LEGOS Downstream Quality Checks

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LEGOS Downstream Quality Checks
LEGOS user expertise on sea level
observation LEGOS routine data
processing LEGOS hydrodynamic modelling
- Harmonic analysis of the time series - Detided
signal comparison (observed versus modelled)
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Tidal constants misfits
- comparison with tidal constants from existing
archives, - comparison with tidal constants from
tidal hydrodynamic models, - comparison with
tidal constants from altimetry
LEGOS collected data bank, courtesy of the
MEDGLOSS/SONEL data providing hydrographic offices
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Tidal models constants misfits
Easy reading of the misfits
- Map from LEGOS graphic interface Xscan -
Statistics files
Identified problems
Mainly clock shift GMT/local time
MOG2D model, global version
LEGOS collected data bank, courtesy of the
different data providing offices
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High frequency signal comparison
Smoothed variability of the difference between
detided observations and storm/ surge model
simulations for T lt 20days
using MOG2D Med Sea high resolution model
(LEGOS)
Erroneous data
Data from the LEGOS collected data bank,
courtesy of SHOM and CNES
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LEGOS high quality products

• - Harmonic constants with error bars of 75 tidal
  components,
• - Detided time series (4 products)
• obs-LF-HF, obs-HF, obs-LFmod-HF, Demerliac
  (obs-LFmod-HF)
• - Global regional models (NEA, Medsea very high
  resolution),
• 10 years of simulation of HF ocean response to
  meteo forcing available, simulations continuously
  updated (presently november 1992 upto october
  2002)
• - Altimetric data expertise,
• - Data processing algorithm development

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Albicocca project
LEGOS/CNES/CERGA/ENEA

• Objectives
• Jason altimeter regional calibration
• Altimetry observation exploitation for coastal
  ocean dynamic in conjunction with in situ data
  (tide gauges, moored buoys, opportunity XBTs, )

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Correlation on the detided ssh at the satellite
cross-over point and the tidal gauge (Nice
Xover 009-222)
SSH correlation

• Green linessh without correction
• Blue linessh signal corrected by the inverse
  barometer
• Red linessh signal corrected with the mog2d
  model.

SSH correlation
Time lag (in day)
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Numerical simulations regional domains
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Conclusions - perspectives
Contributions to ESEAS via SONEL

• CNES tide gauges records for the ESEAS
• LEGOS products on ESEAS web site
• LEGOS collaborations
• - data quality control,
• - sea level models and softwares,
• - altimetric products (from CTO) and expertise