Physical Oceanography

Collins

Oceanography

• Study of the Oceans• Oceanography is a interdisciplinary science. It

includes: Chemistry, Biology, and Physics.

History of Oceanography

• Oceanography began with the Challenger Expedition.

• We were able to find information about the seafloor and the ocean in general:– Ocean currents– Water temperature– Chemical Composition– Seafloor Sediments

Advanced Technology for the ocean

• Satellites continuously monitor the ocean such as the Topex/Poseidon which monitor the ocean’s temperatures.

• We have also been able to map the ocean floor using side-scan sonar.

• This method allows us to direct sound waves to the seafloor at an angle, so that the sides of underwater hills and other topographic features can be mapped.

The Oceans

• Earth actually contains one big ocean, however, Cartographers and Oceanographers list 4 major oceans.– Atlantic – Pacific– Arctic– Indian

Atlantic and Arctic Oceans

• The oceans are never fully frozen over.• They contain sheets of ice that cover them.• These two oceans also support a diversity of

life such as: Penguins, Polar Bears, seals, etc…

Tides

• In Saint John, Canada, the Bay of Fundy is famous for its’ dramatic daily tides.

• Tides are caused by the interaction of the Earth, sun, and moon.

• Tides-daily rise and fall of Earth’s waters on its coastlines

Why do tides occur?

• Tides occur because of the interaction of the sun, moon, and Earth.

• As the distance between objects increases, gravitational forces weaken.

• The moon pulls on the water on the side closest to it more strongly than it pulls on the center of the Earth and this creates a tidal bulge.

Daily Tide Cycle

• High tides occur about 12 hours and 25 minutes apart from each other.

• The height of tides can also be affected by islands and other landforms.

• Changes in the position of the Earth, Moon, and Sun affect the height of tides throughout the month.

Spring Tides

• Spring Tides—occur twice a month • We experience the highest high tides and the

lowest tides. • The term Spring tide comes from an old

English word called springen which means to jump.

• Spring tides occur during a Full Moon Phase and New Moon Phase.

Spring vs. Neap Tides

• Spring Tides-also occur when the Earth, sun, and moon are in a straight line.

• Neap Tides-occur when the moon is at a right angle to the sun

• Neap tides always occur between spring tides during a First Quarter and Third Quarter moon phase.

• We experience the highest low tides and the lowest high tides during Neap tides.

Energy from tides

• The movement of huge amounts of water between high and low tide are a source of potential energy

• Potential Energy-energy that is stored and waiting to be used.

• Tidal power plants have been designed to capture some of this energy as the tide moves in and out.

Chemical Properties of Ocean Water

• Ions-charged particles• Seawater is a solution of about 96.5% water

and 3.5% of dissolved salts.

Major Ions of Seawater

• Chloride…..19.35 ppt• Sodium……..10.76 ppt• Sulfate……….2.71 ppt• Magnesium…1.29 ppt• Calcium………..0.41 ppt• Potassium……..0.39 ppt• Bicarbonate……0.14 ppt• Bromide………0.067 ppt

Salinity

• Salinity—a measure of the amount of dissolved salts in seawater

• Units—ppt (parts per thousand)• The total salt content of seawater is typically

about 3.5% or 35 ppt.• Seawater also contains dissolved gases.

Dissolved gases in seawater

• Dissolved gases in seawater consist mainly of:– Oxygen – Nitrogen– Carbon Dioxide

Many dissolved nutrients also fill the ocean waters.

Variations in Salinity

• The average Salinity is 35 ppt.• Actual salinities vary from place to place.• Regions near the equator that have abundant

precipitation have lower salinities.• Areas where the rate of evaporation is very

high have higher salinities because the salt is left behind.

Removal of sea salts

• Salt ions are continuously added to seawater, the salinity although the salinity of the water does not increase.

• WHY????

Comparing densities

• What is the formula for density?

• Sea water has a higher density than freshwater.

• In other words, it is has a higher mass per unit of volume.

Physical Properties of the Ocean

• Freshwater has a maximum density of 1.00 g/cubic centimeter.

• Seawater is denser than freshwater.• Cold water is denser than warm water.• Freshwater freezes at 0 degrees Celsius, while

seawater will freeze at -2 degrees Celsius simply because salt ions interfere with the formation of hydrogen bonds.

Absorption of Light

• Water absorbs light. • In general, light will only go through

(penetrate) the first 100 m. of seawater.• Red light penetrates less than blue light

meaning that objects that are red that live or are below this zone will appear black. The same is true for blue objects that appear blue the zone for blue to penetrate.

