Transcript Leicester - ESA Earth Online

Comparison of AATSR SST with
other sensors
David Ridley
Marianne Edwards
Space Research Centre
University of Leicester
Validation Workshop, 9-13th December 2002, ESRIN
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Comparison with global datasets
 Comparison of global monthly mean AATSR SST data with:•
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ATSR-2
AVHRR
MODIS
ECMWF
TMI
 To date, comparisons performed between AATSR data and MODIS,
ECMWF and TMI for September 2002
 Data compared are monthly means, at half degree resolution
 AATSR data used: spatially averaged product, dual view SST
retrieval, all available data
Validation Workshop, 9-13th December 2002, ESRIN
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Methodology
 Difference images produced to find areas of discrepancy for more
detailed analysis.
 Time series analysis.
Validation Workshop, 9-13th December 2002, ESRIN
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AATSR vs ECMWF
Sept 2002
ECMWF: 2.5 degree
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Mean global difference: -0.05 deg K
Mean absolute difference: 0.88 deg K
Standard deviation: 1.43 deg K
Tropical region (+/- 30 degrees)
• Mean difference: -0.40 deg K
• Standard deviation: 0.88 deg K
• Percentage of values between +/- 0.6 deg K: 54.82
Validation Workshop, 9-13th December 2002, ESRIN
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AATSR vs TMI
Sept 2002
TMI data: 0.25 degree
Binned to half degree
for comparison
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Mean global difference: -0.38 deg K (TMI warmer)
Mean absolute difference: 0.50 deg K
Standard deviation: 0.55 deg K
Tropical region (+/- 30 degrees)
• Mean difference: -0.42 deg K
• Standard deviation: 0.50 deg K
• Percentage of values between +/- 0.6 deg K: 68.48
Validation Workshop, 9-13th December 2002, ESRIN
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AATSR vs MODIS
Sept 2002
MODIS: 36km,
SST from 11 micron day/night
 Mean global difference: -0.41deg K (MODIS warmer)
 Standard deviation: 0.75 deg K
 Tropical region (+/- 30 degrees)
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Mean difference: -0.41 deg K
Standard deviation: 0.51 deg K
Percentage of values between +/- 0.6 deg K: 65.63
Validation Workshop, 9-13th December 2002, ESRIN
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Conclusions
 Preliminary results - comparisons performed for AATSR data
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and SST from ECMWF analyses, MODIS and TMI data, for
September 2002
Difficult to see patterns with one month’s data. More data and
processing needed, including comparisons with AVHRR and
ATSR-2.
Further investigations needed.
• How accurate are TMI and MODIS against buoy data?
• Spot checks using precision radiometers
Validation Workshop, 9-13th December 2002, ESRIN
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