol demonstrates radiometric stability of the data products through 12/2005 of….
<.1
<.1
<.1
<.1
FM1
Edition3_Beta
<.1
<.1
<.1
<.1
FM2
<.1
.4
.125
.6
FM2
<.1
.2
.1
.3
FM1
Edition1
<.1<.1<.1<.1WN
.1.1.3.2SW
<.1<.1<.1<.1LWnight
.125.125.125.125LWday
FM2FM1FM2FM1
Edition2_Rev1Edition2
Note: Values apply to all-sky global averages Units are in %/yr
NASA Langley Research Center / Science Directorate
Terra ES-8 Data Product Stability Summary
•Cal/Val Protocol demonstrates radiometric stability of the data products through 12/2005 of….
<.1
<.1
<.1
<.1
FM1
Edition3_Beta
<.1
<.1
<.1
<.1
FM2
<.1
.4
.125
.6
FM2
<.1
.2
.1
.3
FM1
Edition1
<.1<.1<.1<.1WN
.1.1.3.2SW
<.1<.1<.1<.1LWnight
.125.125.125.125LWday
FM2FM1FM2FM1
Edition2_Rev1Edition2
Note: Values apply to all-sky global averages Units are in %/yr
NASA Langley Research Center / Science Directorate
Cal-Val Approach / PhilosophyPre-Launch
- Implement a rigorous & thorough ground calibration/characterization program- Cal/Val role must be prominent in original proposal and SOW- System level characterization is typically last test performed prior to delivery of
the instrument- Cost and schedule constraints typically drive programs at that point
Post-Launch- Implement a protocol of independent studies to characterize on-orbit
performance- Studies should cover all spectral, spatial and temporal scales as well as data
product levels- Continuous development of new validation studies- Retain capability to perform ground based characterizations of flight
components (Improved measurement techniques, support anomaly analyses)
Data Product Release Strategy- Develop a logical and well understand approach to data release.- Minimized the number of Editions/Versions of Data- Utilize Data Quality Summaries for the community
NASA Langley Research Center / Science Directorate
On-orbit Cal-Val SequenceThe CERES instrument spectral bands do not correspond directly to
data product spectral bands. For example…
LWday = Total - Short
Therefore we need a logical approach to producing radiometricallyaccurate and stable data products.
In general we approach this in the following order of priority:
1. SW Channel2. Nighttime LW (i.e. Total channel at night)3. Atmospheric WN Channel4. Daytime LW
NASA Langley Research Center / Science Directorate
BDS and ERBE-Like Release Strategy
Edition1_CV - Static Algorithms and coefficients - baseline product used in cal/val protocol, should not be used for scientific studies.
Edition2 - Utilizes temporally varying coefficients to correct for traceable radiometric drift. All spectral changes are broadband and ‘gray’.
Edition3 - Release date Early 2007. Will incorporate temporally varying spectral artifacts in the SW measurements. A complete re-analysis of Ground Calibration with additional component characterization measurements.
User Applied Revisions - Advance capabilities to the users prior to therelease of the next Edition.
Edition2 products lag Edition1 by a minimum of 4 months
NASA Langley Research Center / Science Directorate
Notification of RevisionCERES BDS (BiDirectional Scan) TerraEdition2Data Quality Summary
Investigation: CERESData Product: BiDirectional Scan [BDS]Data Set: Terra (Instruments: FM1, FM2)Data Set Version: Edition2
The purpose of this document is to inform users of the accuracy of this data product as determined by the CERES Team. This documentbriefly summarizes key validation results, provides cautions where users might easily misinterpret the data, provides links to furtherinformation about the data product, algorithms, and accuracy, gives information about planned data improvements. This document alsoautomates registration in order to keep users informed of new validation results, cautions, or improved data sets as they become available.
This document is a high-level summary and represents the minimum information needed by scientific users of this data product. It is stronglysuggested that authors, researchers, and reviewers of research papers re-check this document for the latest status before publication of anyscientific papers using this data product.
