1EUM/RSP/VWG/16/ Tim Hewison Tom Stone Manik Bali Selecting and Migrating GSICS Inter-Calibration Reference Instruments

2EUM/RSP/VWG/16/ Introduction-GSICS References GSICS Reference Instruments are at the Center of instrument Monitoring and Classical GSICS Product Generation. Stability and accuracy (over time) of reference instrument are vital parameters for ensuring good quality of GSICS inter-calibration monitoring. AIRS IASI MODIS GSICS Aims [Ref: WMO website ]WMO website Monitoring instrument performances, Operational inter-calibration of satellite instruments- GSICS Products Operational inter-calibration of satellite instruments- GSICS Products Tying the measurements to absolute references and standards, and recalibration of archived data Slide from Manik Bali

3EUM/RSP/VWG/16/ Overview 1.Proposed Reference Instrument Selection Scheme 2.Prime GSICS Corrections (not for presentation, just for CGMS Report) Merging results from multiple references Anchor Reference Concept 3.GSICS Infrared Reference Sensor Traceability and Uncertainty Report 4.Requirements for lunar reference models (not for CGMS Report) 5.Conclusions

4EUM/RSP/VWG/16/ Proposed GSICS reference Instrument selection process 1.The instrument and Channels agency wishes to monitor 2.The method/s they would employ to monitor (e.g. single or blended references, use transfer target, stability criterion) 3.May consider scoring proposed by Hewison and Reference Expectations gathered by GSICS Survey 4.Demonstrated use of the instrument by member agencies and users for instrument monitoring 5.Comparison of Instrument design specification ( Pre-launch testing) with In-orbit behavior 6.May consider if in-orbit status of key parameters of Candidate Ref instrument are monitored and available to users ( such as ICVS) 7.Take Info ( global coverage, eq. cross time etc) related to instrument available (e.g. OSCAR) Process of Selection to be carried out within sub group. Slide from Manik Bali

5EUM/RSP/VWG/16/ Reference Instrument Selection Criteria 1. Basic requirements are essential properties for each product: Threshold (may be binary) Is it available for the date in question? (Essential for SNO, not for PICS) Does it cover at least part of the spectral range of monitored instrument? Does it generate sufficient collocations? Is its calibration sufficiently stable? Can it transfer the calibration to other Reference sensors? Is it routinely monitored against other Reference sensors? Is the full supporting documentation published? Does it belong to a committed series of sensors? 2. Additional desirable requirements – for all products in class: -reflect reduced uncertainties in inter-calibration, -up to a saturation point, represented by goal: Does it cover the full spectral range? At sufficiently high spectral resolution?

6EUM/RSP/VWG/16/ Proposed Anchor Reference Selection Scheme Review instrument performance parameters critical to role as inter-calibration reference For each parameter: Define Threshold requirement (min) - below which the instrument is not useful Define Goal (max) - above which no further uncertainty reduction Define Weighting - Based on coverage/contribution to uncertainty

7EUM/RSP/VWG/16/ Proposed Anchor Reference Selection Scoring Scoring Scheme for GSICS Near-Real-Time Correction for 2014 Geostationary Imager IR Channels ThresholdGoal Metop/IASIAqua/AIRSSNPP/CrIS (in FSR mode) NOAA/HIRS/2CLARREO UnitMinMaxMinMaxWeightOK?ScoreOK?ScoreOK?ScoreOK?ScoreOK?Score Date RangeYear OK7.5OK4.2OK5.8NOK0.4NOK0.0 Spatial Coverage: Latdeg OK1.0OK1.0OK1.0OK1.0OK1.0 Spatial Coverage: Londeg OK1.0OK1.0OK1.0OK1.0OK1.0 Dynamic RangeK OK1.7OK1.7OK1.7OK1.7OK1.7 Spectral Range SWIRµm OK1.6OK1.2NOK1.1OK1.4OK1.8 Spectral Range MWIRµm OK2.6OK1.4OK2.1NOK0.2OK2.6 Spectral Range LWIRµm OK5.2NOK2.6NOK2.6NOK2.6OK5.2 Geometric Range: VZAdeg 0602OK1.8OK1.8OK1.8OK1.8OK0.0 Diurnal Coveragehr 0125OK1.4OK1.4OK1.4OK1.4OK5.0 # Collocations/d OK4.0OK4.0OK4.0OK4.0OK4.0 Spatial resolutionkm OK0.0OK0.0OK0.0OK0.0OK0.0 Spatial samplingkm OK0.4OK0.7OK0.6OK0.4OK0.1 Geolocation accuracykm OK0.2OK0.2OK0.2OK0.2OK0.2 Radiometric StabilityK/yr OK0.2OK0.2OK0.2OK0.2OK10.0 Radiometric NoiseK OK0.7OK0.5OK0.5OK0.5OK0.2 Uncertainty from SBAFK OK10.0OK1.0OK1.0OK0.3OK10.0 Spectral Resolutioncm OK0.0OK0.0OK0.0NOK0.0OK0.0 Spectral Stabilitycm-1/yr OK0.0OK0.0OK0.0OK0.0OK0.0 Absolute Cal AccK OK2.0OK2.0OK2.0OK0.2OK3.0 Documented TraceabilityScore OK1.7OK1.7OK2.5OK0.8OK5.0 Total %54%94%37%91%41%85%29%94%62% Consider all monitored instruments in Class e.g. All GEO imagers in 2014 Date Range Reference must operate this year Ideally cover full life of all instruments Spectral Range Must cover centre of all GEO imager channels in each band Ideally cover full spectral band of all GEO imager channels in each band Weighting proportional to # GEO imager channels Other important parameters: Geolocation accuracy Radiometric stability Uncertainty from SBAF Absolute calibration accuracy Documented Traceability Chain (Scored 0-6)

