Into the Abyss Flashcards

1
Q

How is the ocean stratified?

A

by density (warm and fresh= less dense than saline and cold)

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2
Q

what is the thermocline

A

thin layer in body of water where there is a rapid drop in temperature with depth

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3
Q

what is the pycnocline

A

thin layer where there is a rapid increase of density with depth

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4
Q

what is the dominant control on density

A

temperature

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5
Q

other than temperature, how can water change in density

A

exchanging of material to another body of water

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6
Q

explain the origins of salinity

A

streams carry dissolved substances to the sea-> made of cations from exposed crustal rock and anions likely from the mantle

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7
Q

how can the concentration of dissolved materials change?

A

addition or removal of freshwater due to rates of precipitation and evaporation

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8
Q

what is the halocline

A

a thin layer of water where there is a rapid change of salinity with depth

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9
Q

how can one track how two water masses mix with each other?

A

see how their characteristics change

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10
Q

give three depth layers in the ocean

A

surface zone/mixed layer, thermocline/halocline/pycnocline, deep zone

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11
Q

what percentage of the ocean’s volume is in the deep zone?

A

80%

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12
Q

at what latitudes is the deep zone in contact with the atmosphere?

A

high latitudes

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13
Q

to what depth is plant and animal life restricted?

A

200m (photic zone)

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14
Q

what is calcareous ooze and where can it be found

A

layers of muddy, calcium carbonate bearing soft rock sediment on the seafloor, low to mid latitudes

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15
Q

what organisms are favoured by warm surface water and why

A

carbonate secreting organisms, not found in deeper water due to acidity

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16
Q

name the largest body of polar surface water

A

antarctic circumpolar water, extends to the ocean floor

17
Q

roughly what depths are upper water masses at?

18
Q

where and how are deep and bottom water masses formed?

A

cold polar seas, cold winds cool water and cause it to sink

19
Q

how is north atlantic deepwater formed?

A

intense surface cooling and convective overturning-> becomes trapped in basins, overflows ridges and disperses

20
Q

how is antarctic bottom water formed?

A

cold winds and sea ice cool cool surface water as cold as possible without freezing, mixes with dense brine and sinks to deep ocean

21
Q

what is a gyre?

A

large subcircular ocean system made up of major ocean currents

22
Q

why is the centre higher than the periphery in the NA ocean gyre>

A

converging currents force it upwards

23
Q

explain the motion of currents in a gyre

A

coriolis effect and the pressure gradient balance and create a system in dynamic equilibrium so that water flows across rather than down the slope-> geostrophic currents

24
Q

what are warm and cold core rings?

A

meanders in currents like the gulf stream

25
by what measure is the speed of thermohaline circulation measured
metres per day
26
where do deep waters enter and leave the surface current system?
southern ocean
27
why would the breakdown of thermohaline circulation alter climate?
thermohaline circulation is an important transporter of heat
28
what determines the solubility of gas?
partial pressure: more soluble when water is cold, fresh and under high pressure
29
how are the oceans ventilated
oxygen rich water sinking
30
what gas is very soluble
CO2