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Earth Radiation Budget (ERB) : CERES Calibration Status
Kory J. PriestleyDenise Cooper, Susan Thomas, Grant Matthews, Phil Hess,
Peter Szewczyk, Dale Walikainen, Robert Wilson
Achieving Satellite Intercalibration for Climate ChangeThe National Conference Center
Lansdowne, VAMay 16-18, 2006
NASA Langley Research Center / Science Directorate
Instrument Working GroupWebpage Development
http://asd-www.larc.nasa.gov/Instrument/
NASA Langley Research Center / Science Directorate
• Design is based upon the Earth Radiation Budget Experiment (ERBE) philosophy
• Instrument was designed, manufactured and tested by TRW (Redondo Beach, CA)
• Contains three sensor assemblies with cassegrain optics and thermistor bolometer detectors
• Sensors measure thermal radiation in the near-visible through far-infrared spectral region
• Three sensor channels are coaligned and mounted on a spindle which rotates about the elevation axis
• Hemispherical sampling obtained with an azimuthal axis 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…
Spacecraft Instruments LaunchScience Initiation
Collected Data
(Months)
TRMM PFM 11/97 1/98 9
Terra FM1, FM2 12/99 3/00 76 +
Aqua FM3, FM4 5/02 6/02 46 +
? FM5 ? ? ?
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…
Spacecraft Instruments LaunchScience Initiation
Collected Data
(Months)
TRMM PFM 11/97 1/98 9
Terra FM1, FM2 12/99 3/00 76 +
Aqua FM3, FM4 5/02 6/02 46 +
? FM5 ? ? ?
20.3 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)
Re
sp
on
siv
ity (
-)
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
Spectral Regions
Solar TerrestrialAtmospheric
Window
Wavelengths 0.3 - 5.0 m 5.0 - 200 m 8 - 12 m
Scene levels <100 w/m2-sr >100 w/m2-sr <100 w/m2-sr >100 w/m2-sr All Levels
Accuracy Requirements
0.8 w/m2-sr 1.0 % 0.8 w/m2-sr 0.5 % 0.3 w/m2-sr
Stability Requirements
< 0.14%/yr < 0.1%/yr
Climate
Stability Goals
< 0.6 w/m2/dec
< 0.06 %/yr
< 0.2 w/m2/dec
< 0.02%/yr
Radiometric Performance Requirements
5-Year CERES Mission Lifetime
NASA Langley Research Center / Science Directorate
BDS and ERBE-Like Release Strategy
Edition1 - Static Algorithms and coefficients - baseline product used in cal/val protocol
Edition2 - Utilizes temporally varying coefficients to correct for traceable radiometric drift. All spectral changes are broadband and
‘gray’.
Edition3 - Release date Fall 2006. 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 the release of the next Edition.
Edition2 products lag Edition1 by a minimum of 4 months
NASA Langley Research Center / Science Directorate
Notification of Revision
CERES BDS (BiDirectional Scan) Terra Edition2 Data 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 document briefly summarizes key validation results, provides cautions where users might easily misinterpret the data, provides links to further information about the data product, algorithms, and accuracy, gives information about planned data improvements. This document also automates 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 strongly suggested that authors, researchers, and reviewers of research papers re-check this document for the latest status before publication of any scientific 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
Terra ES-8 Edition2_Rev1 Summary
•Cal/Val Protocol demonstrates radiometric stability of the data products through 11/2004 of….
