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ERS - ENVISAT SYMPOSIUM Gothenburg 16-20 October, 2000 MERIS Instrument Calibration.

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Presentation on theme: "ERS - ENVISAT SYMPOSIUM Gothenburg 16-20 October, 2000 MERIS Instrument Calibration."— Presentation transcript:

1 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 MERIS Instrument Calibration

2 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 OPTICAL DESIGN

3 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 ON-BOARD PROCESSING

4 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 GEOMETRIC CALIBRATION

5 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 FROWN < 1/3 FR PIXEL DISTORTION & SKEW < 1/5 FR PIXEL CAMERA DEPOINTING +/- 1/3 FR PIXEL (after corrections) RESAMPLING METHOD = NEAREST-NEIGHBOUR ACROSS TRACK GRID = PSEUDO-EQUAL DISTANCE PROJECTED ON WGS84 ELLIPSOID OVERLAPING PIXELS REMOVED GEOMETRIC PERFORMANCE

6 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 GEOGRAPHIC VALIDATION METHOD REDUCED RESOLUTION GLOBAL COVERAGE USING CIA VECTOR SHORELINE FULL RESOLUTION GROUND TRUTH i.e. OIL RIGS PLATFORM ATTITUDE CONTROL LAW OFFSETS OBJECTIVES 2000 m IN REDUCED RESOLUTION

7 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 SPECTROMETRIC CALIBRATION

8 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 BANDPASS CHARACTERISATION 9 DETECTOR 9 VIEWS INSTRUMENT MODEL 15 BANDS ALL PIXELS

9 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 SMILE PERFORMANCE

10 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 SPECTRAL CALIBRATION ERBIUM DOPED “PINK” DIFFUSER TWO FEATURES WILL BE 520 nm & 650 nm ACCURACY < 1nm SYSTEMATIC MONITORING EVERY THREE MONTHS

11 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 VICARIOUS CALIBRATION OBJECTIVE ACCURACY OF nm METHOD OBSERVATION WITH BANDS SETTINGS: FRAUNHOFER LINES: Ca (393 & 396nm), Na (589nm), Ca II (853 nm) OXYGEN ABSORPTION LINES: 15 BANDS ( nm) LEVEL 2 PRESSURE PRODUCTS: SPECTRAL SHIFT INDEX

12 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 RADIOMETRIC CALIBRATION

13 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 RADIOMETRIC MODEL BASED ON DIFFUSER BRDF SOLAR IRRADIANCE = THUILLIER BANDPASS

14 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 DIFFUSER BDRF ON-GROUND CHARACTERISATION (<1%) ROUND-ROBIN WITH NASA (<1%) IN-FLIGHT CHARACTERISATION: ALONG TRACK BETWEEN DIFFUSERS FEEDBACK <= VICARIOUS CALIBRATION BRDF MODEL

15 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 STRAYLIGHT ASAP INSTRUMENT MODEL INCLUDED IN CALIBRATION MODEL VALIDATION

16 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 NON-LINEARITY CHARACTERISED AT UNIT LEVEL CORRECTIONS APPLIED AT CCD OUTPUT MODEL VALIDATION

17 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 VICARIOUS CALIBRATION SITES SYTEMATIC ACQUISITION & PROCESSING OVER ALL TARGETS

18 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 ABSOLUTE CALIBRATION RAYLEIGH INTER-BAND CALIBRATION SUN GLINT INTER-COMPARAISON WITH OTHER SENSORS - DESERT SITES CALIBRATION APPROACH CALIBRATION USING ON-BOARD DIFFUSERS

19 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 CALIBRATION ACCURACY VICARIOUS CALIBRATION RAYLEIGH < 4% ABSOLUTE SUN GLINT +/- 1% RELATIVE INTER-BANDS DESERT SITES < 4% ON-BOARD DIFFUSERS BRDF < 2 % SPECTRAL DEPENDENCE < 2%

20 ERS - ENVISAT SYMPOSIUM Gothenburg October, 2000 MERIS STABLE U.V. PROTECTED POLARISATION INSENSITIVE COOLED DETECTOR 2 PROTECTED DIFFUSERS SYSTEM CALIBRATION EVERY 15 DAYS VICARIOUS DATA ACQUISITION IS CONTINUOUS GOALS 4 % FOR THE RELEASE OF LEVEL 1B PRODUCTS 2% < BY THE END OF THE MISSION


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