Upload
paris-trueman
View
217
Download
0
Tags:
Embed Size (px)
Citation preview
A Recipe for Ocean Productivity, with Variations
John MarraJohn MarraLamont-Doherty Earth ObservatoryLamont-Doherty Earth Observatory
Palisades, NYPalisades, NY
USAUSA
What I’m going to talk about An alternate (sort of) algorithm for An alternate (sort of) algorithm for
remotely-sensed primary remotely-sensed primary productivity productivity
Absorption and Pigments in Absorption and Pigments in phytoplankton, and in the phytoplankton, and in the algorithmalgorithm
Variations caused by mesoscale Variations caused by mesoscale phenomenaphenomena
An alternate (non-B&F) model of remotely-sensed primary
productivityP(z) = (E,N)a*ph [Chla(z)] E(z)
Agreement found between pigment and Agreement found between pigment and irradiance and irradiance and 1414C uptake in several studies C uptake in several studies
Coupled: based on absorption properties of Coupled: based on absorption properties of the ocean, and has some stabilitythe ocean, and has some stability
Allows for physiological adaptationAllows for physiological adaptation Challenge is to understand how quantum Challenge is to understand how quantum
yield and absorption vary with environmental yield and absorption vary with environmental propertiesproperties
Agreement found between calculations based on pigment and irradiance, with 14C uptake in different areas
0.01
0.1
1
10
0.01 0.1 1 10 100
C assim. (calculated)
C a
ssim
. (o
bse
rved)
Units: mmols C m-3 d-1
Boreal NA
Gulf of Maine
Sargasso Sea
Productivity Algorithm: What we need to know, minimum
Variability in Quantum Variability in Quantum Yield?Yield?
Chlorophyll-a as a Chlorophyll-a as a function of depth?function of depth?
Chlorophyll-specific Chlorophyll-specific absorption as a function absorption as a function of depth?of depth?
Spatial variability of Spatial variability of Chlorophyll-specific Chlorophyll-specific absorptionabsorption??
Function of irradiance; constant maximumFunction of irradiance; constant maximum
Gaussian (sub-surface Gaussian (sub-surface max) up to a thresholdmax) up to a threshold
Assumed constant with depth; Assumed constant with depth; averaged over averaged over
Varies with SST?Varies with SST?
Current version of the model
How the algorithm is (somewhat) stabilized and coupled.
Productivity
(Euphotic Depth)
Irradiance
Absorption
Chlorophyll
increasedecrease
increase
increase
decrease (all else
being equal)
increase
…but basing an algorithm on absorption means also knowing absorption from water and other components
Phytoplankton Absorption and Environmental Variables
Community composition
Environmental variables Absorption spectra
Absorption in Phytoplankton
Objective is to create rules for the geographic and Objective is to create rules for the geographic and temporal variability in a*temporal variability in a*ph ph (sensu Hoepffner and (sensu Hoepffner and Sathyendranath, 1992)Sathyendranath, 1992)
Avoid using relationships based on the [Chl-a] (e.g., Avoid using relationships based on the [Chl-a] (e.g., Bricaud et al., 1995; Cleveland, 1995) Bricaud et al., 1995; Cleveland, 1995) Up to now it seems that aUp to now it seems that a**
ph ph (() is only considered in ) is only considered in terms of the biological effects: pigment packaging and terms of the biological effects: pigment packaging and species composition, cell size.species composition, cell size.
Chlorophyll-a: as biomass, as an adaptable property, Chlorophyll-a: as biomass, as an adaptable property, as a trophic indicator?as a trophic indicator?
Assume that a*Assume that a*phph does not vary within the first two optical does not vary within the first two optical depths (literature supports, but not unanimous)depths (literature supports, but not unanimous)
How we might expect absorption properties to vary with SST
Absorption
Sea-Surface Temperature
a*p?
a*ph?
a*ps?
(Not a physiological relationship!)
Chlorophyll-specific absorption and SST
Sea Surface Temperature (ºC)
a*p
h (
m2 m
g c
hl-1
)
0.00
0.02
0.04
0.06
0.08
0.10
-5 0 5 10 15 20 25 30
Arabian SeaGulf of MaineMLML60NAESOPSGOMtotal pigmentPS pigment
(Marra and Trees, submitted)
PBopt and Temperature?
-1
1
3
5
7
9
11
13
15
-5 0 5 10 15 20 25 30 35
Temperature (ºC)
PBopt
[(m
gC
)(m
gC
hl)
-1 h
-1)]
(thanks to J. Cullen’s presentation at the Bangor Productivity Conference, March 2002)
(Based on physiology)
A Sample View of Algorithm Output: January, 1998
gC
m-2 d
-1
The Oceanic Mesoscale and Phytoplankton Variability
Two studies, two anti-cyclonic eddies, both Two studies, two anti-cyclonic eddies, both hemisphereshemispheres
Eddy Haulani off the island of HawaiiEddy Haulani off the island of Hawaii An eddy spawned by the Leeuwin Current (off An eddy spawned by the Leeuwin Current (off
W. Australia)W. Australia)
Vaillancourt, Marra, Bidigare, and Seki., submitted
The birth of the eddy, Haulani, near Hawaii I in Fall, 2000
Eddy Haulani as Ocean Color
Vaillancourt et al., submitted19 November, 2000(Dotted line indicates SST feature for same date)
SeaWiFS image, courtesy NASA GFSC and Orbital Sciences Corp.
Community composition in and out of the Hawaii eddy
Larger forms are found in greater numbers inside the eddy. (Picoplankton do not change much.)
Eddies in the Leeuwin Current
…Thomas Moore, LDEO and CSIRO, Hobart
The anti-cyclonic (“convergent”) eddy with the ocean color signal
From Moore et al., 2001
Anti-cyclonic eddy
We then compared the pigment composition of coastal water and that in the eddy….
Pigment analysis of coastal (Sta 52) and eddy (Sta 62) samples
Total quantity of pigment is the sameTotal quantity of pigment is the same Pigment composition nearly the same (loss of Pigment composition nearly the same (loss of
alloxanthin, fucoxanthin, Chl c1+c2)alloxanthin, fucoxanthin, Chl c1+c2)
Coastal Offshore eddy, 3 months later
From Moore et al., 2001
So, in conclusion… The Productivity Algorithm: promising, but needs workThe Productivity Algorithm: promising, but needs work
How does phytoplankton absorption vary with How does phytoplankton absorption vary with environmental properties?environmental properties?
What about other absorbing components?What about other absorbing components? Quantum yield parameterization?Quantum yield parameterization?
Non-absorption based observations (e.g., FRRF)Non-absorption based observations (e.g., FRRF) Environmental determinants to Environmental determinants to maxmax
Instead of PvsE parameters (like PInstead of PvsE parameters (like PBBoptopt), focus on a), focus on aphph and and
pigments pigments Go from satellite reflectances -> productivity?Go from satellite reflectances -> productivity? We need to understand the differences caused by We need to understand the differences caused by
vertical as opposed to horizontal processes in eddiesvertical as opposed to horizontal processes in eddies
Variations in Quantum Yield
Vaillancourt et al., in press, DSR II