Calibrations using desert targets

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 : 

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.

Desert Calibration Targets : 

Desert Calibration Targets Sonora - Mexico Sudan - Egypt

‘CNES’ Sites : 

‘CNES’ Sites

Other Sites : 

Other Sites

Analysis Method : 

Analysis Method

Orbit 2136 comparison (MERIS/AATSR) : 

Orbit 2136 comparison (MERIS/AATSR)

ATSR-MERIS Comparisons : 

ATSR-MERIS Comparisons

Orbit 2136 comparison (AATSR/ATSR-2) : 

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

AATSR Data Processed to Date : 

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

Example ‘cloud’ test result : 

Example ‘cloud’ test result Sonora, Mexico

METRIC Extractions : 

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?

MERIS/AATSR Comparison : 

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

ATSR-2 Desert Reflectances : 

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

AATSR/ATSR-2 Indirect comparisons : 

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

AATSR vs. ATSR-2 Coincident Data : 

AATSR vs. ATSR-2 Coincident Data

Summary of Previous ATSR-2 Intercomparisons : 

Summary of Previous ATSR-2 Intercomparisons

Summary of results obtained so far : 

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)

Remaining activities : 

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