1. Ongoing need for Re-Analysis Corrections? Tim Hewison
Special Issue of the IEEE TGRS on “Inter-Calibration of Satellite Instruments”:
Special Issue of the IEEE TGRS on “Inter-Calibration of Satellite Instruments”:
04 December 2018
Ongoing need for Re-Analysis Corrections? Tim Hewison

2. The GSICS Governor?

3. GSICS Corrections – NRTC/RAC Recap
GSICS Corrections are available in different flavours
For different applications
Near Real-Time, using data from asymmetric window e.g. [-14d,0d]
Re-Analysis using data from symmetric time window e.g. [-14d,14d]
Near Real-Time Correction
Re-Analysis Correction
Single Reference Sensor
NRTC
RAC

4. New Prime GSICS Corrections
Define one Primary GSICS Reference
For each spectral band/application
By consensus agreement within GSICS
Use others as Transfer References
Blend corrections from all references
After modifying Corrections to Primary GSICS Reference
Ensures long-term continuity
Without calibration jumps
Ensures Traceability
back to single Primary Reference
Simplifies users’ implementation
Could also blend multiple methods?

5. Correcting the Corrections and Blending References
Reference-1 (Primary)
Monitored Instrument
Reference-2
(Secondary)
GSICS Correction, g1 Mon1
GSICS Correction, g2 Mon2 -
Derived by GSICS
Delta
Correction, g1/2
21 +
Modified
Correction, g2,1/2
Mon 21 g̅
Prime GSICS Correction, g0 Mon1
MonRef1
Applied
by User

6. Users’ Application of Prime GSICS Correction
Monitored Instrument
Prime GSICS Correction, g0 Mon1
MonRef1

7. GSICS Corrections – NRTC/RAC Recap
GSICS Corrections are available in different flavours
For different applications
Near Real-Time, using data from asymmetric window e.g. [-14d,0d]
Re-Analysis using data from symmetric time window e.g. [-14d,14d]
Near Real-Time Correction
Re-Analysis Correction
Single Reference Sensor
NRTC
RAC
Multiple Reference Sensors
N/A
Prime RAC

8. GSICS Corrections – NRTC/RAC Uses
GSICS Corrections are available in different flavours
For different applications
Near Real-Time Correction
Re-Analysis Correction
Single Reference Sensor
Operational Processing Chains
Case Studies
Multiple Reference Sensors ?
Generating FCDRs?

9. GSICS Corrections – FCDRs
Previous Exec Panel decision:
“FCDRs are not GSICS Products”
But GSICS algorithms and coefficients can be used to generate FCDRs

10. Discussion on RAC/FCDRs
What is the difference between a Prime RAC and an Archive Re-Calibration/FCDR?
Consistent processing versions?
Timeliness?
Something else?
Do we need both?
Can GSICS support Archive Re-Calibration products?
Aren‘t they FCDRs?

11. GSICS Products for GEO VIS/NIR
Different GSICS products for different applications?
Proposal for Exec Panel:
GSICS Products for VIS/NIR channels
Based on blend of results from different methods
GSICS to recommend weightings for each channel
Based on relative uncertainties
To cover full dynamic range
Include results from all individual methods
Customisable weightings for different applications
„Start with something, but start“
get feedback and iterate!