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A Recipe for Ocean Productivity, with Variations

A Recipe for Ocean Productivity, with Variations. John Marra Lamont-Doherty Earth Observatory Palisades, NY USA. What I’m going to talk about. An alternate (sort of) algorithm for remotely-sensed primary productivity Absorption and Pigments in phytoplankton, and in the algorithm

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A Recipe for Ocean Productivity, with Variations

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  1. A Recipe for Ocean Productivity, with Variations John Marra Lamont-Doherty Earth Observatory Palisades, NY USA

  2. What I’m going to talk about • An alternate (sort of) algorithm for remotely-sensed primary productivity • Absorption and Pigments in phytoplankton, and in the algorithm • Variations caused by mesoscale phenomena

  3. An alternate (non-B&F) model of remotely-sensed primary productivity • Agreement found between pigment and irradiance and 14C uptake in several studies • Coupled: based on absorption properties of the ocean, and has some stability • Allows for physiological adaptation • Challenge is to understand how quantum yield and absorption vary with environmental properties P(z) = F(E,N)a*ph [Chla(z)] E(z)

  4. Agreement found between calculations based on pigment and irradiance, with 14C uptake in different areas Boreal NA Gulfof Maine C assim. (observed) Units: mmols C m-3 d-1 Sargasso Sea C assim. (calculated)

  5. Variability in Quantum Yield? Chlorophyll-a as a function of depth? Chlorophyll-specific absorption as a function of depth? Spatial variability of Chlorophyll-specific absorption? Productivity Algorithm: What we need to know, minimum Current version of the model Function of irradiance; constant maximum Gaussian (sub-surface max) up to a threshold Assumed constant with depth; averaged over l Varies with SST?

  6. How the algorithm is (somewhat) stabilized and coupled. increase Irradiance (Euphotic Depth) increase decrease decrease (all else being equal) Absorption Productivity increase increase Chlorophyll …but basing an algorithm on absorption means also knowing absorption from water and other components

  7. Phytoplankton Absorption and Environmental Variables research thus far Community composition Environmental variables Absorption spectra

  8. Absorption in Phytoplankton • Objective is to create rules for the geographic and temporal variability in a*ph (sensu Hoepffner and Sathyendranath, 1992) • Avoid using relationships based on the [Chl-a] (e.g., Bricaud et al., 1995; Cleveland, 1995) • Up to now it seems that a*ph (l) is only considered in terms of the biological effects: pigment packaging and species composition, cell size. • Chlorophyll-a: as biomass, as an adaptable property, as a trophic indicator? • Assume that a*ph does not vary within the first two optical depths (literature supports, but not unanimous)

  9. How we might expect absorption properties to vary with SST (Not a physiological relationship!) Absorption a*p? a*ph? a*ps? Sea-Surface Temperature

  10. Chlorophyll-specific absorption and SST a*ph (m2 mg chl-1) Sea Surface Temperature (ºC) (Marra and Trees, submitted)

  11. PBopt and Temperature? (Based on physiology) (thanks to J. Cullen’s presentation at the Bangor Productivity Conference, March 2002) PBopt [(mgC)(mgChl)-1 h-1)] Temperature (ºC)

  12. A Sample View of Algorithm Output: January, 1998 gC m-2 d-1

  13. The Oceanic Mesoscale and Phytoplankton Variability • Two studies, two anti-cyclonic eddies, both hemispheres • Eddy Haulani off the island of Hawaii • An eddy spawned by the Leeuwin Current (off W. Australia)

  14. The birth of the eddy, Haulani, near Hawaii I in Fall, 2000 Vaillancourt, Marra, Bidigare, and Seki., submitted

  15. Eddy Haulani as Ocean Color SeaWiFS image, courtesy NASA GFSC and Orbital Sciences Corp. 19 November, 2000 (Dotted line indicates SST feature for same date) Vaillancourt et al., submitted

  16. Community composition in and out of the Hawaii eddy Larger forms are found in greater numbers inside the eddy. (Picoplankton do not change much.)

  17. Eddies in the Leeuwin Current …Thomas Moore, LDEO and CSIRO, Hobart

  18. The anti-cyclonic (“convergent”) eddy with the ocean color signal

  19. We then compared the pigment composition of coastal water and that in the eddy…. Anti-cyclonic eddy From Moore et al., 2001

  20. Pigment analysis of coastal (Sta 52) and eddy (Sta 62) samples Coastal Offshore eddy, 3 months later • Total quantity of pigment is the same • Pigment composition nearly the same (loss of alloxanthin, fucoxanthin, Chl c1+c2) From Moore et al., 2001

  21. So, in conclusion… • The Productivity Algorithm: promising, but needs work • How does phytoplankton absorption vary with environmental properties? • What about other absorbing components? • Quantum yield parameterization? • Non-absorption based observations (e.g., FRRF) • Environmental determinants to Fmax • Instead of PvsE parameters (like PBopt), focus on aph and pigments • Go from satellite reflectances -> productivity? • We need to understand the differences caused by vertical as opposed to horizontal processes in eddies

  22. Variations in Quantum Yield Vaillancourt et al., in press, DSR II

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