Light absorption cont.

• Keep in mind that red objects are visible as red only until 10 m deep into the ocean. Blue objects appear blue until about 145 meters in the ocean. If objects that are blue appear below this zone, they appear black because wavelengths of light cannot reach that far into the ocean.

• Photosynthetic organisms can only live within the first 100 m. of the ocean.

Ocean Layering

• Ocean surface temperatures range from -2 to 30 degrees Celsius.

• Average surface temperature of the ocean is 15 degrees Celsius.

• Deep ocean water is always cold even in tropical oceans.

Temperature Profiles

• Temperature Profiles plot changing water temperatures with depth.

• Temperature profiles allow us to divide the ocean into three layers.– Surface layer (first 100 m)—warm, sunlit– Thermocline (rapidly decreasing temperatures

with depth)– Bottom layer (cold and dark with temperatures

near freezing)

Where does all this cold water come from?

• The source of the bottom, colder water is Earth’s polar seas.

• Higher salinities and colder temperatures cause seawater to become more dense.

• When seawater freezes near the Arctic and Antarctic, the salt does not freeze.

• The salt sinks in the underlying waters causing the salinity of this water to increase and this water migrates towards the equator.

What can cause an ocean wave to break?

• Ocean waves that are approaching shallow water begin to lose energy due friction with the bottom of the ocean.

• When ocean waves begin to “break”, the distance from crest to crest will decrease.

Ocean Currents

• Density Currents-caused by differences in the temperature and salinity of ocean water which in turn can affect density

• These are underwater currents that move slowly in deep ocean waters.

Surface Currents

• Waves in the ocean are driven by wind.• Surface Currents-affect mainly the upper few

hundred kilometers of the ocean • Surface currents are driven by the global wind

systems.

Gyres

• If Earth were totally an ocean, we would only experience simple belts of easterly and westerly currents.

• Since continents are present, they deflect ocean currents to the north and the south so that closed current circular systems (gyres) develop.

Upwelling

• Ocean waters moves horizontally, but also vertically.

• The upward motion of ocean water is called upwelling.

• Upwelling waters come from the bottom of the ocean and are cold.

• This occurs because trade winds blow surface water offshore and deep, colder water rises to the surface.

Physical Oceanography

Collins

Oceanography

• Study of the Oceans• Oceanography is a

_____________________________ science. It includes: Chemistry, Biology, and Physics.

History of Oceanography

• Oceanography began with the _____________ Expedition.

• We were able to find information about the seafloor and the ocean in general:– Ocean currents– Water temperature– Chemical ________________– Seafloor _________________

Advanced Technology for the ocean

• Satellites continuously monitor the ocean such as the ___________/Poseidon which monitor the ocean’s temperatures.

• We have also been able to map the ocean floor using _________________________.

• This method allows us to direct sound waves to the seafloor at an angle, so that the sides of underwater hills and other _______________ features can be mapped.

The Oceans

• Earth actually contains one big ocean, however, Cartographers and Oceanographers list 4 major oceans.– Atlantic – Pacific– Arctic– Indian

Atlantic and Arctic Oceans

• The oceans are ___________ fully frozen over.• They contain sheets of ice that cover them.• These two oceans also support a

_____________ of life such as: Penguins, Polar Bears, seals, etc…

Tides

• In Saint John, Canada, the ________________ is famous for its’ dramatic daily tides.

• Tides are caused by the _________________ of the Earth, sun, and moon.

• _____________-daily rise and fall of Earth’s waters on its coastlines

Why do tides occur?

• Tides occur because of the interaction of the sun, moon, and Earth.

• As the distance between objects ____________, gravitational forces weaken.

• The moon pulls on the water on the side closest to it more strongly than it pulls on the center of the Earth and this creates a _______________________________.

Daily Tide Cycle

• ______________ tides occur about 12 hours and 25 minutes apart from each other.

• The height of tides can also be affected by islands and other landforms.

• Changes in the _____________ of the Earth, Moon, and Sun affect the height of tides throughout the month.

Spring Tides

• __________________—occur twice a month • We experience the highest high tides and the

lowest tides. • The term Spring tide comes from an old

English word called springen which means to jump.

• Spring tides occur during a ____________ Phase and ________________ Phase.

Spring vs. Neap Tides

• Spring Tides-also occur when the Earth, sun, and moon are in a straight line.

• ______________________-occur when the moon is at a right angle to the sun

• Neap tides always occur between spring tides during a _________________ and _______________________ moon phase.

