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Inter-Comparisons of AATSR, MERIS and ATSR-2 Calibrations using Desert Targets

Inter-Comparisons of AATSR, MERIS and ATSR-2 Calibrations using Desert Targets. Dave Smith - Rutherford Appleton Laboratory. Objectives.

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Inter-Comparisons of AATSR, MERIS and ATSR-2 Calibrations using Desert Targets

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  1. Inter-Comparisons of AATSR, MERIS and ATSR-2 Calibrations using Desert Targets Dave Smith - Rutherford Appleton Laboratory

  2. Objectives • Use remote desert sites to verify calibrations of AATSR and MERIS by comparison with other instruments (in particular ATSR-2), and in-situ radiometer measurements. • Long-term stability of sites will enable temporal calibration drifts to be determined. • Results can be extended to improve the calibrations of other instruments such as SCIAMACHY and AVHRR. • Crucial to blending of records of geophysical parameters derived from different sensors.

  3. Desert Calibration Targets Sudan - Egypt Sonora - Mexico

  4. Orbit 2136 comparison (MERIS/AATSR)

  5. AATSR AATSR AATSR MERIS MERIS MERIS 870 nm ATSR-MERIS Comparisons

  6. Orbit 2136 comparison (AATSR/ATSR-2) ATSR-2 870nm AATSR 870nm

  7. AATSR Data Processed to Date NOTE: Data before October 1st not used for validation

  8. Example ‘cloud’ test result Sonora, Mexico

  9. METRIC Extractions • METRIC tar files downloaded from MERIS Calibration Site (370 files to date) • No METRIC outputs for SONORA, Dunhuang, Hay, Amburla and Thangoo • HDF Files extracted from tar files and read by IDL routine • TOA reflectances extracted and stored in file for each site • Coincident MERIS and AATSR observations compared (11 match-ups so far) • How do METRIC cloud test results compare with AATSR?

  10. MERIS/AATSR Comparison 560nm RAATSR/RMERIS = 1.041 660nm RAATSR/RMERIS = 1.001 870nm RAATSR/RMERIS = 1.037

  11. ATSR-2 Desert Reflectances Use archive of ATSR-2 TOA Reflectances from 1995 to 2000

  12. AATSR/ATSR-2 Indirect comparisons RAATSR/RATSR-2 =0.945 RAATSR/RATSR-2 =1.081 RAATSR/RATSR-2 =1.132 RAATSR/RATSR-2=1.088

  13. AATSR vs. ATSR-2 Coincident Data

  14. Summary of Previous ATSR-2 Intercomparisons

  15. Summary of results obtained so far • First TOA reflectance extractions performed for selection of Desert targets for October 2002. • AATSR agrees well with MERIS RAATSR/RMERIS = 1.041 (560nm), 1.001 (660nm), 1.037 (870nm) • Significant differences observed between AATSR/MERIS and ATSR-2 RAATSR/RATSR-2 1.132 (560nm), 1.088 (660nm), 1.081 (870nm), 0.945 (1600nm) • Results consistent with other investigations (Haggolle, Govaerts)

  16. Remaining activities • Process remaining sites and coincident ATSR-2 data • MERIS/METRIC products for Sonora, Hay, Amburla, Thangoo and Dunhuang • Greenland Data – need data for period between May and August. • Atmospheric corrections • Walk through from raw data to calibrated radiances – identify possible processing errors • Long Term analysis – • Requires data products delivered on a regular (monthly) basis – preferably on CD-ROM rather than FTP site

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