Tim Hewison EUMETSAT GRWG Chair Special Issue of the IEEE TGRS on InterCalibration of Satellite Instruments Special Issue of the IEEE TGRS on InterCalibration of Satellite Instruments ID: 759697
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Slide1
Strategy for calibration references
Tim Hewison(EUMETSAT)(GRWG Chair)
Special Issue of the IEEE TGRS on “Inter-Calibration of Satellite Instruments”:
Special Issue of the IEEE TGRS on
“
Inter-Calibration of Satellite Instruments
”
:
Slide2Overview
Update on
Prime
GSICS Corrections
For information
How to select inter-calibration reference instruments
For information
Improving the Moon
As a calibration reference
A case for international collaboration
Recommendation needed!
Slide3Overview
Update on
Prime
GSICS Corrections
For information
How to select inter-calibration reference instruments
For information
Improving the Moon
As a calibration reference
A case for international collaboration
Recommendation needed!
Slide4New
Prime GSICS Corrections
Define one
Primary GSICS ReferenceFor each spectral band/applicationBy consensus agreement within GSICSUse others as Transfer References Blend corrections from all referencesAfter modifying Corrections to Primary GSICS ReferenceEnsures long-term continuityWithout calibration jumpsEnsures Traceability back to single Primary ReferenceSimplifies users’ implementationCould also blend multiple methods?
Slide5Applied by User
Correcting the Corrections and Blending References
Reference-1
(Primary)
Monitored Instrument
GSICS Correction, g
1 Mon1
Reference-2
(Secondary)
GSICS Correction, g2 Mon2
Mon
Ref1
Delta Correction, g1/2 21
Derived by GSICS
Modified
Correction, g
2,1/2
Mon
2
1
Prime GSICS Correction, g
0
Mon
1
-
g̅
+
Slide6Users’ Application of Prime GSICS Correction
Monitored Instrument
Prime GSICS Correction, g
0 Mon1
Mon
Ref1
Slide7Overview
Update on
Prime
GSICS Corrections
For information
How to select inter-calibration reference instruments
For information
Improving the Moon
As a calibration reference
A case for international collaboration
Recommendation needed!
Slide8Reference Instrument Selection/Migration
GSICS products need an inter-calibration reference
Inter-calibration
R
eference is one instrument
Other instruments may be used as transfer references
We need a way to select the reference
From a list of candidates
First question should be: “
Is it suitable at all?
”
Does it meet minimum threshold requirements (availability, coverage, ...)
Started asking
“
How good is it as a Reference?
”
Impact on overall uncertainty
Score scheme
Slide9Example for SEVIRI-IASI IR
OneDrive SpreadsheetAll values for illustration only And subject to changeSome variables more important for different inter-cal productsTimeliness important for NRTCDate range critical for Archive Re-CalibrationAssumed time-stamp is correct!Scheme needs road testing with other References
9
Scoring Scheme for GSICS Re-Analysis Correction for SEVIRI IR Channels
Threshold
Saturation
MetopA/IASI
Unit
Min
Max
Min
Max
Weight
Min
Max
OK?
Perfect
Score
Date Range
Year
2013
2013
2006
2030
90
2007
2020
Pass
54%
48.8
Geographic Coverage: Lat
deg
-10
10
-90
90
2
-90
90
Pass
100%
2.0
Geographic Coverage: Lon
deg
-10
10
-180
180
2
-180
180
Pass
100%
2.0
Dynamic Range
K
270
300
180
330
5
180
310
Pass
87%
4.3
Spectral Range
cm-1
746
2564
650
2800
10
645
2760
Pass
98%
9.8
Geometric Range: VZA
deg
5
15
0
90
2
0.5
55
Pass
61%
1.2
Geometric Range: VAA
deg
0
Pass
0.0
Geometric Range: SZA
deg
0
Pass
0.0
Geometric Range: SAA
deg
0
Pass
0.0
Geometric Range: Pol
deg
0
Pass
0.0
Diurnal Coverage
hr
9
10
0
12
20
7.8
11.2
Pass
28%
5.6
Field of View
km
300
3
1
12
Pass
100%
1.0
Number of obs/day
/d
0
Pass
0.0
Number of Collocations
/d
1
10000
5
30000
Pass
100%
5.0
Geolocation accuracy
km
10
0.1
10
3.3
Pass
3%
0.3
Polarisation knowledge
deg
Pass
0.0
Radiometric Stability
