Oceans: Temperature, Composition, Structure, & Currents

Sea Surface Temperature Varies from north to south due to the Sun’s radiation Band of warm water shifts with seasons Northward – JJA and Southward – DJF

Sea Surface Temperature Variations in Incoming Solar Radiation  Intensity of Solar heating Variations in Incoming Solar Radiation  Intensity of Solar heating –Tilt of the Earth –Thickness of atmosphere Solar Rays perpendicular to Earth’s surface  Most Intense Heating Solar Rays perpendicular to Earth’s surface  Most Intense Heating –Equator –Tropics of Cancer & Capricorn Solar Rays at lower angles  Least Intense Heating Solar Rays at lower angles  Least Intense Heating –Polar regions

Variations in Sun’s rays with latitude

The Ocean is layered: Surface water Surface water –Salty due to evaporation –Warmer – solar radiation Middle Middle –Cold –Salty Dense bottom water Dense bottom water –Cold

Ocean basins Temperature variations within ocean basins

Salinity of Seawater Water is polar – Water is polar – –O is (-) and attracted to (+) charged particles CATIONS –H are (+) and attracted to (-) charged particles ANIONS The cation sodium attaches to the negative side The cation sodium attaches to the negative side The anion chlorine attaches to the positive side The anion chlorine attaches to the positive side The figure illustrates dissolved salt The figure illustrates dissolved salt

In 1000 grams of seawater…

Source of salts? Chemical weathering of rocks (dissolved load) Volcanic activity: outgassing

Why is the ocean blue? Intensity of water at different depths Intensity of water at different depths Absorptions is greater for longer wave lengths-red Absorptions is greater for longer wave lengths-red Ocean is blue Ocean is blue Most of the light is absorbed in the few meters of water Most of the light is absorbed in the few meters of water

Factors that affect SALINITY-

Fig. 16.4, p.402

Precipitation and Evaporation Red-precipitation Blue-evaporation

Density = mass/volume What factors change the density of sea water? What factors change the density of sea water? As temperatures increase, density decreases As salinity increases, density increases

Density and Ocean Structure

Coriolis effect: earth’s rotation causes gyres rotation

Gyres or circular patterns in the oceans create currents

The Gulf Stream How Benjamin Franklin described it in 1770: How satellites see it:

Air Temperature is influenced by ocean currents.

Ocean currents influence climate

Upwelling Wind blows water away from shore Wind blows water away from shore Cold nutrient-rich water is “pulled” to the surface Cold nutrient-rich water is “pulled” to the surface

Nutrients are produced by bacterial decay of material Nutrients are produced by bacterial decay of material Phosphates, nitrates, carbonates Phosphates, nitrates, carbonates Provide nutrients for plankton (base of the food chain) Provide nutrients for plankton (base of the food chain) Upwelling: bottom waters are nutrient rich

Upwelling: where

Upwelling: significance Supplies basic nutrients for single-celled organisms Supplies basic nutrients for single-celled organisms Diatoms (plants) Diatoms (plants) Offshore Ireland Offshore Ireland Coast of California Coast of California Red: highest concentration