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ODYSSEA In Arctic. Emmanuelle Autret, Jean-François Piollé IFREMER/CERSAT, 29280 Plouzané, France Emmanuelle.Autret@ifremer.fr jfpiolle@ifremer.fr. Outline. Method Input validation in Arctic L3S, L4 validation Conclusion. Method (1). GHRSST L2P products.
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ODYSSEA In Arctic Emmanuelle Autret, Jean-François Piollé IFREMER/CERSAT, 29280 Plouzané, France Emmanuelle.Autret@ifremer.fr jfpiolle@ifremer.fr
Outline • Method • Input validation in Arctic • L3S, L4 validation • Conclusion
Method (1) GHRSST L2P products Observation quality control, correction (sses), filtering « re-mapped » L3 products Selection based on proximity to analysis time and best quality « collated monosenso L3C products » (/day /sensor) Pre- processing steps Correction of large scale bias field for each sensor (daily reference: 0.25 gridded field) Intercalibrated collated products (/day /sensor) Merging of composite files « multisensor supercollated L3S products » (/day) Optimal interpolation Multi-sensor analysed field
Method (2) • Bias correction principles: • A daily 0.25° resolution L3 «reference field » is built every day as follows: • 1) Each source is remapped on the 0.25° grid (mean): • 2) A median of selected sensor data is kept at each grid point • 3) An OI is applied to get a complete reference field • 4) The error (correction) is determined as the difference between each sensor and the reference smoothed over 2°.
AATSR Validation (Arctic) North of 67 N Nighttime drifter measurements only
NOAA-19 Validation (Arctic) North of 67 N Nighttime drifter measurements only
L3S & analysis Validation (Arctic) North of 67 N Nighttime drifter measurements only
Analysis Validation North of 67 N Nighttime drifter measurements only
Conclusion • ODYSSEA uses a multisensor reference • ODYSSEA showed no bias in 2011 • Since then, ODYSSEA shows a seasonal bias: null in Autumn and significantly negative (-0.5K) in February. • bias correction is not efficient in the Arctic • all main sensors show a negative bias