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CUNY group recent activities and updates

CUNY group recent activities and updates. On going work on the validation of IDPS VIIRS OC data with LISCO’s SeaPRISM and NASA data . Preliminary results are shown (slide # 2 & 3).

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CUNY group recent activities and updates

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  1. CUNY group recent activities and updates • On going work on the validation of IDPS VIIRS OC data with LISCO’s SeaPRISM and NASA data. Preliminary results are shown (slide # 2 & 3). • Assessment of the impacts of the vicarious calibration gain changes on OC data retrievals in coastal areas (with NASA processing). • Recent recalibration of the LISCO SeaPRISM instrument at NASA showed only 0-1% deviation for all bands since the previous calibration in May 2011. • During regular maintenance and inspection, following the storm Sandy, SeaPRISM was slightly damaged and therefore had to be sent back to NASA for checkup and re-calibration. SeaPRISM operation will resume soon and HyperSAS is currently in operation.

  2. nLw(486nm) in mW/cm2/μm/sr 03/18/2012 01/09/2012 NASA NASA IDPS IDPS negative nLw values Masked with the value -999.5

  3. nLw(486nm) in mW/cm2/μm/sr 07/12/2012 • These IDPS VIIRS images are recently acquired from CLASS and therefore should reflect the most recent changes in the processing code. • Problems with exclusion of inland and coastal waters from processing and over-masking appear to persist. • Time-series and matchup comparison analysis are under way. • All figures shown this point forward are with NASA processing. NASA IDPS Masked with the value -999.5

  4. Time series of normalized water leaving radiance, nLw(λ) • nLw(λ) data of all sensors exhibit significant seasonal variations, but there is a reasonable agreement between the satellite mission and the SeaPRISM data for the 551nm wavelength. • However, the temporal agreements between the in-situ, and satellite nLw(λ) data are weak for LISCO site at 413nm wavelength.

  5. nLw (λ) match-up spectra of LISCO site • In the initial processing (VIIRSinitial), the vicarious calibration reference was derived from a sea surface reflectance model and a climatology of chlorophyll-a concentration. • In this latest processing (version 2012.2), the vicarious calibration is derived data from the Marine Optical Buoy (MOBY). • Evaluation of the VIIRS ocean color product has been carried out to assess the consistency of the overall calibration process. • Both VIIRSinitial and VIIRS12.2 exhibit close match in nLw spectral shapes and variation ranges to those of SeaPRISM and MODIS. • Nevertheless, average spectra of the VIIRS12.2 is slightly underestimated compared to that of SeaPRISM data. • VIIRS12.2 for LISCO site shows more frequent occurrences of the negative water leaving radiances especially at 413nm wavelength resulting in less number of spectra available for match up comparisons than VIIRSinitial.

  6. Qualitative analysis on VIIRS nLw (λ) data VIIRS12.2 SeaPRISM VIIRSinitial

  7. Matchup comparisons between nLw (λ) data of VIIRS and SeaPRISM for LISCO site • VIIRSinitial data achieves strong correlations at the wavelengths greater than 442nm: R values are equal to 0.8618, 0.9361 and 0.8276 at 491, 551 and 668nm respectively. However at 413 and 442nm correlations are weaker (R values are equal to 0.3 and 0.5832). • With VIIRS12.2 degradations in correlation with in-situ SeaPRISM data is observed at every wavelength. At 413 and 442nm correlation totally vanish. • On spectral average VIIRSinitial underestimates 22.6%. • With the VIIRS12.2, underestimations are further exacerbated to 26% and overall uncertainty is further amplified. More frequent occurrences of negative values retrieval in water leaving radiance data are also observed resulting in less number of available matchup spectra.

  8. Matchup comparisons between nLw (λ) data of VIIRS and MODIS for LISCO location • Overall consistency between the both VIIRS (VIIRS12.2& VIIRSinitial) and MODIS nLwdata. Strong correlation at every wavelength (R values range from 0.85 at 413nm to 0.99 at 551nm). • For the comparison with the VIIRSinitial, regression lines is very close to 1:1 line • However with VIIRS12.2, regression lines significantly deviate from 1:1 line and 25% underestimation in terms of the MODIS. • Uncertainties between the MODIS and VIIRSinitial data are very low (3.9%) at 551nm.

  9. Summary of statistical parameters • nLw(λ) data comparisons between the VIIRSinitial and in-situ SeaPRISM x and y are identified through the axis of the comparison figures of corresponding matchup analysis. • nLw(λ) data comparisons between the VIIRS12.2 and in-situ SeaPRISM • nLw(λ) data comparisons between the VIIRSinitial and MODIS • nLw(λ) data comparisons between the VIIRS12.2 and MODIS

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