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

The GSICS Governor?

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

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?

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

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

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

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?

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

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?

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!