Table of Contents•Nature of the BDS Product•Updates to Current Edition•User Applied Revisions•Validation and Quality Assurance•Current Estimated Uncertainty of Data•Cautions When Using Data•Expected Reprocesings•References•Web links to Relevant information•Referencing Data in Journal Articles•Giving Data to Other Users
NASA Langley Research Center / Science Directorate
LW, SW, WNInter-InstrumentAgreementQuarterlySub PixelFiltered
RadianceLunar RadianceMeasurements
TOT, WNInter-ChannelAgreement, StabilityMonthly20N – 20SUnfiltered
RadianceTropical Mean(Geographical Average)
TOT, SW, WNInter-InstrumentAgreementDailyPixel to PixelUnfiltered
RadianceGlobally Matched Pixels(Direct Comparison)
Vicarious
TOT, SW, WNInter-InstrumentAgreement, Stability1 per crossing1-deg GridUnfiltered
RadianceInter-satellite(Direct Comparison)
TOT, SW, WNN/AN/AN/AN/AUnfiltering AlgorithmTheoretical Validation
Inter-InstrumentAgreement
Inter-Channelconsistency, stability
Inter-Instrumentagreement, Stability
Inter-ChannelTheoretical Agreement
Relative Stability
Absolute Stability
Absolute Stability
Metric
LW, SW
TOT, SW
SW
TOT, WN
TOT, SW
SW
TOT, WN
SpectralBand
Instantaneous> 20 KmFiltered
RadianceTheoretical Line-by-Line
Fluxes
UnfilteredRadiance
UnfilteredRadiance
FilteredRadiance
FilteredRadiance
FilteredRadiance
Product
On-Board
TemporalScale
SpatialScale
TIme Space Averaging
DCC 3-channel
DCC Albedo
Solar
Internal Lamp
Internal BB
Global
>100 Km
>40 Km
N/A
N/A
N/A
Monthly
Monthly
Monthly
N/A
N/A
N/A
CERES Instrument Radiometric Validation Activities
NASA Langley Research Center / Science Directorate
CERES Onboard SW Calibration EquipmentShortwave Internal Calibration Source (SWICS)
• Quartz-halogen tungsten lamp (2100, 1900, 1700 K spectrums)
• SiPd independently monitors lamp output
• Design specification is +-0.5% stability over 5-year mission
• Designed primarily to transfer Ground Calibrationmeasurements into orbit
Mirror Attenuator Mosaic (MAM)
• Solar Diffuser plate attenuates direct solar view (~5800KSpectrum)
• MAM is a Nickel substrate with Aluminum coated sphericalcavities or divots
• Provides a Relative calibration of the Shortwave channel andthe SW portion of the Total channel
• Designed to provide a long-term on-orbit SW calibrationsource.
• Solar Cal results to date are suspect due to large initial drift inMAM surface reflectances…
NASA Langley Research Center / Science Directorate
CERES Solar Calibration Results
-2
-1
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May-02 Nov-02 May-03 Nov-03 May-04 Nov-04
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FM3 SW FM3 TOT
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FM4 SW FM4 TOT
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FM1 SW FM1 TOT
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FM2 SW FM2 TOT
NASA Langley Research Center / Science Directorate
Terra SW Internal Calibration ResultsFM1 In-Flight Internal Calibration Results
-0.5
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Date
Sen
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SW-L1 SW-L2 SW-L3
Normalized to Start of Mission
FM2 In-Flight Internal Calibration Results
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SW-L1 SW-L2 SW-L3
Normalized to Start of Mission
NASA Langley Research Center / Science Directorate
CERES Onboard Calibration Philosophy
PRT PRT SUN Monitor Diode
ICSBB MAM SWICS
WindowSensor
TotalSensor
ShortwaveSensor
Field-of-ViewCoalignment
Traceability
Sources
RadiometricChannel
ValidationStudies
NASA Langley Research Center / Science Directorate
CERES Onboard Calibration Philosophy
PRT PRT SUN Monitor Diode
ICSBB DCC SWICS
WindowSensor
TotalSensor
ShortwaveSensor
Field-of-ViewCoalignment
Traceability
Sources
RadiometricChannel
ValidationStudies
NASA Langley Research Center / Science Directorate
CERES SSF Ed2B SW TOA Flux Anomaly
Clear Ocean
Clear Desert
NASA Langley Research Center / Science Directorate
Spectral Degradation : SWICS vs. Earth Spectra
0 1 2 3 4Wavelength (micron)
0 1 2 3 4Wavelength (micron)
Spec
tral
Res
pons
e, N
orm
aliz
ed R
adia
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0.8
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NASA Langley Research Center / Science Directorate
LEO Missions Subject to Spectral DarkeningBandpasses of Selected Instruments
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0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Wavelength (Microns)
In
dex
Modis SeaWifs LandSat7 Toms SORCE-SIM SORCE SOLSTICE GOME
NASA Langley Research Center / Science Directorate
Spectral Darkening on Similar MissionsGlobal Ozone Monitoring Experiment (GOME) Spectral Darkening
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Wavelength/Radiometric Channel (um)
Rela
tive R
esp
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se
1996
1997
1998
1999
2000
2001
NASA Langley Research Center / Science DirectoratePage 26
SD degradation (accumulated at a 6-monthperiod) as a function of wavelength
Faster degradation rate after fixing the SDdoor at “open position”
Yr 1
Yr 2Yr 3
Yr 4
Yr 5
Modis Solar Diffuser Spectral Degradation
NASA Langley Research Center / Science DirectoratePage 27
Preliminary Results of Contamination Study
0.60
0.65
0.70
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1.00
100 1000 10000
Wavelength, Nm
Sp
ectr
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ran
sm
itta
nce
As-Rec'd
As-Dep
UV-Treated
As-D 48-hrs Sun
UV-T 48-hrs Sun
Contamination and UV exposure of spare CERES Quartz filters with Penzane
NASA Langley Research Center / Science Directorate
Direct Comparison of Nadir Radiance Measurements
Two CERES instruments on a common platform allows for a uniquevalidation opportunity…..
