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Evaluation of the IDPS (VOCCO) ocean color products Impact of “non-zero” nLw 765 i.e. - Coastal NIR and atmospheric correction. VIIRS Ocean Color cal val team June 6 , 2013. R. Arnone, S. Ladner Stennis - USM, NRL, QNA. Objective:.
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Evaluation of the IDPS (VOCCO) ocean color productsImpact of “non-zero” nLw 765 i.e. - Coastal NIR and atmospheric correction VIIRS Ocean Color cal val team June 6 , 2013 R. Arnone, S. Ladner Stennis - USM, NRL, QNA
Objective: • Define Limitations of the presentIDPS VIIRS processing for ocean color in high scattering waters • ( VOCCO failures) • Evaluate the impact of negative radiance in high Scattering waters for VOCCO • Demonstrate how VIIRS IDPS products can be improved • Need for a DR to be established for the NIR processing
Ocean Color Processing: Lt = total Lr = Rayleigh La = Aerosol Lu = water Color Lt (l) = Lr(l) + La(l) + Lu(l) Aerosol Ocean Rayleigh Total Black Water Assumption 0 La (865) = Lt(865) – Lr(865) - Lu(865) Atmospheric correction Assumption In high water scattering the Lu 865 = 0 Can be handled using an “ iteration or Coastal NIR processing procedure. Uses the spectral water backscattering to derive the Lu(865). (NASA, NOAA and Navy processing)
Evaluation of the IDPS VOCCO ocean products Failures April 26, 2013 IDPS = 320 mg/m3 APS w/NIR = 2.2 mg/m3 APS no NIR = 2.5 mg/m3 Focus on the Chesapeake Bay Retrievals Failures Neg Rrs VOCCO • Chlorophyll _a APS Processing - Coastal NIR Iteration APS Processing No Coastal NIR Iteration Turned off COASTAL NIR EDR VOCCO Processing No Coastal NIR Iteration
Evaluation of the IDPS ocean products and Coastal NIR nLw 410nm Colored Pixels = negative Gray Scale = positive Positive Negative NRL Processing Coastal NIR Iteration NRL Processing No Coastal NIR Iteration EDR Processing No coastal Iteration
Evaluation of the IDPS ocean products and Coastal NIR nLw 443 nm Colored Pixels = negative Gray Scale = positive Positive NRL Processing No Coastal NIR Iteration EDR Processing No Coastal Iteration NRL Processing NIR Iteration
Evaluation of the IDPS ocean products and Coastal NIR nLw 486nm Colored Pixels = negative Gray Scale = positive Positive NRL Processing No NIR Iteration EDR Processing No Coastal NIR Iteration NRL Processing NIR Iteration
Evaluation of the IDPS ocean products and Coastal NIR nLw 551nm – All Positive Colored Pixels = negative Gray Scale = positive Positive NRL Processing NIR Iteration NRL Processing No NIR Iteration EDR Processing No Coastal NIR Iteration
April 26, 2013 – Chesapeake bay Transect . Affect of the Coastal NIR processing Line 1
Evaluation of Coastal NIR Chesapeake Bay Transect 1 Line 1 APS + NIR APS - No NIR VOCCO - No NIR Line 2 Impacts the AEROSOLS
STAR Coastal Data sets Upper Chesapeake Bay ( Mike Ondrusek ) Validation of the Coastal IR using NASA and APS processing 4 Cruises show similar results 4/25, 4/26 , 5/1, 5/2 2013 Results April 25,26 6 , May 1,2 – Matchup VOCCO 410, 440, 488 Negative nLw(555) ~ 56% low nLw(672) ~ 89% low Chesapeake Bay Sample Locations May 1, 2 2013 April 1, 2, 2013
US East Coast 04/06/13 APS - VIIRS IDPS VIIRS Note Higher Chl for High Conc. Lower Chl for Low Conc.
Summary: Black Water assumption and Coastal NIR Affects coastal and Shelf waters a) Produces Negative or “NO” nLw retrievals Greater in 410 , 443 , 488 b) Produces reduced values in “ certain areas ” c) Impacted the Aerosol (La) atmospheric correction removal d) Impacts - Lower nLw (radiances ) and Higher Chlorophyll values e) Accounts for differences of VIIRS and MODIS products f) Results in VIIRS not meeting Ocean requirements.
