Section G- Oceanography

The ocean covers what percentage of Earth’s surface?

71%

What do oceans regulate in the atmosphere?

chemical composition

_% of O₂ in atmosphere comes from photosynthesis in oceans

70

the ocean modifies earth’s _ and _ systems

climate, weather

½ of the world’s population depends directly on oceans as:

main food source

What are the names of the three light penetration zone?

1. Euphotic (sunlight) zone

2. Dysphotoic (twilight) zone

3. Aphotic (midnight) zone

Sunlight rarely penetrates beyond this zone, it is right below sea level

euphotic zone

In this zone, sunlight decreases rapidly with depth, below 200m

dysophotic zone

In this zone, sunlight does not penetrate at all, below 1000m

aphotic zone

In which zone does photosynthesis not exist?

dysphotic

Which zone is bathed in darkness?

aphotic

what is the percentage by weight of salts in seawater?

3.5%

what are the factors of salinity? (4)

• temperature

• evaporation

• precipitation

• freshwater input from rivers

ITCZ/ polar front: increase of rain → _ salinity

lower

SHPB: increase of evaporation → _ salinity

higher

Arctic ocean salinity is less (~30-35) due to: (3)

• fresh water from melting ice

• high precipitation, low evaporation

• emptying of major rivers into smaller Arctic Ocean

What is the average pH of the ocean?

8.16

What decreases seawater pH?

atmospheric CO₂ absorbed by seawater -→ carbonic acid (H₂CO₃)

What is the percentage increase in seawater acidity since industrial revolution?

30%

What is essential in sustaining global energy balance?

ocean currents

Ocean currents exchange _ between low and high latitudes

heat

What do ocean currents do?

moves water from one location to another

Oceanic currents are driven by: (5)

• wind

• density differences

• coriolis

• tides

• shape of ocean basins

What do ocean currents help move? (2) -warm and cool water

• warmer water moves towards the poles

• cooler water towards the equator

Which coast are warm currents located?

East

Which coast are cold currents located?

West

What are gyres?

large circular currents

What are the rotation of gyres dependent on? (3)

• wind patterns

• Coriolis effect impacting the surface currents

• arrangements of continents

gyres have _ western boundary current

strong

gyres have _ and broad eastern boundary current

weak

What are upwelling zone? (2)

• deep cold water rises to the surface

• west side of continents

Thermohaline circulation is circulation drives by: (3)

density differences temperature, and salinity