PHAVEOS - the PHenology And Vegetation EO Service.

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PHAVEOS - the PHenology And Vegetation EO
Service.
Lankester, T., Dash, J.1, Baret, F.2, Koetz, B.3
Hubbard, S.
Presented by Thomas Lankester 18th June 2010
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Objectives

• Provide time series of a range of vegetation
  parameters, utilising the unique spectral,
  spatial and temporal resolution of the MERIS
  instrument
• Make spatially and temporally continuous time
  series available through visualisation and
  download of maps and phenology curves for
  individual locations
• Support the development of a validated baseline
  time series (2005 - ) in advance of the launch of
  Sentinels 2 and 3

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Level 1b to Level 3 processing approach

• Convert MERIS Level 1b data to Level 3 gridded
  maps, on a daily basis
• geometric correction
• radiometric correction
• atmospheric correction
• derive biophysical variable(s)
• resample direct to target map grid (latlong,
  OSGB36, Irish Grid)

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Level 1b geometric accuracy issues
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Level 1b geometric accuracy issues
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Level 3 geometric accuracy

• To preserve geometric fidelity, resampling into
  the target map grid is carried out in a single
  step

• To conserve the scene statistics area weighted
  (flux-conserving) resampling is used

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Level 4 processing - interpolation
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Level 4 processing - smoothing
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Level 4 processing interpolation metrics
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Level 4 processing smoothing metric
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Level 3 validation

• Moving from Stage 1 to Stage 2() validation
  requires considerable product generation
• PHAVEOS is utilising the ESA Grid Processing
  On-Demand (G-POD) environment
• Based on MERIS FRS data from 2005 present, will
  deliver a range of Level 3 and Level 4 time
  series
• LAI, fAPAR, fCover, MTCI, NDVI, 2G_RBi, .
• Provision of Level 3 products for MODIS match up
  sites (N. America)
• Coverage of PAR_at_METER sites
• OnLine Interactive Validation Exercise (OLIVE)

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Level 4 validation

• Land Surface Phenology product validation methods
  TBD.
• issues of spatial disparity where Sentinel 2
  could bridge the gap.
• Access to Forestry Commission intense monitoring
  sites (leaf litter collections, phenocams)
• Access to UK Phenology Network
• Access to tropical (DRC) deforestation ground
  truth

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Web Map Service dissemination concept
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Phenology metrics what is the point?

• Why use, and validate / inter-compare, basic
  phenology statistics?
• Loss of information from a continuous time series
  (are we hiding intra-annular information)
• Why inter-compare on a handful of measures when
  full time series are available?
• Extraction of metrics is sensitive to interaction
  of smoothing and metric extraction methods
• Different users are interested in different
  aspects of time series (phenology curves)
• Are simple metrics capturing a relevant reality?

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Phenological beauty is in the eye of the beholder
Any questions