The Pew Oceans Commission

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Scales of importance from global to micro
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Temporal Scales vary
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Global currents
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mesoscale
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microscale
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What do we need to know about the basic
characteristics of sea water?

• Important phenomena
• Dissolves many compounds
• Heats and cools more slowly than land masses
• Remains liquid over a large range of temps
• Flows in coherent bodies

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Mechanisms for characteristics

• Polarity of the water molecule
• Dissociation to H and OH-

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Universal Solvent
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Salinity

• 3.5 of seawater is dissolved substances
• Chloride Sodium (85.65 of d.s.)
• Magnesium Sulfate (11.37 of d.s.)
• Calcium Potassium (2.26 of d.s.)
• Other important, but rarer, components
• bicarbonate, bromide, boric acid, iron, strontium

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Saline or Haline?

• PSU (practical salinity units)
• Parts per thousand
• 3.5 equals 35 psu
• But accurate measurements use conductivity
  relative to a standard
• Why is salty inland water different than
  seawater?

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High Molecular Cohesion

• High Viscosity, High Surface Tension
• Consequences to Organisms?
• consider small scale to large scale

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coherence of water of similar temperature
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High Heat capacity

• Combination of slower evaporation at high
  temperatures, and large amount of heat gained
  when changing from solid to liquid
• Sea water changes temperature slowly

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Temperature salinity affect water density

• Highest density of ocean water -1.9 C
• (pure water highest density is 4 C, so ice
  floats)
• Very cold ocean water sinks
• promotes circulation between surface and depths
• most ocean is open water at surface (important
  for gas exchange)
• Ocean ice floats (why?)

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Density Coherence at small scale

• segregation of water bodies at large scale