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Lisl Robertson, University of Cape Town, RSA with assistance from Stewart Bernard Christo Whittle

GOOS AFRICA. Lisl Robertson, University of Cape Town, RSA with assistance from Stewart Bernard Christo Whittle. Preliminary Validation and Application of the Globcolour Products in the Benguela System. HABs in the Southern Benguela: in situ and satellite monitoring activities

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Lisl Robertson, University of Cape Town, RSA with assistance from Stewart Bernard Christo Whittle

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  1. GOOS AFRICA Lisl Robertson, University of Cape Town, RSA with assistance from Stewart Bernard Christo Whittle

  2. Preliminary Validation and Application of the Globcolour Products in the Benguela System • HABs in the Southern Benguela: in situ and satellite monitoring activities • Preliminary Qualitative Globcolour spectral validation • Globcolour Regional experiments: Benguela System and • Subtropical Convergence • Marine Remote Sensing Unit: data provision to Africa

  3. HABs and the Southern Benguela

  4. BOB: HAB Monitoring Buoy Satellite Monitoring • BOB Instrumentation • Two hyperspectral radiometers • 30 m digital thermistor chain • Fluorometer • ADCP • Satellites: • Near real time reception of daily 1 km MERIS data directly from ESA via local DDS • Archived reception of 250 m MERIS data on request • Locally processed AVHRR sea surface temperature and MODIS data through UCT Remote Sensing Unit Moorings: multi-sensor lightweight coastal buoys allowing high frequency point sampling with real time data on demand. Mooring system supplied real time data from January 2005 until April 2007.

  5. Multi-Scale Observation of HAB Events: Summer 2005 A B C March 30th: small Prorocentrum triestinum dominated assemblage April 2nd: low biomass waters April 5th : large Ceratium furca dominated assemblage

  6. Remote Sensing Reflectance Spectra: BOB vs Globcolour 050201: high biomass diatoms, Chlorophyll a ~ 10 050422: massive dinoflagellate bloom, Chlorophyll a ~ 50 050428: chlorophyll a estimated 5 – 10 Typical “background” signal in bloom season 050517: very odd spectrum…

  7. Remote Sensing Reflectance Spectra: BOB vs Globcolour: focus on 531 nm band 050227 050508 050510 060309 531 may be problematic in high biomass, but could also be sensitive to phycoerythrin peak – further investigation required

  8. Remote Sensing Reflectance Spectra: BOB vs Globcolour: focus on 510 nm band 060312 060319 Little mystery: one week in 2006 – 510 nm band failed. But look how well Globcolour performs in the blue …

  9. Globcolour, BOB Remote Sensing Reflectance Comparisons • 412 nm expected to perform worst • 531 nm has some accurate matches but many outliers as has been seen • Best performing bands at 620, 670 and 709 nm, with a slight general overestimation by Globcolour (also by MERIS). But Globcolour not fully normalised at 709 … unclear effect on RRS?

  10. GlobColour Comparative Products: Southern Africa and Southern Ocean GlobColour Weighted Chl 1 GlobColour GSM Chl 1 GlobColour Experimental Benguela Chl SeaWiFS OC4 Chl

  11. Analytical reflectance algorithms: size distributions of two layered spheres Chloroplast Cytoplasm The analytical reflectance algorithm is based on the representation of the optical properties of algal cells using two layered spheres, using Standard particle size distributions to simulate polydispersed natural algal populations. This allows better estimates of algal biomass (Chl a), and biomass independent assemblage descriptors: mean algal size (Deff) and physiological/algal group proxies (fluorescence quantum yield). An analytical algorithm also allows analogous application to both buoy and satellite ocean colour measurements. Simulated effects of changing chlorophyll concentration, effective algal diameter, and assemblage type on the reflectance spectrum

  12. GlobColour Experimental Products: Southern Africa and Southern Ocean Experimental reflectance/fluorescence inversion algorithms Fluorescence line height and quantum yield products allow some assessment of algal biomass and physiological variability. Algal effective diameter is used to assess biomass specific assemblage variability e.g. HABs in the Benguela, carbon export in the sub-tropical convergence zone Algal Fluorescence Line Height Algal Effective Diameter Algal Fluorescence Quantum Yield Non Algal Backscattering GSM Particulate Backscattering

  13. Marine Remote Sensing: Developing an Operational Capability Near Real Time: MODIS various MERIS various AVHRR SST MSG-2 SST Archive/Climate 10 yr colour, 15 yr altimetry, 20 yr+ winds, 20 yr+ temperature Higher Level Interoperable with other sites for integrated products New MRSU and GEO/GOOS ChloroGIN site to be launched November 2007

  14. Validation and protocols for high biomass studies • Algorithm validation and development • Ecological use of Globcolour in regional systems

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