Scales of importance from global to micro

Temporal Scales vary

Global currents

mesoscale

microscale

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 temp’s

• Flows in coherent bodies

Mechanisms for characteristics• Polarity of the water molecule

• Dissociation to H+ and OH-

Universal Solvent

“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

“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?

High Molecular Cohesion

High Viscosity, High Surface Tension

Consequences to Organisms?

consider small scale to large scale

coherence of water of similar temperature

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

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?)

Density + Coherence at small scale =

• segregation of water bodies at large scale