8EUM/RSP/VWG/16/ Draft Scores for GSICS GEO-LEO IR NRTC Scoring Scheme for GSICS Near-Real-Time Correction for 2014 Geostationary Imager IR Channels ThresholdGoal Metop/IASIAqua/AIRSSNPP/CrIS (in FSR mode) NOAA/HIRS/2CLARREO UnitMinMaxMinMaxWeightOK?ScoreOK?ScoreOK?ScoreOK?ScoreOK?Score Date RangeYear OK7.5OK4.2OK5.8NOK0.4NOK0.0 Spatial Coverage: Latdeg OK1.0OK1.0OK1.0OK1.0OK1.0 Spatial Coverage: Londeg OK1.0OK1.0OK1.0OK1.0OK1.0 Dynamic RangeK OK1.7OK1.7OK1.7OK1.7OK1.7 Spectral Range SWIRµm OK1.6OK1.2NOK1.1OK1.4OK1.8 Spectral Range MWIRµm OK2.6OK1.4OK2.1NOK0.2OK2.6 Spectral Range LWIRµm OK5.2NOK2.6NOK2.6NOK2.6OK5.2 Geometric Range: VZAdeg 0602OK1.8OK1.8OK1.8OK1.8OK0.0 Diurnal Coveragehr 0125OK1.4OK1.4OK1.4OK1.4OK5.0 # Collocations/d OK4.0OK4.0OK4.0OK4.0OK4.0 Spatial resolutionkm OK0.0OK0.0OK0.0OK0.0OK0.0 Spatial samplingkm OK0.4OK0.7OK0.6OK0.4OK0.1 Geolocation accuracykm OK0.2OK0.2OK0.2OK0.2OK0.2 Radiometric StabilityK/yr OK0.2OK0.2OK0.2OK0.2OK10.0 Radiometric NoiseK OK0.7OK0.5OK0.5OK0.5OK0.2 Uncertainty from SBAFK OK10.0OK1.0OK1.0OK0.3OK10.0 Spectral Resolutioncm OK0.0OK0.0OK0.0NOK0.0OK0.0 Spectral Stabilitycm-1/yr OK0.0OK0.0OK0.0OK0.0OK0.0 Absolute Cal AccK OK2.0OK2.0OK2.0OK0.2OK3.0 Documented TraceabilityScore OK1.7OK1.7OK2.5OK0.8OK5.0 Total %54%94%37%91%41%85%29%94%62%

9EUM/RSP/VWG/16/ Overview 1.Proposed Reference Instrument Selection Scheme 2.Prime GSICS Corrections (not for presentation, just for CGMS Report) Merging results from multiple references Anchor Reference Concept 3.GSICS Infrared Reference Sensor Traceability and Uncertainty Report 4.Requirements for lunar reference models (not for CGMS Report) 5.Conclusions

10EUM/RSP/VWG/16/ Introducing Prime GSICS Corrections Define one Anchor GSICS Reference for each spectral band/application by consensus agreement within GSICS to provide reference standard datasets [QA4EO] Use others as Transfer References Blend corrections from all references after modifying Corrections to Anchor GSICS Reference Ensures long-term continuity without calibration jumps Ensures Traceability back to single Anchor Reference Simplifies users’ implementation