K/yr
1
0.001
10
0.05
Pass
2%
0.2
Orbital Stability
hr/yr
12
0.1
0
0.001
Pass
100%
0.0
Radiometric Noise
K
10
0.1
1
0.15
Pass
67%
0.7
Uncertainty from SBAF
K
1
0.01
20
0.008
Pass
100%
20.0
Spectral Resolution
cm-1
100
0.5
0
0.25
Pass
100%
0.0
Spectral Stability
cm-1/yr
2
0.01
0
2E-06
Pass
100%
0.0
SBAF Uncertainty
K
1
0.001
10
0.15
Pass
1%
0.1
Absolute Calibration Acc
K
1
0.001
10
0.05
Pass
2%
0.2
Inter-channel calibration
K
2
Pass
0.0
Data Availability
1
1
Pass
Documentation
1
1
Pass
Community adoption
1
1
Pass
Traceability
1
0
Fail
Total
200.0
96%
51%
101.1
Slide10Expanding WMO OSCAR Capabilities
WMO
OSCAR
Observing Systems Capability Analysis and Review Tool
Adding Landing Pages with links to:
Instrument Specifications, Calibration Events, Data Outages, Instrument Monitoring
WMO expanding OSCAR
automatically assess instruments’ capability to address requirements
Based on pre-defined Expert Rules
Could be used to assess GSICS References
Action: Manik to interact with
Jérôme
to push forward the development of the expert system as a tool to select inter-calibration reference instruments
Slide11GSICS - New Delhi- OSCAR 16-20/03/2015
Instrument
view
11
Slide12Overview
Update on
Prime
GSICS Corrections
For information
How to select inter-calibration reference instruments
For information
Improving the Moon
As a calibration reference
A case for international collaboration
Recommendation needed!
Slide13Lunar Calibration Workshop
Participants in the Lunar Calibration
Workshop
Hosted
at EUMETSAT, 1-4 Dec 2014
Organised by EUMETSAT in collaboration with USGS, CNES, NASAAlmost 30 people from 14 different agencies and departments attending (physically or remotely) GSICS / CEOS-IVOSAll participants used GSICS Implementation of ROLO model (GIRO) developed at EUMETSAT in collaboration with T. Stone (USGS)To develop inter-calibration algorithm, need accurate oversampling factors difficulty encountered by all participantsMajor outcomes:the calibration community agreed the GIRO to be the international reference for lunar calibration, traceable to the ROLO model from USGSEstablishment of a Lunar Observation DatabaseRecommend investigating possible funding to establish infrastructure to traceable lunar observations
A GIRO usage policy and a data policy will be defined in collaboration with the participants
USGS expected to have a new version of the ROLO by the end of 2015 updated GIRO by mid-2016
All participants agreed about the need to
organise
another
Lunar Calibration Workshop
(~1 year time)
Slide14TeamSatelliteSensorG/LDatesNumber of Obs (GSICS dataset)Phase angle range (°)CMAFY-3CMERSILEO2013-20149[43 57]CMAFY-2DVISSRGEO2007-2014CMAFY-2EVISSRGEO2010-2014CMAFY-2FVISSRGEO2012-2014JMAMTSAT-2IMAGERGEO2010-201362[-138,147]JMAGMS5VISSRGEO1995-200350[-94,96]JMAHimawari-8AHIGEO2014--EUMETSATMSG1SEVIRIGEO2003-2014380/43[-150,152]EUMETSATMSG2SEVIRIGEO2006-2014312/54[-147,150]EUMETSATMSG3SEVIRIGEO2013-201445/7[-144,143]EUMETSATMET7MVIRIGEO1998-2014128[-147,144]CNESPleiades-1APHRLEO201210[+/-40]CNESPleiades-1BPHRLEO2013-201410[+/-40]NASA-MODISTerraMODISLEO2000-2014136[54,56]NASA-MODISAquaMODISLEO2002-2014117[-54,-56]NASA-VIIRSNPPVIIRSLEO2012-201420[50,52] NASA-OBPGSeaStarSeaWiFSLEO1997-2010204(<10 , [27-66])NASA/USGSLandsat-8OLILEO2013-20143[-7]NASAOCO-2OCOLEO2014NOAA-STARNPPVIIRSLEO2011-201419[-52,-50]NOAAGOES-10IMAGERGEO1998-200633[-66, 81]NOAAGOES-11IMAGERGEO2006-200710[-62, 57]NOAAGOES-12IMAGERGEO2003-201049[-83, 66]NOAAGOES-13IMAGERGEO200611NOAAGOES-15IMAGERGEO2012-201328[-52, 69]VITOProba-VVGT-PLEO2013-201425[-7]KMACOMSMIGEO2010-201460AISTTerraASTERLEO1999-20141-27.7ISROOceanSat2OCM-2LEO2009-20142ISROINSAT-3DIMAGERGEO2013-20142
Instruments with lunar observation capabilities, with the minimum number of Moon observations provided to the GSICS Lunar Observation Dataset (GLOD) - more observations may be available.