Edition1 Edition2 Edition2_Rev1
FM1 FM2 FM1 FM2 FM1 FM2
LWday .3 .6 .125 .125 .125 .125
LWnight .1 .125 <.1 <.1 <.1 <.1
SW .2 .4 .2 .3 .1 .1
WN <.1 <.1 <.1 <.1 <.1 <.1
Note: Values apply to all-sky global averages Units are in %/yr
NASA Langley Research Center / Science Directorate
ProductSpatial
Scale
Temporal
ScaleMetric
Spectral
Band
Internal BBFiltered
RadianceN/A N/A Absolute Stability TOT, WN
On-Board Internal LampFiltered
RadianceN/A N/A Absolute Stability SW
SolarFiltered
RadianceN/A N/A Relative Stability TOT, SW
Theoretical Line-by-LineFiltered
Radiance> 20 Km Instantaneous
Inter-Channel
Theoretical AgreementTOT, WN
Unfiltering Algorithm Theoretical Validation
N/A N/A N/A N/A TOT, SW, WN
Inter-satellite
(Direct Comparison)Unfiltered Radiance
1-deg Grid 1 per crossingInter-Instrument
Agreement, StabilityTOT, SW, WN
VicariousGlobally Matched Pixels
(Direct Comparison)Unfiltered Radiance
Pixel to Pixel DailyInter-Instrument
AgreementTOT, SW, WN
Tropical Mean
(Geographical Average)Unfiltered Radiance
20N – 20S MonthlyInter-Channel
Agreement, StabilityTOT, WN
DCC AlbedoUnfiltered Radiance
>40 Km MonthlyInter-Instrument
agreement, StabilitySW
DCC 3-channelUnfiltered Radiance
>100 Km MonthlyInter-Channel
consistency, stabilityTOT, SW
TIme Space Averaging Fluxes Global MonthlyInter-Instrument
AgreementLW, SW
Lunar Radiance Measurements
Filtered Radiance
Sub Pixel QuarterlyInter-Instrument
AgreementLW, SW, WN
CERES Instrument Radiometric Validation Activities
NASA Langley Research Center / Science Directorate
CERES Onboard Calibration Philosophy
PRT PRT SUN Monitor Diode
ICSBB MAM SWICS
Window Sensor
TotalSensor
Shortwave Sensor
Field-of-ViewCoalignment
Traceability
Sources
RadiometricChannel
ValidationStudies
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 Calibration measurements into orbit
Mirror Attenuator Mosaic (MAM)
• Solar Diffuser plate attenuates direct solar view (~5800K Spectrum)
• MAM is a Nickel substrate with Aluminum coated spherical cavities or divots
• Provides a Relative calibration of the Shortwave channel and the SW portion of the Total channel
• Designed to provide a long-term on-orbit SW calibration source.
• Solar Cal results to date are suspect due to large initial drift in MAM surface reflectances…
NASA Langley Research Center / Science Directorate
CERES Solar Calibration Results
-2
-1
0
1
2
3
4
5
6
7
May-02 Nov-02 May-03 Nov-03 May-04 Nov-04
Date
Se
ns
or
Re
sp
on
se
, Pe
rce
nta
ge
Ch
an
ge
FM3 SW FM3 TOT
-2
-1
0
1
2
3
4
5
6
7
May-02 Nov-02 May-03 Nov-03 May-04 Nov-04
Date
Se
ns
or
Re
sp
on
se
, Pe
rce
nta
ge
Ch
an
ge
FM4 SW FM4 TOT
-2
-1
0
1
2
3
4
5
6
7
Feb-00 Aug-00 Feb-01 Aug-01 Feb-02 Aug-02 Feb-03 Aug-03 Feb-04 Aug-04
Date
Se
ns
or
Re
sp
on
se
, Pe
rce
nta
ge
Ch
an
ge
FM1 SW FM1 TOT
-2
-1
0
1
2
3
4
5
6
7
Feb-00 Aug-00 Feb-01 Aug-01 Feb-02 Aug-02 Feb-03 Aug-03 Feb-04 Aug-04
Date
Se
ns
or
Re
sp
on
se
, Pe
rce
nta
ge
Ch
an
ge
FM2 SW FM2 TOT
NASA Langley Research Center / Science Directorate
Terra SW Internal Calibration ResultsFM1 In-Flight Internal Calibration Results
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
2/1/00
6/1/00
10/1/
00
2/1/01
6/1/01
10/1/
01
2/1/02
6/1/02
10/1/
02
2/1/03
6/1/03
10/1/
03
2/1/04
6/1/04
10/1/
04
2/1/05
6/1/05
Date
Sen
sor
Res
po
nse
Ch
ang
e, P
erce
nt
SW-L1 SW-L2 SW-L3
Normalized to Start of Mission
FM2 In-Flight Internal Calibration Results
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
2/1/00
6/1/00
10/1/
00
2/1/01
6/1/01
10/1/
01
2/1/02
6/1/02
10/1/
02
2/1/03
6/1/03
10/1/
03
2/1/04
6/1/04
10/1/
04
2/1/05
6/1/05
Date
Sen
sor
Res
po
nse
Ch
ang
e, P
erce
nt
SW-L1 SW-L2 SW-L3
Normalized to Start of Mission
