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MERIS Calibration Results

MERIS Calibration Results. Photo: Courtesy Alcatel Space Industries. Instrument Status. 6 months of successful in-orbit operation, 5 months under full MPS control , N o degradation or changes in telemetry data MERIS overall health is in excellent state. Absolute Geolocation:

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MERIS Calibration Results

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  1. MERIS Calibration Results Photo: Courtesy Alcatel Space Industries

  2. Instrument Status • 6 months ofsuccessful in-orbit operation, • 5 months underfull MPS control, • No degradation or changes in telemetry data • MERIS overall health is in excellent state

  3. Absolute Geolocation: • Requirement <2 Km • Measurement +/- 1 RR pixels • Instrument pointing offset is very • well characterized over (U.K. NL) • Pointing Stability is very good over the complete orbit Geo-located Image of Northern Australia Pointing Performance Summary

  4. Instrument Smile Spectrometric performances : Summary • Spectral Sampling interval: • Requirement 1.25 nm +/- 2 % • Measurement 1.25 nm +/- 0.2 % • Spectrometer dispersion is very linear and well within specification • Spectral band position: • Requirement < 1 nm • Measurement < 0.2 nm • Spectrometer in-flight characterization is well within specification

  5. Summary Radiometric Performance: Dark current characteristics • Mission Specifications: • 2% Orbital stability requirement • 0.5 % Orbital stability goal • Measured performance: • Orbital stability: 0.03 % before compensation • Smear band sensitive to SAA • No permanent damage to CCD • Instrument Offset is very stable and well within Specification • Actions needed: • Instrument to be operated in OCL ON

  6. SODAP Phase 6 Summary Radiometric Performance: NEDL / SNR • Mission Specifications: See chart • Measured performance: • All measured SNR are above the mission specifications • All Ocean Color bands are above the mission Goals (except 412nm) • SNR is well within Specification • Actions needed: None

  7. Summary Radiometric Performance: Instrument Stability / Degradation • Instrument Specifications: • 6% Absolute Radiometric accuracy goal • 1 % Absolute radiometric accuracy goal • Measured performance: • Diffusers Comparison • Identical +/- 0.5% • Characterization Accuracy < 0.5% • Model accuracy +/- 0.5% • Diffuser Degradation < 0.2 % • Instrument Degradation • Overall degradation < 2% • Blue bands are degrading slowly => Module 2 @ 412nm degrading fastest • Both Diffusers are nearly identical (BRDF) and very stable • Actions needed: Improve BRDF model based on in-flight data

  8. TOA Radiance from Field measurements • Railroad Valley Playa • TOA Normalised Radiance MERIS – AATSR • Orbit 2136 • TOA Radiances MERIS - SeaWiFS • Barrow (Alaska) 870 nm 3.5 % Complete orbit 4 % over Water 550 nm 5 % Complete orbit 6% over Water 670 nm 1 % Complete orbit 4 % over Water Radiometric Performance: Early Vicarious Calibration Results • All differences are within the limits of the vicarious calibration approachs

  9. Summary Radiometric Accuracy: • Absolute Radiometric accuracy: • Requirement < 6% => 1% Goal • Early Vicarious Calibration +/- 6 % • Diffuser BRDF Characterization accuracy < 1% • Diffuser BRDF model accuracy +/- 0.5% • BRDF model well within Specification => to be improve with in-flight data • Absolute Radiometric accuracy will be estimated using vicarious calibration results • Level 1b Processing Correction: • Non-Linearity will be switched ON, • Straylight correction will be switched ON • Smile correction will be performed in the Level 2 processing • MERIS Level 1b Radiance will be distributed with the instrument smile

  10. MERIS Level1b Algorithms: Summary • Level 1b processing performs as expected • Prototype and IPF are in line • Minor problems identified and solved during the period • No algorithm modification are required

  11. Routine Calibration Activities: Summary • Level 1b is ready to be transfered to operations • Routine Calibration • IECF will be transfered to operation by Mid-November • Continuity of data distribution via IECF-Metric tool • Systematic calibration activity • Cal / Val plan, • Support contract will begin in January 2003 • Quality Working Group will begin in January 2003 • The tools for insuring the product quality are available.

  12. Algal 1 Level 2 Verification: Summary • Initial Level 2 verification is very encouraging • Satisfying results for: • pixel classification • land products • cloud and water vapour products • ocean AC and turbid water identification • algal pigment index 1 • Additional tuning is needed for: • ocean atmospheric correction in all bands • case2 water constituents • surface pressure • water vapour above clouds

  13. Recommendations Level 1b corrections to be applied for Validation: • Non-Linearity • Straylight Smile correction will be applied at Level 2 Level 1b algorithms improvements • Include Smile information in the L1b products Spectral Calibration Campaigns • Repeat spectral campaigns with optimized band settings Diffuser Observations & Modelling • Improve BRDF model with in-flight data

  14. Recommendations (2) Processor Configuration • Post the processor & ADF configuration status Including a detail changes log. Routine Calibration • Include routine comparisons of AATSR – MERIS macro-pixels MERIS & AATSR Toolbox • Include a smile correction: L1b -> L1s

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