Instruments
Slide15Examples of Moon observations from participating instruments
Slide1616
LEO (CWL)
GEO (band)
According
to OSCAR
(WMO)
Courtesy B. Fougnie, CNES
Landsat-8
Slide1717
LEO
GEO
Courtesy B. Fougnie, CNES
Landsat-8
Slide1818
LEO
GEO
Courtesy B. Fougnie, CNES
Landsat-8
Slide19Improving the Moon (as a reference)
Where we are:
GSICS Implementation of ROLO (“GIRO”) v1.0.0 now available, validated against ROLO
Starting to compile GSICS Lunar Observations Database (“GLOD”)
Already found significant dependencies in relative biases of Observed-GIRO irradiances
But still good enough to inter-calibrate 0.6
m band to <1% uncertainty (NIR not so good)
Absolute calibration using GIRO limited to 5-10% by original ROLO dataset
Short-term plan:
Develop inter-calibration algorithm
Integrate results with DCCs in new GSICS products
Continue to expand
GSICS Lunar Observations Database (“GLOD”)
Form community consensus on absolute scale of GIRO
Long-term plan:
Tie GIRO to SI-traceable standards
Ideally through long-term campaign of new hyperspectral lunar observations
Slide20Proposal for activities to address inter-calibration using the Moon
In EUMETSAT’s proposal, points to be addressed:
Estimating the over-sampling factor
Drift correction
Estimation of the SBAFs from GIRO and verification of the results.
Establishing an absolute scale for lunar calibration
Medium and long term activities on lunar calibration
Slide21ROLO/GIRO and absolute calibration
KNOWN DEFICIENCIES OF THE CURRENT REFERENCE
SI traceability
Absolute scale uncertainty (5 – 10 % uncertainty in
absolute
irradiance scale)
Residual geometry dependencies
Multi-band spectral coverage
ESTABLISHING THE REQUIREMENTS
Defining potential improvements and requirements on user applications
Independent method to verify that operational visible calibration meets requirements
Support climate applications and past instruments (e.g. no onboard calibration available)
GOAL
Getting absolute uncertainties to under ~1%
Surface stability + predictability of the Moon’s brightness = lunar reflectance model valid for all times
Level of accuracy of 0.5% is achievable
WHAT IS NEEDED?
Need for a
new lunar measurement program (= many years of observations, to characterize the variations of the lunar brightness with phase and librations)
Minimum 3 years to capture the libration dependence within the bounds of its relative effect
(ROLO operated for more than 8 years)
Traceable high-spectral resolution observations over several years with specific measurements to validate the atmospheric correction.
FUNDING: Currently under investigation (inter-agency [international] collaboration?)
Slide22E. Medium and long term activities on lunar calibration
Investigate the possibility to participate to an international consortium to fund dedicated measurement campaigns.
Review planned activities in this area:
CMA: Obtained funding for new ground-based observations from CAS
CNES?
ESA: interest in contributing but no existing mechanism for such an international funding. Further investigations needed.
EUMETSAT: no existing mechanism for international funding but possibility still under investigation. Science Working Group defines users requirements.
ISRO? IMD?
JMA: no possibility for funding
KMA?
NASA: Proposed
ARCSTONE
mission for Earth Venture funding
NOAA?
CEOS/IVOS members: AIST, JAXA, KIOST, VITO?
Slide23Conclusions
Advice of CEOS-WGCV for GSICS:
Develop inter-calibration using current GIRO as soon as possible
Support SI-traceable lunar observations to tie ROLO to absolute scale
Encourage independent reproduction of ROLO observations
Requirements:
System suitable for operational application (source code)
Globally accessible common lunar irradiance
model
Recommendation is sought from GSICS/CGMS:
How to establish international cooperation to establish, operate and process
A campaign of new lunar observations over full range of conditions (>3yr)
Covering full reflected solar band at high spectral resolution (hyperspectral)
Directly traceable to SI standards
Slide24Thank You