1. Activities in the framework of GSICS CNES GPRC Report
GSICS Annual Meeting 4-8th March 2013, Williamsburg, VA
Activities in the framework of GSICS
CNES GPRC Report
Bertrand Fougnie, Denis Jouglet, Patrice Henry
Sophie Lachérade, Eric Péquignot
CNES-DCT/SI/MO
+ support from CNES-DCT/ME

2. Williamsburg, Virginia
GSICS Annual Meeting 4-8th March 2013, Williamsburg, VA
Marquis de Lafayette
Williamsburg, Virginia

3. Summary 1/2 Cross-calibration over Desert
CEOS-IVOS Working Group 4 : webmeeting’12
Libya-4 workshop : webmeeting’12
Cross-calibration LEO/GEO  dedicated talk on SEVIRI
Synergic calibration  dedicated talk
the PARASOL work on
the Ocean Color Virtual Constellation
SEVIRI : webmeeting’12  dedicated talk
Calibration over Moon  dedicated talk
Intensive acquisitions with Pleiades – An introduction to “POLO” : Pleiades Orbital Lunar Observations

4. Summary 2/2 Calibration over Rayleigh Scattering  dedicated talk
Implementation for several sensors
Development plan
Starting the ATBD writing
Implementation for GEO – SEVIRI results
IASI cross-calibration  dedicated talks
Overview of IASI-B performances  opening day
Cross-calibration between IASI-A, AIRS, IASI-B, and CRIS
SADE Database opening

5. Cross-Calibration over Desert Sites

6. CEOS-IVOS Working Group 4
CEOS decision to setup small WG … to draft a CEOS endorsable best practice “procedure” for the various vicarious cal/val methodologies
WG4 on pseudo-invariant calibration sites (here Libya-4,Niger-2, Dome-C)
The WG4 (intentionally restricted)
Compare the results from 1/ selection and 2/ calibration
Understand differences between methodologies
Medium Resolution / Multi-spectral : VGT, MERIS, MODIS, PARASOL (4 years)
DIMITRI (ESA), MUSCLE/SADE (CNES), DMA (RAL), OSCAR (VITO)
Conclusion & lessons learnt
a clear definition of reference datasets, protocol and outputs is required
the extraction step (geographic + radiometric) is crucial for the performance
general consistency between methods within 2-3% (after spectral correction)
no significant bias between deserts BUT benefit to use different sites (snow/desert)
possibility to extend the set in the future
this exercise was beneficial for all methodologies (mistakes, limitations, improvements)
GSICS WebMeeting Nov’12

7. CEOS-IVOS Libya-4 Workshop
Focus technical exchange and experiences on one calibration site
on of the most widely used – not the best
geographical definition differs in general
Participants mainly European, but also US (space agencies, labs, industries)
Site characterization
Spectral behavior : to be improved using Hyperspectral / spectral lab + Model
BRDF: to be improved – CNES provide their current model for evaluation
Atmosphere : statistical approach
Improve surface of TOA characterization ?
Intercalibration results if spectrally close channels :
cross-calibration within 2-3%
multi-date better than 2% for long-term trend
absolute calibration : 5% (?)
difficulty in the blue
Paving the way for international collaboration and exchange
GSICS WebMeeting Nov’12

8. Desert sites – What’s new ?
ATBD – The IEEE TGARS Special Issue opportunity
Bidirectional characterization of sites
continuation of modeling using PARASOL data archive (bidirectional sensor)
automatic procedure have been operated to generate BRDF models
deep evaluation has to be done : made for Libya-4 (see WG)
currently not fully satisfying…
Prototyping of a new geometrical matching approach
use of BRDF to enlarge the matching on a larger geometrical window
Interest = largely increase the number of matchup when necessary
to be fully validated and pushed on the operational phase
Update of the MERIS archive – now Version 3
confirmation of the consistency with MODIS-Aqua within 1-2%
Construction and analysis of a SeaWiFS archive
behavior to be explained
Cross-calibration LEO/GEO through SEVIRI data
prototype phase – preliminary results under analysis
very preliminary results shown at webmeeting Dec’12
Cross-calibration with MODIS not yet available, but very soon….

9. Synergic Calibration

10. What does it mean ? Several calibration methods are operational
Statistical approach over natural targets
Desert, Rayleigh, Sunglint, Cloud-DCC, Antarctica, Moon
Each one has its own
behavior : magnitude, spectral, angular, polarized…
efficiency range
Different aspects of calibration
Indicative cartography – range of efficiency for each method

11. What does it mean ? See coming presentation 8d
Basic idea = develop the synergic use of several method in order to :
Take advantage of the complementarities of all method
Document the confidence from consistency between methods
Improve the “system calibration” when integrating various results
Assess radiometric aspects others that the absolute calibration
Recent example#1 : PARASOL end-of-life reCalibration
Multi-method Synergic Approach to derive corrections of
1/ variation of calibration inside the field-of-view
2/ temporal evolution of the mean calibration
3/ reevaluate the absolute calibration for the entire archive
Recent example#2 : Ocean Color Virtual Constellation
Multi-sensor Synergic Approach to better understand and document
1/ the calibration and radiometric behavior of each sensor
2/ the consistency between calibration
Recent example#2 : SEVIRI/MSG2
Multi-method Synergic Approach to
the calibration from a GEO orbit
See coming presentation 8d