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 4
Wavelength (micron)
0 1 2 3 4
Wavelength (micron)
Sp
ectr
al R
esp
on
se,
N
orm
aliz
ed R
adia
nce
1.0
0.8
0.6
0.4
0.2
0.0
NASA Langley Research Center / Science Directorate
LEO Missions Subject to Spectral Darkening
Bandpasses of Selected Instruments
0
1
2
3
4
5
6
7
8
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Wavelength (Microns)
Ind
ex
Modis SeaWifs LandSat7 Toms SORCE-SIM SORCE SOLSTICE GOME
NASA Langley Research Center / Science Directorate
Spectral Darkening on Similar Missions
Global Ozone Monitoring Experiment (GOME) Spectral Darkening
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Wavelength/Radiometric Channel (um)
Rela
tive R
esp
on
se
1996
1997
1998
1999
2000
2001
NASA Langley Research Center / Science DirectoratePage 21
SD degradation (accumulated at a 6-month period) as a function of wavelength
Faster degradation rate after fixing the SD door at “open position”
Yr 1
Yr 2
Yr 3
Yr 4
Yr 5
Modis Solar Diffuser Spectral Degradation
NASA Langley Research Center / Science Directorate
Direct Comparison of Nadir Radiance Measurements
Two CERES instruments on a common platform allows for a unique validation 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 (t < 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
1.015
1.010
1.005
1.000
0.995
0.990
0.985
0.980Mar-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
1.015
1.010
1.005
1.000
0.995
0.990
0.985
0.980Mar-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
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
1.02
1.03
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
CERES Onboard Calibration Philosophy
PRT PRT SUN Monitor Diode
ICSBB MAM SWICS
Window Sensor
TotalSensor
Shortwave Sensor
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
Window Sensor
TotalSensor
Shortwave Sensor
Field-of-ViewCoalignment
Traceability
Sources
RadiometricChannel
ValidationStudies
Albedo
Moon
NASA Langley Research Center / Science Directorate
DCCalb = frad(ed1cv)*{flx(ssf)/ufrad(ssf)} * DM(sz)/Fs
0.54
0.55
0.56
0.57
Mar-00 Sep-00 Mar-01 Sep-01 Mar-02 Sep-02 Mar-03 Sep-03 Mar-04 Sep-04 Mar-05
Date
Fil
tere
d A
lbed
o (
-)
FM1 FM2
Terra Deep Convective Cloud Filtered Albedo
NASA Langley Research Center / Science Directorate
Validation of Pointing Knowledge Using Lunar Radiances
Objective: Utilize the full moon as a quasi-point source to complete a near steady-state raster scan across the CERES FOV.
Goals
•Validate pre-launch alignment measurements
•Measure inter-channel relative pointing accuracy
•Map out spatial non-uniformities in the CERES Optics/Detectors
•This type of mapping is not performed under vacuum prior to launch.
By combining knowledge of the motion of the moon relative to the spacecraft and the programmability of the the CERES Instruments we obtain……..
NASA Langley Research Center / Science Directorate
Elevation
8-degt = 1 min
13-degt = 3 min
18-degt = 5 min
Spaceclamp
7.1° 1° 1.5°1.3° 1.3°1°
Azimuth
Lunar Track
CERES Lunar ScanningExperimental Design
NASA Langley Research Center / Science Directorate
Lunar Scanning Results – CERES Optical Transfer Function
Monte-Carlo Ray Trace(FELIX)
FM-1 Total
FM-1 Shortwave
FM-1 Window
NASA Langley Research Center / Science Directorate
Terra ES-8 Edition2_Rev1 Summary
•Cal/Val Protocol demonstrates radiometric stability of the data products through 11/2004 of….
Edition1 Edition2 Edition2_Rev1
FM1 FM2 FM1 FM2 FM1 FM2
LWday .3 .6 .125 .125 .125 .125
LWnight .1 .125 <.1 <.1 <.1 <.1
SW .2 .4 .2 .3 .1 .1
WN <.1 <.1 <.1 <.1 <.1 <.1
Note: Values apply to all-sky global averages Units are in %/yr
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