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Dariusz Stramski Marine Physical LaboratoryScripps Institution of OceanographyUniversity of California, San Diego
OCEAN OPTICS SCIENCE IN SUPPORT OF
QUANTITATIVE IMAGING OF COASTAL WATERS
COAST Meeting29 – 30 September 2004 - OSU, Corvallis OR
R() = f [ seawater constituents ]
≈ f [ bb() / a() ]
≈ f [ bb() / ( a() + bb() ) ]
= f [ a(), E(, ), I(, ’→ ) ]
R() = f [ IOPs() ]
IOPs() = f [ seawater constituents ]
Seawater is a complex optical medium with a great variety of particle types and soluble species
10 m
IOPd+CDOM() = IOPd() + IOPCDOM()
IOPp() = IOPph() + IOPd()
IOP() = IOPw() + IOPp() + IOPCDOM()
Three- or four-component model based on few broadly defined
seawater constituents
A three-component model of absorption
Chlorophyll-based models
IOPph() = f [ Chl ]
IOPp() = f [ Chl ]
IOP() = IOPw() + f [ Chl ]
Case 1 and Case 2 Waters
Morel and Prieur (1977); Gordon and Morel (1983)
• Average trends
• Large, seemingly random, variability
Clarke, Ewing and Lorenzen (1970)
Chlorophyll algorithms more than 30 years of history
Bricaud et al. (1998)
Beam attenuation vs chlorophyll
Loisel and Morel (1998)
Standard Chl algorithms in the Baltic Sea
Darecki and Stramski (2004)
Stagnation
Case1/Case 2 bio-optics
10
1
)( )(i
iiIOPIOP
Reductionist approachNew science strategy
Reductionist reflectance / IOP model
)()()(11
i
j
ii
j
ii NIOPIOP
Ni
])(,)(,),(,)([(1
,i1
,i1
,i1
,i
j
ibi
j
ibbi
j
ibi
j
iai NNNNfR
m
min m,IOP minerals)(
k
pla k,IOPIOP plankton )( )(p
n
det n,IOP detritus)(
j
bub j,IOP bubbles)(
EXAMPLE CRITERIA
• Manageable number of components
• The sum of components should account for the total bulk IOPs as accurately as possible
• The components should play a specific well-defined role in ocean optics, marine ecosystems, biogeochemistry, water quality, etc.
Example components ofsuspended particulate matter
Living ParticlesAutotrophs
1. Picophytoplankton <2 m2. Small nanophytoplankton 2-8 m3. Large nanophytoplankton 8-20 m4. Microphytoplankton 20-200 m
Heterotrophs5. Bacteria ~0.5 m6. Microzooplankton O(1-100) m
Non-Living ParticlesOrganic
7. Small colloids 0.02-0.2 m8. Larger colloids 0.2-1m9. Detritus >1m
Inorganic10. Colloidal/Clay minerals
<2m11. Larger (Silt/Sand) minerals
>2m
iii G Q )()( i
i
Ν
IOP )(
Stramski et al. (2001)
Interspecies variability in absorption
Stramski et al. (2001)
Interspeciesvariability inscattering
Stramski et al. (2001)
Intraspecies variability over
a diel cycle
Thalassiosira pseudonana
Stramski and Reynolds (1993)
Absorption of mineral particles
Babin and Stramski (2004); Stramski et al. (2004)
Asian mineral dust
Stramski and Wozniak (2004)
Scattering phase functions of bubbles
Piskozub et al. (2004)
Reductionist reflectance / IOP model
)()()(11
i
j
ii
j
ii NIOPIOP
])(,)(,),(,)([(1
,i1
,i1
,i1
,i
j
ibi
j
ibbi
j
ibi
j
iai NNNNfR
IOPmodel
Stramski et al. (2001)
Size distribution
Absorption Scattering
Absorption Backscattering
Radiative transfer model
Mobley and Stramski (1997)
The complexity of seawater as an optical medium should not deter us from pursuing the proper course in basic research to ensure quantitatively meaningful applications in coastal water imaging