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Past

Past. Evaluation of AC already exists in journals: SeaWiFS: Zibordi et al. (2006, 2009); Banzon et al., 2009; Jamet et al. (2011); MODIS-AQUA: Zibordi et al. (2006, 2009); Wang et al. (2009), ;Werdell et al., 2010;

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Past

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  1. Past • Evaluation of AC already exists in journals: • SeaWiFS: Zibordi et al. (2006, 2009); Banzon et al., 2009; Jamet et al. (2011); • MODIS-AQUA: Zibordi et al. (2006, 2009); Wang et al. (2009), ;Werdell et al., 2010; • MERIS: Zibordi et al. (2006, 2009); Cui et al. (2010); Kratzer et al. (2010); Melin et al. (2011) • BUT most of the time only about a specific AC (with eventually comparisons with the official AC)

  2. Now and Future • CCI: round robin of MERIS AC (only in open ocean for the moment) • What can we do with all those algorithms? • Some implemented in SeaDAS or BEAM (or ODESA) • What is the message for end-users studying coastal waters? • Are their accuracies enough/satisfying? • Use of a round-robin on AC over coastal waters? • Do we need improvements? • Round-robin for bio-optical algorithms (new IOCCG WG chaired by K. Ruddick)  How to take into accounts the uncertainties on Rrs?

  3. approaches to account for Rrs(NIR) > 0 sr-1 overlap • many approaches exist, here are a few examples: • assign aerosols () and/or water contributions (Rrs(NIR)) • e.g., Hu et al. 2000, Ruddick et al. 2000 • use shortwave infrared bands • e.g., Wang & Shi 2007 • correct/model the non-negligible Rrs(NIR) • Siegel et al. 2000 used in SeaWiFS Reprocessing 3 (2000) • Stumpf et al. 2003 used in SeaWiFS Reprocessing 4 (2002) • Lavender et al. 2005 MERIS • Bailey et al. 2010used in SeaWiFS Reprocessing 2010 • Shanmugam, 2012 any sensor • Wang et al. 2012 GOCI • use a coupled ocean-atmosphere optimization • e.g., Chomko & Gordon 2001, Stamnes et al. 2003, Jamet et al., 2005, Brajard et al., 2006a, b, 2008; Ahn and Shanmugam, 2007; Kuchinke et al. 2009; Steinmetz e al., 2010 Slide from presentation of Jeremy Werdell

  4. Evaluation of AC • Can round robin lead to improvements? • What can we learn? • Drawbacks and advantages • Limitations • Sensitivity studies • Fixed aerosols Variation/change of the bio-optical model • Fixed bio-optical model  Variation/change of the aerosol models • Uncertainties propagation and budget on the hypothesis • Ruddick et al. (2000) • Bayseian statistics for NN (Aires et al., 2004a, 2004b, 2004c) • Uncertainties on the NN parameters (weights) • Uncertainties on the outputs • Others ?

  5. Fig.8. Effect of a 10% positive error on the estimation of ε as defined by R00. correspond to the match-ups for the MVCO site and for AAOT site. Jamet et al., RSE, 2011

  6. Fig.9. Effect of a 20% positive error on the spectral dependence of the bb(λ), rbb(λ) as defined by S03. correspond to the match-ups for the MVCO site and for AAOT site (Jamet et al., RSE, 2011)

  7. Evaluation of AC • Can round robin lead to improvements? • What can we learn? • Drawbacks and advantages • Limitations • Sensitivity studies • Fixed aerosols Variation/change of the bio-optical model • Fixed bio-optical model  Variation/change of the aerosol models • Uncertainties propagation and budget on the hypothesis • Ruddick et al. (2000) • Bayseian statistics for NN (Aires et al., 2004a, 2004b, 2004c) • Uncertainties on the NN parameters (weights) • Uncertainties on the outputs (errors bars and correlation structure of errors) • Others ?

  8. Evaluation of AC • Which datasets • Which sensors? • Which parameters: only nLw or AOP (could be used as quality control for reconstruction of Lt)? • Vicarious calibration? seems like it is not necessary?

  9. Datasets • Simulated • Report #10: Maritime and urban models with RH=80% (Shettle and Fenn) • Which radiative transfer code? • Which bio-optical model? • Which aerosol models (NASA, Santer, ….) • Necessary? • Use for sensitivity tests?

  10. Datasets • In-situ • AERONET-OC • NOMAD • MERMAID • LOG (Eastern English Channel, French Guyana, Vietnam) • Others ?? • Which match-ups protocols (Bailey, 2006) ? • Only match-ups or also images analysis or also time series over sites?

  11. Datasets • In-situ • AERONET-OC • NOMAD • MERMAID • LOG (Eastern English Channel, French Guyana, Vietnam) • Others ?? • Which match-ups protocols (Bailey, 2006) ? • Only match-ups or also images analysis or also time • Weakly and moderately waters

  12. Datasets • In-situ • AERONET-OC • NOMAD • MERMAID • LOG (Eastern English Channel, French Guyana, Vietnam) • Others ?? • Which match-ups protocols (Bailey, 2006) ? • Only match-ups or also images analysis or also time series over sites?

  13. Datasets • In-situ • AERONET-OC • NOMAD • MERMAID • LOG (Eastern English Channel, French Guyana, Vietnam) • Others ?? • Which match-ups protocols (Bailey, 2006) ? • Only match-ups or also images analysis or also time series over sites?

  14. Datasets • In-situ • AERONET-OC • NOMAD • MERMAID • LOG (Eastern English Channel, French Guyana, Vietnam) • MUMM • Others ?? • Which match-ups protocols (Bailey, 2006) ? • Only match-ups or also images analysis or also time series over sites?

  15. Improvements of AC • Which perspectives? • Which wavelengths? • S3: 300-1020 nm • GOCI-I: 400-865 nm • MODIS-AQUA:405-2130 nm • HSI: 420-2450 nm (hyperspectral) • VIIRS:402-11,800 nm • GOCI-II: 412-1240 nm • GEO-CAPE: 350-2135 nm • ACE: 350-2135 nm • SGLI: 380-12,000 nm • Is it possible to have a global AC?

  16. Creation of a IOCCG WG • IOCCG considers proposals for new working groups at its annual Committee Meetings (usually held in January/February). Generally only one to two new working groups can be funded each year. The outline for a new IOCCG working group proposal should include the following sections, and should be 2 to 4 pages in length: • Proposed by (name, affiliation, and contact information) • Working group title • Scientific and programmatic background and rationale • Terms of reference • Proposed membership • Draft time line • Submission at least 3 months before the IOCCG meeting (5-7 February, 2013)

  17. Results • Only turbid waters (Robinson et al., 2003): nLw(670)>0.186 • Comparison of the normalized water-leaving radiances nLwbetween 412 and 670 nm and of the aerosol optical properties (the Ångström coefficient (510,865) and the optical thickness (865)) # of matchups for each algorithm and each AERONET-OC site

  18. (a) (b) Variation of the RMS (a) and the relative error (b) as a function of the wavelength obtained with S03R2007 ( ), R00R2007 (), S03R2009 (*), R00R2009 () and K09 ().

  19. Scatter plots of the retrieved τ(865) (left panel) and α(510) (right panel) by S03R2007 ( ), R00R2007 (), S03R2009 (*), R00R2009 () and K09 () vs AERONET-OC measurements at the MVCO and AAOT sites. The continuous line represents the 1:1 line, the line -- represents the linear regression for S03 and the line -.- represents the linear regression for R00.

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