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