test 3 marine science

[Ocean Structure] What three properties affect seawater density?

Temperature, salinity, and pressure (depth).

[Ocean Structure] What happens to density as temperature decreases?

Density increases.

[Ocean Structure] What happens to density as salinity increases?

Density increases.

[Ocean Structure] What happens to density as pressure increases?

Density increases.

[Ocean Structure] In general, what type of water sinks?

Colder, saltier, denser water.

[Ocean Structure] What are the three main vertical temperature layers?

Surface mixed layer, thermocline, and deep layer.

[Ocean Structure] What is the approximate depth of the surface mixed layer?

0-about 100 m.

[Ocean Structure] What characterizes the surface mixed layer?

It is well-mixed, with relatively uniform properties near the surface.

[Ocean Structure] What is the thermocline?

A layer where temperature changes rapidly with depth.

[Ocean Structure] What is the approximate depth range of the thermocline in the typical profile?

About 100-1,000 m.

[Ocean Structure] What characterizes the deep temperature layer?

Below about 1,000 m, temperature is relatively cold and constant.

[Ocean Structure] What does isothermal mean?

Having the same temperature; at depth, the ocean is approximately isothermal.

[Ocean Structure] What is stratification?

The arrangement of ocean water into layers.

[Ocean Structure] At what latitudes is a permanent thermocline observed?

Low latitudes.

[Ocean Structure] What thermoclines are found at mid-latitudes?

A seasonal thermocline and a permanent thermocline.

[Ocean Structure] What is the typical temperature profile at high latitudes?

Temperature is relatively uniform with depth, with little or no thermocline.

[Ocean Structure] During what season is the mid-latitude mixed layer deepest?

Winter.

[Ocean Structure] What happens to the mixed layer during fall at mid-latitudes?

The mixed layer deepens.

[Ocean Structure] What happens to the temperature profile during summer at mid-latitudes?

Surface warming creates a shallow seasonal thermocline.

[Ocean Structure] What is the halocline?

A layer where salinity changes rapidly with depth.

[Ocean Structure] What is the approximate depth of the halocline in the lecture profile?

Around 1,000 m.

[Ocean Structure] How does salinity generally change with depth at high latitudes?

It generally increases with depth.

[Ocean Structure] How does salinity generally change with depth at low latitudes?

It generally decreases with depth.

[Ocean Structure] What happens to salinity below about 1,000 m?

It is relatively constant.

[Ocean Structure] What is the pycnocline?

A layer where density changes rapidly with depth.

[Ocean Structure] What happens to density from about 100-1,000 m?

Density increases with depth in the pycnocline.

[Ocean Structure] What characterizes density below about 1,000 m?

It is relatively homogeneous.

[Ocean Structure] What is a stable water column?

A water column in which density increases with depth.

[Ocean Structure] Does a stable water column have denser water near the surface?

No. It has denser water at greater depth.

[Ocean Structure] What does a T-S diagram compare?

Temperature and salinity to determine or compare seawater density.

[Ocean Structure] What does T stand for on a T-S diagram?

Temperature.

[Ocean Structure] What does S stand for on a T-S diagram?

Salinity.

[Ocean Structure] What are isopycnals?

Lines connecting points of equal density.

[Ocean Structure] Can different temperature and salinity combinations produce the same density?

Yes. Different water masses can have equal density.

[Ocean Structure] What is the symbol for density?

Rho (ρ).

[Ocean Structure] What is the density index called and what is its symbol?

Sigma (σ), also called the density index.

[Ocean Structure] What is the density conversion formula from the lecture?

ρ = 1 + (σ / 1000).

[Ocean Structure] If σ = 25, what is density?

ρ = 1 + 25/1000 = 1.025 g/cm³.

[Ocean Structure] What two properties determine the density of water masses in the Exam 3 practice question?

Temperature and salinity at the surface.

[Ocean Structure] What is a water mass?

A large body of water with distinct characteristics.

[Ocean Structure] Where do water masses form?

At the ocean surface.

[Ocean Structure] What determines how water masses sink?

Their density; denser water sinks beneath less-dense water.

[Ocean Structure] What can water masses do at depth?

They may mix or displace one another.

[Ocean Structure] What is caballing?

Water masses of different densities mix slowly without an input of energy.

[Ocean Structure] What is surface water in the water-mass depth zones?

0-200 m.

[Ocean Structure] What is intermediate water in the water-mass depth zones?

About 300-2,000 m.

[Ocean Structure] What is deep water in the water-mass depth zones?

About 2,000-4,000 m.

[Ocean Structure] What is bottom water in the water-mass depth zones?

Deeper than 4,000 m.

[Ocean Structure] What does NADW stand for?

North Atlantic Deep Water.

[Ocean Structure] What are the lecture characteristics of NADW?

About 2-3°C and 35 psu; low nutrients and high oxygen near its source.

[Ocean Structure] What does AABW stand for?

Antarctic Bottom Water.

[Ocean Structure] What are the lecture characteristics of AABW?

About −0.5°C to 0.3°C and 34.7-34.8 ppt.

[Ocean Structure] What are the lecture characteristics of Antarctic Intermediate Water (AAIW)?

About 5°C and 34.8 ppt.

[Ocean Structure] What are the lecture characteristics of Mediterranean Intermediate Water?

