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Music today: Little Mermaid,

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Music today: Little Mermaid, 'Under the Sea' WELCOME OSU MOMS!! Deep Ocean Circulation ... How does the Deep Ocean respond to Surface Circulation? The main ... – PowerPoint PPT presentation

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Title: Music today: Little Mermaid,


1
Music today Little Mermaid, Under the
SeaWELCOME OSU MOMS!!
2
Deep Ocean Circulation
  • Motion in the Ocean, Part 2, or
  • Who wants to ride the Great Conveyor Belt?

3
Surface Circulation
4
How does the Deep Ocean respond to Surface
Circulation?
  • The main gyres move heat and salt
  • Resulting DENSITY variations lead to vertical
    flow (sinking)
  • Formation of water masses, characterized by
    Temperature, Salinity

5
Density Variation in Sea Water
Isopycnals constant density
6
North Atlantic Circulation
7
Density-Driven Water Flow
  • Called Thermohaline Circulation, because
    temperature and salinity together determine
    density of seawaterThermo temperaturehaline
    salt

8
Where does the Oceans Deepest Water Come From?
  • The densest seawater is cold and salty
  • This is formed at high latitudes in the North and
    South AtlanticNorth Atlantic Deep Water
    (NADW)Antarctic Bottom Water (AABW)

9
Density of Sea Water
NADW


AABW
10
Density Rules!
11
Deep Water Masses
12
Water Massesand oceanmixing
13
Mediterranean Water
14
Mediterranean Water
15
Mediterranean Water
16
Deep Atlantic Circulation
17
Tracers in the Ocean
  • Track the motion (direction and velocity)
  • 14C, cosmic rays in the upper atmos
    (half-life is 5700 years)3H, nuclear weapons
    testing (half-life is 12.5 years)CFCs,
    chlorinated fluoro-carbons

18
The Great Conveyor Belt
19
Closing Isthmus of Panama and onset of the Ice
Ages?
20
Consequences of Global Flow
  • Ocean turnover is about 1500 years (time for a
    round trip on the conveyor belt)
  • Deep water (made in the polar Atlantic) contains
    abundant O2 and CO2
  • The high O2 content promotes oxidation of bottom
    sediments
  • The CO2 content controls CCD (Carbonate
    Compensation Depth)

21
Carbon Cycle and Global Warming
  • The temperature of bottom water formation
    determines how much CO2 is dissolved in deep
    ocean water
  • The rate of overturn of the oceans determines the
    burial rate of C from the atmosphere
  • Organic C accumulates in sediments, depending on
    the O2 content of deep ocean

22
Carbon Cycle and Global Warming
  • Organic C in sediments is reduced to CH4 (methane
    gas)
  • Methane gas migrates upward and can be trapped as
    frozen gas hydrates near the ocean floor

23
Gas Hydrates
24
Gas Hydrates
25
Gas Hydrates
26
Gas Hydrates
27
Climate Change Concerns
  • What happens when sea level falls?(negative
    feed-back)
  • What happens when deep water warms?(positive
    feed-back)
  • Both effects liberate gas hydrates (CH4), which
    combines with O2 to form CO2, ultimately reaching
    the atmosphere

28
Deep Ocean Circulation
  • The ocean has an enormous capacity to absorb and
    release greenhouse gases
  • So, the rate, temperature and composition of
    seawater circulating through the deep ocean is
    vitally important in assessing long term climate
    change
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