Oceans

Question 1

How much of earths surface is covered by ocean

Answer 1

71%

Question 2

How much of earths water does oceans holds

Answer 2

97%

Question 3

What controls the climate and weather on earths surface?

Answer 3

The interactions between the oceans and atmosphere

Question 4

What are oceans responsible for?

Answer 4

Oceans are responsible for keeping conditions on the earth steady

Question 5

Name all 5 major oceans

Answer 5

• Pacific
• Atlantic
• Arctic
• India
• Southern ocean

Question 6

How can the effect of oceans on climate be measured

Answer 6

The effect of oceans on regional climates can be measured by comparing annual air temp at different latitudes

Question 7

What are the most important bathymetric features of the sea floor?

Answer 7

• Continental shelf - thinning continental crust
• Slope and rise - transition between crust types
• Abyssal plains
• Oceanic ridges
• Oceanic trenches

Question 8

How old is the ocean?

Answer 8

• Relatively young due to subduction of oceanic crust

- Oldest areas are ones furthest away from ridges

Question 9

What is the geology of the ocean crust?

Answer 9

• Formed at sea floor spreading ridges from magma
• 10% of the mantle rock melts producing magic magma
• 50% silica (forms pillow basalts, breccia and flows
• Beneath is gabbros - formed through the cooling of magma under the crust

Question 10

Describe oceanic sediment

Answer 10

• Thickness increases away from oceanic ridges
• Various sediment sources depending on the proximity to continent, water depth, currents, bio activity and climate
• Terrigenous - material eroded from land
• Pelagic - living organism shells - carbonate and silica
• Volcanic ash

Question 11

Where is oceanic sediment distributed?

Answer 11

• Terrigenous - close to continents - from deltas
• Red clay - located near shore environments
• Silica - southern polar regions and equator in pacific
• Carbonate - cannot be lower than 4000 as it will dissolve

Question 12

Why do humans retrieve deep sea sediment cores?

Answer 12

• Gives us information about the climate in the past

- Retrieved using drilling, majority of oceans have been drilled

Question 13

Why is sea salty?

Answer 13

The dissolved ions have been concentrated in sea water as a result of chemical weathering and the degassing of the mantle volcanic activity

Question 14

Why does salinity vary in the ocean?

Answer 14

surface waters evaporate, rain and stream water is added and ice forms and thaws

Question 15

What are the different depths of the ocean divided into?

Answer 15

Divided into areas based on temp and density

- all zones based on horizontal distance from continental plate

Question 16

How far does the sun penetrate into the ocean

Answer 16

only penetrates 200m of ocean water

Question 17

What is the photic zone?

Answer 17

• The top 200m of the ocean

- Important for marine wildlife

Question 18

What is the aphasic zone?

Answer 18

• Not enough light for photosynthesis

- Makes up majority of ocean water

Question 19

What are the 4 primary factors that control ocean circulation?

Answer 19

• Water salinity
• Water temp
• Surface winds
• Coriolis effect

Question 20

What is ocean circulation a major component of?

Answer 20

The climate system through the distribution of thermal energy

Question 21

What is surface ocean circulation primarily influenced by?

Answer 21

• Winds - controlled by atmospheric circulation

- Earths rotation

Question 22

What is thermohaline circulation (THC)

Answer 22

The movement of sea water in a pattern of flow dependent on variations in temperature, which give rise to changes in salt content and hence in density

Question 23

What is deep sea circulation primarily influenced by?

Answer 23

• Density (temp and salinity)

- Position of land masses

Question 24

What is the oceanic circulation system?

Answer 24

• Global conveyer
• Driven by changes in water temp and density
• surface flow of North Atlantic dominated by Gulf Stream
• Warm salty water driven northwards by prevailing winds
• Water cools and density increases and sinks near South Greenland
• This feeds the North Atlantic Deep Water (NADW)
• Current flows southwards to compensate for North flowing Gulf Stream
• Tother them comprise the Atlantic Meridional Overtiming Circulation (AMOC)

Question 25

Outline AMOC

Answer 25

- Water evaporates near tropics - E-W trade winds precipitate it init pacific - Salinity increases in Atlantic and decreases in pacific - Causes warm, salty Gulf Stream

Question 26

Outline NADW

Answer 26

- Surface water cools (denser) - Forms sea ice - becomes saltier (denser) - Sinks

Question 27

What are the stages of Broeckers (1990) Salt Oscillator Hypothesis?

Answer 27

- Injection of fresh water into N Atlantic reduces surface water density - sinking no longer takes place - AMOC slows down/shuts down - reduces northward heat transfer via Gulf Stream - Northern hemisphere ice sheets grow - salt content gradually increases (evaporation) as salty water is not removed from from the Atlantic - As salt accumulates, it gradually increases density until AMOC is able to start again - Positive feedback mechanisms

Question 28

What happens during times of NADW formation?

Answer 28

- Ice melting dilutes salinity of North Atlantic | - Eventually slowing or stopping NADW formation

Question 29

What happens when NADW does not form?

Answer 29

- Less salt removed and little heat transported north - Ice sheets stop melting - North Atlantic gets salty and NADW starts to form again