11EUM/RSP/VWG/16/ Correcting the Corrections & Blending References Reference-1 (Anchor) Monitored Instrument GSICS Correction, g 1 Mon  1 Reference-2 (Transfer) GSICS Correction, g 2 Mon  2 Mon  1 Delta Correction, g 1/2 2  1 Derived by GSICS Applied by User Corrected Correction, g 2,1/2 Mon  2  1 Prime GSICS Correction, g 0 Mon  1 - g̅ +

12EUM/RSP/VWG/16/ Users’ Application of Prime GSICS Correction Monitored Instrument Prime GSICS Correction, g 0 Mon  1 Mon  Ref1

13EUM/RSP/VWG/16/ Overview 1.Proposed Reference Instrument Selection Scheme 2.Prime GSICS Corrections (not for presentation, just for CGMS Report) Merging results from multiple references Anchor Reference Concept 3.GSICS Infrared Reference Sensor Traceability and Uncertainty Report 4.Requirements for lunar reference models (not for CGMS Report) 5.Conclusions

14EUM/RSP/VWG/16/ IR Reference Sensor Traceability & Uncertainty Report Introduction- Hewison Aims To support the choice of reference instruments for GSICS and IASI as Anchor To provide traceability between reference instruments (IASI, AIRS, CrIS) By consolidating pre-launch test results and various in-flight comparisons To seek consensus on the uncertainties in the absolute calibration of the reference sensors Limitations No new results, just expressing results of existing comparisons in a common way, reformatting where necessary, to allow easy comparisons. Error Budget & Traceability Focus on Radiometric and spectral calibration AIRS- Pagano + Wang? IASI - Jouget + Jacquette CrIS- Tobin + ? Inter-comparisons Introduction: Pros and Cons of each method - Wang Polar SNOs - Jouglet, Tobin, Wang Tandem SNOs (AIRS+CrIS) – Tobin Quasi-SNOs- Jouglet GEO-LEO Double Differencing- Hewison +? NWP Double-Differencing- Wu +? Regional Averages (“Massive Means”)- ? Aircraft Double-Differences- Tobin +? Reference other methods e.g. Dome-C Conclusions- All Target Time-scale: Web Meeting: - Agree structure, authors, templates Web Meeting: - Review Draft Error Budgets GRWG Meeting - Discuss presentation of results

15EUM/RSP/VWG/16/ IR Reference Sensor Inter-Comparisons Re-binning results of existing comparisons to make them comparable: Biases with respect to MetopA/IASI With standard uncertainties (k=1) At full spectral resolution - in CrIS channel-space – or in 10cm -1 bins within AIRS bands Averaged over specific spectral bands Or average results over broad-band channels With specific SRFs - rectangular? Converted into Brightness Temperatures For specific radiance scenes - e.g. 200K, 220K, 240K, 260K, 280K, 300K For all viewing angles and/or for specific ranges - e.g. nadir±10°? - not possible for QSNOs Need to check for scan-angle dependence - which methods can do this? Over specific period - e.g. at least 1 year Common 3 year period from IASI-B operational start to present ( / ) Noting any significant changes with time And Trends

16EUM/RSP/VWG/16/ Overview 1.Proposed Reference Instrument Selection Scheme 2.Prime GSICS Corrections (not for presentation, just for CGMS Report) Merging results from multiple references Anchor Reference Concept 3.GSICS Infrared Reference Sensor Traceability and Uncertainty Report 4.Requirements for lunar reference models (not for CGMS Report) - Tom 5.Conclusions

17EUM/RSP/VWG/16/ Overview 1.Proposed Reference Instrument Selection Scheme 2.Prime GSICS Corrections (not for presentation, just for CGMS Report) Merging results from multiple references Anchor Reference Concept 3.GSICS Infrared Reference Sensor Traceability and Uncertainty Report 4.Requirements for lunar reference models (not for CGMS Report) 5.Conclusions

18EUM/RSP/VWG/16/ Conclusions Prime Corrections merge results from multiple references Correcting all to be consistent with one Anchor Reference Based on series of double-differences wrt monitored instrument Need to progress to Demo mode! Selection of Anchor reference based on coverage/performance According to uncertainty contributions Inter-comparisons of different reference instruments GSICS IR Reference Sensor Traceability & Uncertainty Report Error Budgets, Traceability and Inter-Comparisons Requirements for lunar reference models Recommendation to CGMS to obtain the observations necessary to improve the lunar irradiance modeling capability to the point where it can be used as an absolute calibration reference for channels in the VIS/NIR with an uncertainty of<1% (k=1)

19EUM/RSP/VWG/16/ Thank You!