Patterns of Productivity• There is a large “SpringBloom” in the NorthAtlantic (temperatelatitudes… remember theGulf Stream!)Distribution of Solar EnergyThe tilt of the earth is critical!Heat FlowControlled by:• Blackbody Radiation• Angle of Incidence• Tilt of the earthGlobal Wind PatternsTrade WindsWesterliesPolar EasterliesWinds are caused bydifferences in Highsand LowsWind-Driven Currents• Dominated by theglobal wind patternsand the Coriolis Force• Very shallow…typically not more than100 m• Inefficient transfer ofenergy…typically 2-3%• Named for theDirection, as withwinds, but invertedOcean Climate ZonesSubtropical Gyres• Most of the basin is filled by the gyres• nutrient poor, warm waters • Formed by Western and Eastern Boundary CurrentsEkman TransportVorticity• Vorticity is the tendency to spin.• At the North or South Pole, you spin once every 24hours…at the Equator, you don’t spin at all.• As you move Northward, you gain more spin.Intensification of WesternBoundary CurrentsVorticity and Corioliscombine to for theGulf StreamStrong vorticitycauses weak easternboundary currentsMajor Currents• Dominated by:– Gyres– Wind PatternsVertical Circulation• Dominated by Thermohaline flow• Upwelling/Downwelling are special casesHenry Stommel--TheConveyor Belt ModelNutrient DistributionsExport Production Map“Phytoplankton are the blood of the sea” --- Victor Hensen“All fish is diatoms” --- Henry BigelowPatterns of ProductivityPatterns of ProductivityPatterns of ProductivityPatterns of Productivity• The Spring Bloom iscaused by:Physics-heat transport-seasonal stratification-lightChemistry-availability of nutrientsBiology-decoupling of grazersPhytoplanktonNutrientsZooplanktonhνLight in the OceanThe Marine EnvironmentSide ViewTop ViewTerrestrialMarineLightLight in waterL(z;ξ) = L(0;ξ)exp −1µc(z' ' )dz''0z∫      +1µL∗E(z' ;ξ) +1µc(z' )S(z' ;ξ)      0z∫× exp −1µc(z' ' )dz''z'z∫      dz'Rrs(λ) ≅LuEd= constantbbw+ bbpaw+ aph+ adm+ bbw+ bbpRadiative Transfer EquationBeer-Lambert LawE=E0 • e-kzLight: Particles and Waves• Light can be measured in terms of:• Energy (e.g. units of J m-2 s-1 or W m-2)– good for heat budgets and the like• Quanta (e.g. units of µmol quanta m-2 s-1)– useful for relating to photosynthesis or photochemical processes4.120nm)()smquantamol()s nm(10 vacuumain light ofspeed)(sfrequencys)J10(6.63constant sPlanck'photonsofnumber)J(energy/1221-191-34-⋅⋅⋅=⋅==⋅⋅=====−−−λµνελνεmWchnnhcnhThe atmosphere– The atmosphere attenuates the amount ofradiation impinging on earth’s surface.Kirk 1994, Fig. 2.1, p. 27AtmosphereSolar Radiation Incident on the Ocean• Transmission through the atmosphere depends on:• Solar zenith angle (latitude, season, time of day)• Cloud cover• Atmospheric pressure (air mass)• Water vapor• Atmospheric turbidity• Column ozone (important for UV-B)– Ground albedo (how much light is reflected from the ground) also affects theincident irradiance.• Midsummer Solar Irradiance at 45°N (midday)• about 450 W m-2 (PAR, energy units)• 2000 µmol m-2 s-1 (PAR, quanta)• Midwinter Solar Irradiance at 45°N• about 200 W m-2; 800 µmol m-2 s-1 ((PAR only)Note that “PAR” = Photosynthetically Available Radiation; it is the integral ofthe spectral irradiance over the visible wavelengths 400-700 nm.Solar irradiance at the air-sea interface• Surface Reflection– 2 - 3% for solar zenith angles 0° - 45°– Increased greatly when angles exceed 70°; less so with surfaceroughnessTotal internal reflectionFocusing and defocusingairwaterReflection and refraction• Refraction– Refractive index of natural waters is about 1.34 (air is 1.0)– Light direction becomes more vertical– Focusing and defocusing effects of wavesLight in the oceanLight in the oceanThe light becomes more directional and you lose the blues and the redsMore Units…The ABCs of LightAbsorption and Scattering Coefficientsare Inherent Optical Properties (IOPs)Absorbed (Heat)Incoming radiant powerTransmitted powerScattered powerLosses or attenuation from abeam are due to eitherabsorption or scattering. c = a + b,Where c is the beamattenuation, a the absorption,coefficient and b the scatteringcoefficient, all w/ dimensionsL-1.These terms are properties of the water and constituents;they do not vary with angular structure of the light field.But they do vary with the wavelength of light.Absorbed and re-emitted asfluorescence or RamanscatteringAbsorption, Scattering, andAttenuationAttenuation (c ) is the combination of absorption and scatteringDiffuse attenuation (k) isLight in the oceanAbsorption in the ocean00.10.20.30.40.50.60.7400 450 500 550 600 650 700Absorption (m-1)Wavelength (nm)WaterDetritus + dissolved colored matterTotalPhytoplanktonBlue water, green water…Scattering• Removal of photon from the incident light beam.– Forward scattering bf (m-1)– Backscattering bb (m-1)abfbbScattering in the oceanCoccolithophoreEmiliania huxleyihttp://earthguide.ucsd.edu/earthguide/imagelibrary/emilianiahuxleyi.htmlAbsorption plus ScatteringEddies off the coast of ChileRed tideOcean Color is a+bhttp://seawifs.gsfc.nasa.gov/SEAWIFS.htmlEven More Units…–Diffuse attenuation (K, m-1)• e.g., Kd (e.g. Ed (z+Δz) = Ed (z) exp(- Kd. Δz))–Reflectance (R)• e.g., Radiance reflectance (Lu/ Ed; sr-1)The Fundamentalproblem in ocean opticsis to relate the IOPs tothe AOPs….The diffuse attenuation coefficient arises because the underwaterlight field is not a collimated beam as is assumed when we talkabout the beam attenuation coefficient (c). It is useful however,because the diffuse attenuation coefficient, K, can describe theactual penetration of light in the sea. It is closely related to a.0.00 0.20 0.40 0.60 0.80 1.00Irradiance0.0020.0040.0060.0080.00100.00Depth (m)~ e-Kz~ 1%Optical Properties of the Sea:Sources of VariationIn the open ocean, the primary source of variation in absorption(a and K) is due to biological organisms, specificallyphytoplankton, which form the base of the marine food chain.The Secchi Disk:•First systematic usage reported in 1866, butobserved and remarked upon much earlier.•Early experiments carried out by CommanderCialdi, head of the Papal Navy, and ProfessorSecchi onboard the SS L’ImmacolataConcezione (Cialdi, 1866).•Used operationally for