• We experience the highest low tides and the lowest high tides during Neap tides.

Energy from tides

• The movement of huge amounts of water between high and low tide are a source of __________________ energy

• Potential Energy-energy that is __________ and waiting to be used.

• Tidal _______________ plants have been designed to capture some of this energy as the tide moves in and out.

Chemical Properties of Ocean Water

• ____________-charged particles• Seawater is a solution of about __________

water and ___________ of dissolved salts.

Major Ions of Seawater

• ______________…..19.35 ppt• ______________……..10.76 ppt• Sulfate……….2.71 ppt• Magnesium…1.29 ppt• Calcium………..0.41 ppt• Potassium……..0.39 ppt• Bicarbonate……0.14 ppt• Bromide………0.067 ppt

Salinity

• _______________—a measure of the amount of dissolved salts in seawater

• Units—ppt (__________________________)• The total salt content of seawater is typically

about 3.5% or 35 ppt.• Seawater also contains dissolved gases.

Dissolved gases in seawater

• Dissolved gases in seawater consist mainly of:– _________________________– _________________________– Carbon Dioxide

Many dissolved nutrients also fill the ocean waters.

Variations in Salinity

• The average Salinity is ______________.• ____________ salinities vary from place to

place.• Regions near the equator that have abundant

precipitation have ______________ salinities.• Areas where the rate of evaporation is very

high have higher salinities because the salt is left behind.

Removal of sea salts

• Salt ions are continuously added to seawater, the salinity although the salinity of the water does not increase.

• WHY????

Comparing densities

• What is the formula for density?

• Sea water has a _____________ density than freshwater.

• In other words, it is has a higher mass per unit of volume.

Physical Properties of the Ocean

• Freshwater has a maximum density of 1.00 g/cubic centimeter.

• Seawater is ______________ than freshwater.• Cold water is ____________than warm water.• Freshwater freezes at 0 degrees Celsius, while

seawater will freeze at -2 degrees Celsius simply because salt ions interfere with the formation of _____________________ bonds.

Absorption of Light

• Water absorbs light. • In general, light will only go through

(penetrate) the first ________ m. of seawater.• Red light penetrates less than blue light

meaning that objects that are red that live or are below this zone will appear _________. The same is true for blue objects that appear blue the zone for blue to penetrate.

Light absorption cont.

• Keep in mind that red objects are visible as red only until 10 m deep into the ocean. Blue objects appear blue until about 145 meters in the ocean. If objects that are blue appear below this zone, they appear black because wavelengths of light cannot reach that far into the ocean.

• _________________________organisms can only live within the first 100 m. of the ocean.

Ocean Layering

• Ocean surface temperatures range from -2 to 30 degrees Celsius.

• Average surface temperature of the ocean is ________ degrees Celsius.

• Deep ocean water is always cold even in _______________ oceans.

Temperature Profiles

• Temperature Profiles plot changing water temperatures with depth.

• Temperature profiles allow us to divide the ocean into three layers.– ________________ layer (first 100 m)—warm, sunlit– ________________ (rapidly decreasing

temperatures with depth)– ________________ (cold and dark with

temperatures near freezing)

Where does all this cold water come from?

• The source of the bottom, colder water is Earth’s polar ______________.

• _________________ salinities and colder temperatures cause seawater to become more dense.

• When seawater freezes near the Arctic and Antarctic, the salt does not freeze.

• The salt sinks in the underlying waters causing the salinity of this water to increase and this water migrates towards the _________________.

What can cause an ocean wave to break?

• Ocean waves that are approaching shallow water begin to lose energy due to __________________ with the bottom of the ocean.

• When ocean waves begin to “break”, the distance from crest to crest will ______________.

Ocean Currents

• ____________________-caused by differences in the temperature and salinity of ocean water which in turn can affect density

• These are underwater currents that move slowly in deep ocean waters.

Surface Currents

• Waves in the ocean are driven by __________.• ________________ Currents-affect mainly the

upper few hundred kilometers of the ocean • Surface currents are driven by the global wind

systems.

Gyres

• If Earth were totally an ocean, we would only experience simple belts of easterly and westerly currents.

• Since _________________ are present, they deflect ocean currents to the north and the south so that __________________ current circular systems (gyres) develop.

Upwelling

• Ocean waters moves horizontally, but also ___________________.

• The upward motion of ocean water is called _____________________.

• Upwelling waters come from the bottom of the ocean and are ____________.

• This occurs because trade winds blow _______________ water offshore and deep, colder water rises to the surface.