Direct Comparison of simultaneous Nadir measurements
Each CERES/Terra instrument views nadir every 3.3 seconds
Thus, we obtain nearly simultaneous measurements of the same geo-location (Δt < 3.3 seconds)….
Spatial, angular, and temporal sampling issues are virtually eliminated.
26,000 co-located (but not independent) measurements in a given day,provides a very rigorous statistical tool.
Results can be discretized by scene type to enhance the analysis.
NASA Langley Research Center / Science Directorate
Terra Edition2 Nadir Direct Comparison
1.005
1.000
0.995
0.990
0.985
1.0151.0101.0051.0000.9950.9900.9850.980
Mar-00 Mar-01 Mar-02 Mar-03 Mar-04
All-Sky
FM1 in Xtrack
FM2 in Xtrack
All-SkyClear OceanSW2
f
SW1f
SW2f
SW1f
SW Nadir Radiances
Mar-00 Mar-01 Mar-02 Mar-03 Mar-04
FM1 in Xtrack
FM1 in RAPS
NASA Langley Research Center / Science Directorate
Terra Edition2 Nadir Direct Comparison
1.005
1.000
0.995
0.990
0.985
1.0151.0101.0051.0000.9950.9900.9850.980
Mar-00 Mar-01 Mar-02 Mar-03 Mar-04
All-Sky
FM1 in XTRACK
FM1 in RAPS
All-SkyClear OceanSW2
f
SW1f
SW2f
SW1f
SW Nadir Radiances
FM1 in Xtrack
FM1 in RAPS
NASA Langley Research Center / Science Directorate
Fixed Azimuth Plane Scanning(FAPS, Xtrack)
Rotating Azimuth Plane Scanning(RAPS)
Primary CERES Operational Modes
NASA Langley Research Center / Science Directorate
RAPS
Whats the difference between RAPS and FAPS?
FAPS
Ground Track
Scan Plane
NASA Langley Research Center / Science Directorate
RAPS
Whats the difference between RAPS and FAPS?
FAPS
NASA Langley Research Center / Science Directorate
RAPS
Whats the difference between RAPS and FAPS?
FAPS
NASA Langley Research Center / Science Directorate
RAPS
Whats the difference between RAPS and FAPS?
FAPS
NASA Langley Research Center / Science Directorate
Edition2_Rev1 Scaling Factor Assumptions
Based upon this understanding, Rev1 scaling factors forSW fluxes were derived.
Explicit assumptions in developing Rev1 factors are:- RAPS instrument does degrades spectrally
- Xtrack instrument does NOT degrade spectrally
- Output of on-board lamps, SWICS, is perfectly stable.
NASA Langley Research Center / Science Directorate
Edition2_Rev1 Scaling Factors
1.00
1.01
1.02
1.03
Mar-00 Mar-01 Mar-02 Mar-03 Mar-04 Mar-05
All Sky Clear Ocean
1.00
1.01
1.02
1.03
Mar-00 Mar-01 Mar-02 Mar-03 Mar-04 Mar-05
All Sky Clear Ocean
1.00
1.01
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Jul-02 Jan-03 Jul-03 Jan-04 Jul-04 Jan-05
All Sky Clear Ocean
1.00
1.01
1.02
1.03
Jul-02 Jan-03 Jul-03 Jan-04 Jul-04 Jan-05
All Sky Clear Ocean
Terra - FM1
Terra - FM2
Aqua - FM3
Aqua - FM4
NASA Langley Research Center / Science Directorate
Application of Edition2_Rev1 Scaling Factors
NASA Langley Research Center / Science Directorate
Instrument Operations to Support CharacterizationIs there evidence of active spectral darkening in crosstrack mode?