About 13°C and 37-38 ppt.

[Ocean Structure] What is Circumpolar Deep Water in the lecture?

A mixture of NADW and AABW that becomes deep water in the Indian and Pacific.

[Ocean Structure] What is distinctive about Atlantic water masses?

The Atlantic has distinct water masses, including NADW and AABW.

[Ocean Structure] What is distinctive about Pacific deep water?

Layers are harder to distinguish; temperature and salinity are relatively uniform below 2,000 m.

[Ocean Structure] What is distinctive about the Indian Ocean?

It is principally a Southern Hemisphere ocean and has a lens of warm, salty surface water at tropical latitudes.

[Ocean Structure] What is distinctive about the Arctic Ocean's density?

Density is controlled more by salinity than by temperature.

[Ocean Structure] What are the three terms for rapid changes in ocean profiles?

Thermocline = temperature; halocline = salinity; pycnocline = density.

[Circulation] What is density-driven circulation also called?

Thermohaline circulation.

[Circulation] What causes thermohaline circulation?

Density variations caused by differences in temperature and salinity.

[Circulation] What is the ocean conveyor belt?

The global movement of ocean water associated with thermohaline circulation.

[Circulation] What happens to warm surface water in the density-driven circulation model?

It moves from the equator toward the poles, cools, becomes denser, and sinks.

[Circulation] What is continuity of flow?

The amount of water that sinks must equal the amount of water that rises because ocean water is a fixed quantity.

[Circulation] What is the role of winds in ocean circulation?

Winds are also needed to mix the oceans.

[Circulation] What does thermohaline circulation transport?

Large amounts of heat, affecting regional climates.

[Circulation] What does AMOC stand for?

Atlantic Meridional Overturning Circulation.

[Circulation] What does AMOC do?

It circulates Atlantic water, bringing warmer water north toward the poles and colder water south toward the equator.

[Circulation] How does AMOC affect climate?

It helps regulate global climate.

[Circulation] About how long does the lecture estimate for 1 cm³ of water to travel along the conveyor belt?

About 1,000 years.

[Circulation] How could warming disrupt thermohaline circulation?

Melting sea ice can make the North Atlantic fresher and less salty.

[Circulation] Why might warmer, fresher water disrupt deep-water formation?

It is less dense and may not sink and circulate through the deep ocean as it currently does.

[Circulation] What did the cited model predict if thermohaline circulation completely collapsed?

Drastic Northern Hemisphere cooling within 20-30 years; circulation could re-establish by about 100 years after collapse.

[Circulation] Besides winds, what other process helps mix the oceans?

Tides, which generate internal waves between water masses.

[Circulation] What ocean depth range do winds affect in the lecture?

The upper approximately 1,000 m.

[Circulation] What can wind-driven mixing produce?

Surface and internal waves, turbulent mixing, upwelling, and downwelling.

[Circulation] What is the Coriolis effect?

The apparent deflection of moving air and water due to Earth's rotation.

[Circulation] Which way does the Coriolis effect deflect motion in the Northern Hemisphere?

To the right.

[Circulation] Which way does the Coriolis effect deflect motion in the Southern Hemisphere?

To the left.

[Circulation] How fast are surface currents compared with the wind?

About 1/100 of the wind speed measured 10 m above the sea surface.

[Circulation] What is an Ekman spiral?

A pattern in which each deeper water layer moves more slowly and is deflected relative to the layer above.

[Circulation] What is Ekman transport?

The net movement of water 90° to the right or left of the wind direction.

[Circulation] In which direction is Ekman transport deflected in the Northern Hemisphere?

90° to the right of the wind direction.

[Circulation] In which direction is Ekman transport deflected in the Southern Hemisphere?

90° to the left of the wind direction.

[Circulation] What is upwelling?

Divergence or separation of water masses, allowing deeper water to rise.

[Circulation] What type of water rises during upwelling?

Cold, dense, nutrient-rich deep water.

[Circulation] Why does upwelling support high productivity?

It brings nutrients toward the surface, supporting photosynthesis.

[Circulation] What is downwelling?

Convergence of water masses; surface waters move together and sink.

[Circulation] What does downwelling transport to deeper water?

Oxygen-rich surface water.

[Circulation] What typically causes upwelling and downwelling?

Wind-driven surface currents.

[Circulation] What is a gyre?

A large, circular, wind-driven current system.

[Circulation] Which direction do gyres rotate in the Northern Hemisphere?

Clockwise.

[Circulation] Which direction do gyres rotate in the Southern Hemisphere?

Counterclockwise.

[Circulation] What are the five major ocean gyres?

North Pacific, South Pacific, North Atlantic, South Atlantic, and Indian Ocean gyres.

[Circulation] What forces are balanced in geostrophic flow?

Gravity (pressure-gradient force) and the Coriolis effect.

[Circulation] How does a mound of water form in the center of a gyre?

Ekman transport builds up a lens or mound of water, up to about 2 m above sea level.

[Circulation] What is western intensification?

The peak of gyre currents occurs closer to the western side of the ocean basin.

[Circulation] What are western boundary currents like?

Fast, narrow, and deep.

[Circulation] What are mesoscale eddies?

Meanders that pinch off from large boundary currents such as the Gulf Stream.