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Developing NPP algorithms for the Arctic

Developing NPP algorithms for the Arctic. 1. Empirical chlorophyll based algorithm. Chukchi Sea. ANCOVA H 0 – means between light levels are equal. P < 0.00 , H 0 is rejected. 1. Empirical chlorophyll based algorithm. Chukchi Sea. 1. Empirical chlorophyll based algorithm. Resolute Bay.

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Developing NPP algorithms for the Arctic

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  1. Developing NPP algorithms for the Arctic

  2. 1. Empirical chlorophyll based algorithm Chukchi Sea

  3. ANCOVA H0 – means between light levels are equal P < 0.00 , H0 is rejected

  4. 1. Empirical chlorophyll based algorithm Chukchi Sea

  5. 1. Empirical chlorophyll based algorithm Resolute Bay

  6. ANCOVA H0 – means between light levels are equal P < 0.00 , H0 is rejected

  7. 1. Empirical chlorophyll based algorithm Resolute Bay

  8. 1. Empirical chlorophyll based algorithm Barents Sea

  9. 1. Empirical chlorophyll based algorithm Combined dataset

  10. ANCOVA H0 – means between regions are equal P < 0.00 , H0 is rejected

  11. 1. Empirical chlorophyll based algorithm Combined dataset Log PP = 1.36 + 1.0.LogChl • Average Chlorophyll • Resolute Bay 8.1 mg m-3 • Barents Sea 4.2 mg m-3 • Chukchi Sea1.2 mg m-3 • ANCOVA • Chl 0.8 – 32 mg m-3 • P < 0.01

  12. 1.1 Surface chlorophyll vs. Euphotic zone chlorophyll

  13. 1.1 Surface chlorophyll vs. Euphotic zone PP

  14. 1.1 Rrs vs. Euphotic zone PP

  15. 2. Model based on C:Chl ratios • Behrenfeld et al. (2005) developed a productivity model based on Chl:C ratios • and chlorophyll concentrations derived from ocean color satellite observations. • Carbon (POC) is retrieved from backscatter • Chlorophyll is retrieved from Rrs ratios (i.e OC4V4, OC3M or OC3Arc) • These are coupled with mixed layer light levels from surface PAR and K490 • observations and growth rates estimated from the literature. The final equation is: • NPP = C . µ . Zeu. h(Io) • Where C is carbon, µ is growth rate, Zeu is the euphotic depth and h(Io) describes how • changes in surface light influence the depth dependent profile • of carbon fixation

  16. 2. Model based on C:Chl ratios

  17. 2. Model based on C:Chl ratios • Model Input • Carbon (POC) is retrieved from backscatter – Behrenfeld global relationship • Chlorophyll is retrieved from Rrs ratios - OC3Arc • Surface PAR – estimated from observations • Mixed layer light levels – estimated from observations • Growth rate – literature global, 0.5 – 2 divisions d-1 • h(Io) taken from Behrenfeld and Falkowski (1997) • NPP = C . µ . Zeu . h(Io) • Model output • 1. NPP euphotic zone integrated - g C m-2 day-1

  18. 2.1 Results

  19. 2.1 Results – adjusted model

  20. 2.2 Sensitivity to model input

  21. 2.2 Sensitivity to model input

  22. 3.0 Comparison of both methods

  23. Surface Chlorophyll - Spring

  24. Surface Chlorophyll - Summer

  25. Surface chlorophyll - Fall

  26. Surface chlorophyll – Winter

  27. Surface PP - Spring

  28. Surface PP - Summer

  29. Surface PP - Fall

  30. Surface PP - Winter

  31. Kd PAR – Spring + Summer

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