SUBGROUP

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CEOS LAND PRODUCT

• SUBGROUP
• Definitions and workshop objectives
• Jeffrey T. Morisette, Ph.D.
• jeff.morisette_at_nasa.gov, [phone]
• Missoula Montana7 August 2006

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CEOS WGCV Definition

• Validation
• the process of assessing by independent means the
  quality of the data products derived from the
  system outputs
• (LPV will operates under this definition, but
  also with the understanding that validation
  activities should consider user accuracy needs
  and feedback to algorithm improvements.)

Justice, C., Belward, A., Morisette, J., Lewis,
P., Privette, J., Baret, F., 2000, Developments
in the validation of satellite products for the
study of the land surface, International Journal
of Remote Sensing, v. 21 (17) 3383 3390
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CEOS validation hierarchy

• Stage 1 Validation  Product accuracy has been
  estimated using a small number of independent
  measurements obtained from selected locations and
  time periods and ground-truth/field program
  effort.
• Stage 2 Validation Product accuracy has been
  assessed over a widely distributed set of
  locations and time periods via several
  ground-truth and validation efforts.
• Stage 3 Validation Product accuracy has been
  assessed and the uncertainties in the product
  well established via independent measurements
  through a systematic and statistically robust
  sample representing global conditions.

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LPV Objectives

• providing a forum for discussion of current
  issues and for exchange of technical information
  on efficient approaches to global land product
  validation
• increasing the quality and economy of land
  product validation by developing standards and
  protocols for field sampling, error budgeting,
  data exchange, and product evaluation
• facilitating international cooperation and
  coordination of validation activities by sharing
  information on instruments, analyses, and field
  activities

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LPV Publications

• Special Issue on Global Land Product Validation
  (Morisette, Baret, and Liang guest editorsIEEE
  TGARS July 2006, vol. 44, no. 7

• Best Practicies for Global Land Cover
  Validation
• Strahler Boschetti, Foody, Friedl, Hansen,
  Herold, Mayaux, Morisette, Stehman, Strahler,
  Woodcock

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httplpvs.gsfc.nasa.gov
Matches WGCV page layout and graphic

• Pull-down menu for main topical areas
• Land cover
• Biophysical
• Fire/Burn
• Surface Radiation
• Each pull-down lists
• Background
• Producers
• Meetings
• Case studies
• Intercomparisons
• input needed

• Quick links to
• Listserves
• Announments
• WGCV
• CEOS and
• CEOS calendar

web curator Jaime Nickeson, NASA GSFC
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Why validate global land products

• Committee on Earth Observing Satellites (CEOS)
  definition validation Estimating
  Uncertainty
• Good science and resource management require
  understanding of product accuracy/uncertainty
• Explicit statements of uncertainty fosters an
  informed user community and improved use of data
• Use of products for policy analysis implies
  products may be independently evaluated and
  possibly challenged
• As more, and similar, global products are
  produced by NASA other CEOS members, inter-use
  will require characterization of each products
  uncertainty

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Current Validation Framework
Field data
High resolution imagery
Aggregate Relate
High resolution Product
Moderate resolution Product
Accuracy Assessmentfor one product, at one site,
at one point in time
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Time-series data
Year close up 2000 - 2004
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Phenology parameters TIMESAT

• Beginning of season
• End of season
• Length of season
• Base value
• Peak value
• Time of peak
• Amplitude
• Left derivative
• Right derivative
• Integral over season (absolute)
• Integral over season (scaled)

TIMESAT - a program for analyzing time-series of
satellite sensor dataPer Jonsson Lars Eklund,
Computers Geosciences 30833-845, 2004.
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Considering the time component
Current validation activities address the
accuracy of a specific parameter at one or more
points in time.
GPP
time
Validation of phenological parameters requires
quantifying the uncertainty in the time domain.
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Meeting Objectives

• Assess the current state of global vegetation
  index time series data accuracy
• and
• methods used to quantify the uncertainties in
  seasonal/phenology metrics and long-term land
  surface process studies

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Meeting Approach

• Existing validation studies
• New Opportunities for time-series validation
• Requirements from the users perspectives
• Discussion on steps forward