Earth Observation Science

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Earth Observation Science
Reflections on the impact of wider access to
AATSR data through the Medspiration Project

David T Llewellyn-Jones
Space Research Centre University of Leicester
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AATSR SST and Medspiration

• The ATSR series pre-Medspiration
• Why is AATSR so good?
• GODAE-GHRSST and Medspiration
• Get it to the users on their own terms
• Scientific inter-comparisons and merged products
• Very very difficult before Medspiration GHRSST
• Data-merging, OSTIA and other operational systems
• From satellite to daily weather forecast
• Conclusions
• What has Mespiration Done for AATSR?

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Brief history of ATSR series

• ATSR-1, experimental AO Instrument on ERS-1,
  launched in 1991
• ATSR-2, experimental AO Instrument on ERS-2,
  visible channels added, launched in 1995
• AATSR on ENVISAT funded by user-agency (Defra,
  UK govt) to provide data as input to
  environmental policy development
• SLSTR (or do we mean ATSR-4?) on Sentinel 3
  operational ESA-provided sensor for GMES
  programme

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AATSR Scan sequence showing on-board
Calibration System
Blackbodies viewed every scan.
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(A)ATSR Principles of Operation

• 7 spectral channels
• 3 thermal IR at 3.7 µm, 11 µm, 12 µm
• 
  (similar to AVHRR)
• 4 Vis/NIR at 0.55 µm, 0.67 µm, 0.87 µm, 1.6
  µm)
• Field-of-view 1 km at nadir
• Swath-width 500 km
• Dual view of Earth Surface - at nadir and 55 to
  nadir
• Direct Observation of Atmospheric Effects
• Stable and Precise On-board Calibration
• 2 on-board black bodies for IR calibration
• in an exceptionally stable thermal environment
• Stirling Cycle Coolers
• cooling low noise detectors to 80K (near-optimum)

The ATSR secret weapons
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Plancks Radiation Law
Max Karl Ernst Ludwig Planck April 23, 1858
October 4 1947
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AATSR Scan Geometry
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AATSR Earth-viewing face
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How well does AATSR Perform?

• Comprehensive validation programme
• In situ observations made using radiometers and
  buoys
• Results show exceptional accuracy and stability
• Use of AATSR SST data show positive impact on
  climate analysis data-sets (Hadley Centre))

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A Validation Result M-AERI (Noyes, Minnett et
al) Results 01/2003-06/2005
dS nearest pixel dT /- 60 minutes dual
nadir M-AERI SD 0.1 K
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Global Anomaly Plots
AATSR monthly SSTs
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ATSR2/AATSR-NCEP
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SST Anomalies in East Equaturial Pacific
(1995-present)
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The Bering Sea Summer 2007
Bering Sea Box- Average Temperature measured by
ATSRs since 1991
Sept 2007 SST Anomaly
AATSR SST Sept 2007
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AATSR SST data-set Recent Developments

• Launch of Archive
• Seamless archive of re-processed SST from 1991 to
  present
• Future Continuity of AATSR-standard SST data
  secured through GMES/Sentinel Programme
• SLSTR on Sentinel 3
• ARC project in place for Future Development of
  SST Retrievals and Product quality
• Led by C Merchant (U of Edinburgh), wit U
  Leicester, RAL, UK Met Office and NOCS
• Take-up by new operational users
• as the DIRECT RESULT of GHRSST/Medspiration

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New Operational Users of (A)ATSR

• Medspiration/GHRSST has made AATSR 1Km data
  available to operational users in near real time
• Users include
• UK Met Office via OSTIA
• METEO France
• NOAA/NESDIS
• US Navy met services (NAVOCEAN)
• Australian Bureau of Meteorology
• others

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Impact of high-resolution SST boundary
specification on NWP - Meso Eta forecast, 30th
December 2000
(From Thiébaux et al, 2003)
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Sensor inter-comparisons before Medspiration
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Scientific Use of GHRSST data

• Multi-sensor SST data available in NRT
• All data-sets in same accessible format (netCDF)
• Excellent for inter-sensor comparisons, or to
  make up for poor coverage
• Or for rapid-response scientific analysis

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Example Gulf Stream
FOAM
AVHRR
AATSR
AMSR-E
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Inter-comparison Gulf Stream
AVHRR - AMSR-E
AATSR - AMSR-E
AATSR - AMSR-E
AVHRR - AMSR-E
TMI - AMSR-E
AVHRR - AATSR
AVHRR - AATSR
TMI - AMSR-E
Note different colour bar range
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Geostationary (SEVIRI) and AATSR Data
(Pierre LeBorgme, Meteo France, Lannion)
Simple combination of SEVIRI data with AATSR
data. Differences are 1.5-2.0
With bias correction, based on difference between
AATSR-SEVIRI SSTs, applied to SEVIRI data
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AATSR
AVHRR
AVHRR
AMSR-E
AATSR
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Summary and Conclusions

• Pre-Medspiration, AATSR had very poor profile
• Despite a very stable measuring system
• and excellent validation results
• Medspiration introduced
• a global NRT service
• plus some quality information
• plus the opportunity to compare with data from
  other sensors
• and then to combine with data from other sensors
• Result?

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What has Medspiration done for AATSR?

• AATSR data now recognised by established
  large-scale users as the benchmaekm for SST
  measurements
• Medspiration facilitiates Data-merging techniques
  e.g. (SEVIRI-AATSR) which enable users to
  overcome the coverage limitatrions of AATSR
• Scientific inter-comparisons greatly facilitated
• AATSR data now are used in operational NWP
  schemes
• and, to conclude

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Conclusion

• ATSR data, through Medspiration, have taken a
  place in internationally recognised operational
  systems
• Moreover, recognised by users as the yardstick
  for accuracy,
• AATSR data are now essential to those and the
  question of replacement in case of
  non-availability has become serious
• This position could not have been reached
  without Medspiration!!

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Some Acknowledgements

• UK Department of Environment, Food Rural
  Affairs (Defra) who are the main funding body and
  owners of AATSR
• European Space Agency (ESA)
• who are flying AATSR on their Envisat satellite
• and who are funding Medspiration
• AATSR instrument team at RAL and in UK
  Australian industry, who built AATSR
• AATSR Validation Team who have established the
  accuracy of AATSR
• And, of course, GHRSST, for pushing the user
  requirements and the international dimension

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ENVISAT Europes largest satellite
Simply
AATSR
the BEST!!
, launched March 2002 Sun-synchronous orbit, 1030
local time daylight descending