Test Platform: Terra
Operational Design: Stow one instrument while operating 2nd in Crosstrackmode.
Metric: Compare matched footprints before and after stow period and testmeans for signifigance.
XtrackXtrack9,10XtrackStow7,8XtrackXtrack5,6StowXtrack3,4
XtrackXtrack1,2FM2FM1Month
NASA Langley Research Center / Science Directorate
Operations to Characterize Spectral Darkening
2006
2005
Year
EliminatedEliminatedNoXtrackNoXtrackApril
EliminatedEliminatedYes9XtrackYes9XtrackMay
EliminatedEliminatedYes9XtrackYes9XtrackJune
EliminatedEliminatedYes9XtrackYes9XtrackJuly
EliminatedEliminatedYes9XtrackYes9XtrackAugust
5. Nighttime internal calibrations, July 1-7, 2000.6. Valencia Over-Flights, September 12-17, 2005.7. Lunar Scans8. Solar Calibrations9. Raster Scan A_Only Azimuth Sync Profiles
Notes:1. Short-Earth scan profile turn-around reduced 80, March 31, 2005 on FM1 and FM2.2. Expanded solar-avoidance region criteria May 13, 2005.3. Greenland Summer Solstice Terra-Aqua Inter-Calibration, June 6- July 6, 20054. GERB Operations, June 9-30, 2005.
EliminatedEliminatedNoXtrackNoStowedFebruary
EliminatedEliminatedNoXtrackNoXtrackMarch
EliminatedEliminatedNoXtrackNoXtrackNovember
EliminatedEliminatedNoXtrackNoXtrackDecember
EliminatedEliminatedNoXtrackNoStowedJanuary 2006
EliminatedEliminatedYes9XtrackYes9XtrackSeptember
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
FM1 SolarCalibrations
No
No
No
No
No
Yes
Yes
Daily
Yes
FM2 SolarCalibrations
Xtrack
Xtrack
Xtrack
Xtrack3,5
Xtrack3
Xtrack
Xtrack
Xtrack
Xtrack
FM1 AzimuthGimbal
EliminatedEliminatedXtrackOctober
EliminatedEliminatedXtrack6September
EliminatedEliminatedStowedAugust
EliminatedEliminatedStowedJuly
EliminatedEliminatedXtrack4June
DarkeningRate Impact
RAM DirectionDirectSolar Exposure
FM2 AzimuthGimbalMonth
NominalNominal7NominalXtrack, AtrackFebruary 2005
Reduced2Eliminated2Rotating, AtrackMay
No ChangeNominalReduced1RotatingApril
No ChangeAccelerated(FM2)8Accelerated (FM2)XtrackMarch
NASA Langley Research Center / Science Directorate
Terra Edition1_CV SW Full Swath Direct Comparison
-1.25
-1.24
-1.23
-1.22
-1.21
-1.20
-1.19
-1.18
6/2/09 8/2/09 10/2/09 12/2/09 2/1/10 4/3/10 6/3/10
100*(FM2-FM1)/FM1
FM2Stowed
FM1Stowed
Is there evidence of active spectral darkening in crosstrack mode?
NASA Langley Research Center / Science Directorate
Side View
Visualization of new operational constraints
Top View
NASA Langley Research Center / Science Directorate
Foggy MAM Contamination Cover
- Subsequent to spacecraft levelthermal vacuum testing, a visualinspection of the FM-3 instrumentrevealed a ‘fog’ on the interiorsurface of the FM-3 MAMcontamination cover.
- Visual inspection of opticsrevealed no visible deposition.
- Testing yielded conflictingopinions of the material, mostlikely candidate was penzanelubricant.
NASA Langley Research Center / Science Directorate
Burnt CERES Aqua Test HeatersPrior to spacecraft level thermalvacuum testing, spacecraftpersonnel overloaded test-onlyheaters on the CERES Aquainstruments.
Heaters were visibly charred anddestroyed. Location is externalto optical chamber and undersilver teflon radiators. Heaterswere removed and area cleanedprior to thermal vac testing.