12. Calibration over Moon

13. An introduction to “POLO”
It has been demonstrated that the Moon is a very precious way to provide accurate in-orbit monitoring of the radiometric drift
Activity under “big” development at CNES
Method implemented in the operational MUSCLE/SADE environment
Starting of Pleiades 1A and 1B commissioning phases in Jan’12 and Jan’13
Strong ability to “catch” the moon
Intensive acquisitions have been performed (recom phase = 40°)
1 moon every day during one lunar cycle
various moon cycles
several moons during the day : every orbit, 2 successively, half an orbit
1 moon simultaneously by PH1A and PH1B
This defines the Pleiades Orbital Lunar Observations – “POLO”
Intensive in-orbit acquisitions in various conditions
Goals are
to better understand the ROLO model on its operational form
to quantify the potential impact of programmation, conditions of acquisition (orientation), spatial sampling and resampling
to derive recommendations
to contribute to improve the use of lunar acquisitions
to develop the use for cross-calibration
See coming presentation 8h

14. Calibration over Rayleigh Scattering

15. Implementation
Historically developed with POLDER and Végétation sensors
definition, prototyping and improvements between
now stabilized on the reference Version 3.5
Implementation of Version 3.5 for several sensors
ocean color sensor considered as radiometric reference
SeaWiFS (prototype step)
MERIS (operational, reprocessed for data V3) also to prepare OLCI (Sentinel-3)
MODIS coming
high-resolution sensors (limited geographical coverage and matchups)
SPOT6
Pleiades 1A and 1B
geostationary sensor
SEVIRI
future sensors
Sentinel-2
Sentinel-3 (OLCI and SLSTR)
VENUS
SPOT7

16. Development Plan Why do we need to clarify a development plan
Better visibility on the state of the art for each sensor
Externally, but also internally
The method is labeled “operational”, but method =
step 1 = Data selection/extraction : specific step for each sensor (as if common baseline)
step 2 = Algorithm : computation of TOA signal – universal step, but need LUT
step 3 = matchup strategy : i.e. temporal/geometrical sampling : may be specific for each sensor
= not the same development status for each sensor
Development Plan for Calibration Method (MUSCLE/SADE)
First tentative for the reference method Rayleigh Calibration Version 3.5
(GSICS inspired graphical representation)
DEV = study & ATBD first definition [resp. SI/MO]
PROTO = prototype on dedicated test environment on MUSCLE [resp. SI/MO]
Final ATBD (data selection/extraction)
computation of LUT, parameterization of SADE/MUSCLE
Pre-OPE = test on the operational MUSCLE [resp. ME/EI]
OPE = fully operational method/procedure/processing
Traceability guaranteed [resp. ME/EI]

17. Development Plan
The reference method is Rayleigh Calibration Version 3.5
DEV = study & ATBD first definition [resp. SI/MO]
PROTO = prototype on dedicated test environment on MUSCLE – Final ATBD [resp. SI/MO]
Pre-OPE = test on the operational MUSCLE [resp. ME/EI]
OPE = fully operational method / Traceability guaranteed [resp. ME/EI]

18. Activities on Rayleigh Calibration
Error budget : Continuity of efforts  see presentation 8a about Rayleigh cal.
Construction of the error tree
Construction of the error factors
Results for SEVIRI  see presentation 4b about SEVIRI calibration
prototyped in MUSCLE/SADE
Rayleigh scattering results for synergic use  see presentation 8d
validation of the temporal monitoring
validation of the multi-angular calibration
ocean color virtual constellation
The GSICS-ATBD construction  see presentation 8a about Rayleigh cal.
first outlines for LEO sensors
See coming presentation 8a

19. IASI Cross-calibrations

20. IASI-B Performances IASI Commissioning Phase - Key dates
MetOp-B launch: 17th Sept 2012
IASI first interferograms (start of L1 CalVal): 23th Oct 2012
IASI first L0 spectra (computed on-board): 24th Oct 2012
IASI first L1 spectra (calibrated on ground): 25th Oct 2012
Last configuration update before IASI-B L1C trial dissemination:
On-board: 10th Jan 2013
Ground: 14th Jan 2013
IASI-B L1C trial dissemination (CalVal partners) in Near Real Time: 22th Jan 2013
IASI-B L1C trial dissemination (member states) in Near Real Time: 5th Feb 2013
See opening day’s presentation

21. IASI-B Performances See opening day’s presentation
After 3 months of IASI-B L1 CalVal
Instrument & interferogram acquisition are very stable and work perfectly
Space & ground segments are now working well with consolidated parameters. The in-depth tuning has started.
Performances are very encouraging and already of order of IASI-A

22. Massive Cross-calibration
The tool for inter-comparison is now operational for the 5 couples of sensors:
IASI-A / AIRS, IASI-A / CRIS
IASI-B / AIRS, IASI-B / CRIS
IASI-A / IASI-B
Major result: very accurate cross-calibration!
Bias between 0K and 0.2K, < radiometric absolute specification of 0.5K
IASI-B very close to IASI-A (bias ~0.1K)  continuity of the IASI mission
Work on-going:
Increase the size and relevance of the dataset
Go further in the interpretation of small differences
Perform IASI / AIRS and IASI / CRIS at high spectral resolution
Perform a spectral inter-calibration ?
The tool should be operational for a long time (decades for climatic studies)
 Inclusion of the future sensors (IASI-C, IASI-NG, etc.)
See presentation 5a

23. SADE Database Opening

24. SADE Database Opening
Few feedbacks from beta-users : only one (very positive…)
SADE access through CNES scientific mission website
(free access)
Password mandatory (for the “SADE data” page only)
A complete reprocessing of SADE exported files was produced in March 2012
Data extension up to 2011
New sensors :
Terra/Modis
Landsat 7
Theos
New MERIS reprocessing (3rd)
VGT1 updated calibration
Opening has been announced at the CEOS/IVOS Meeting (May 2012)
Nevertheless a small difficulty : no procedure yet available for password delivery (contact Aimé Meygret or Patrice Henry) including the data policy
If interested, please contact us