PHYSICAL OCEANOGRAPHY Part 3: Heat Budget

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PHYSICAL OCEANOGRAPHYPart 3 Heat Budget
Ocean Currents

• GEOL 1033
• (Lessons 27-28, 33, 34)
• Ppt file 103 - 24

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EARTH'S HEAT BUDGET

• About half of solar radiation, mostly as visible
  light, reaches Earth's surface
• Re-radiated energy is in the form of infrared
  radiation
• Carbon dioxide and water vapour temporarily
  absorb some of this infrared (greenhouse effect
  global warming)

half
Infrared radiation heat
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LATITUDINAL VARIATIONS IN SOLAR RADIATION

• High latitudes receive less solar energy per unit
  of surface area

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LATITUDINAL VARIATION IN HEAT GAINS AND LOSSES

• Heat gains are greatest at lower latitudes
• Heat losses are relatively greater at higher
  latitudes
• Heat is redistributed by air ocean currents

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Global Air Circulation Cells
Wet
Dry
Wet
Dry
Wet
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Major Surface Wind Patterns

• Simplify this model look at surface winds
• Winds are mainly responsible for surface ocean
  currents

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Coriolis Effect in Northern Hemisphere

• Shifts winds ocean currents to the right
• Related to faster surface rotation rates near the
  equator in comparison to those at higher latitudes

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Influences on Oceanic Gyre Formation

• Winds cause currents
• Currents redistribute heat from Sun
• Coriolis effect shifts current directions to
  right in N. Hemi. left in So. Hemi.
• Continents block pure E-W flow, creating boundary
  currents
• Some gravitational influence

Northern Subtropical gyre
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North Atlantic Gyre System

• Know these currents
• Western boundary currents (e. g., Gulf Stream)
  are deeper, narrower, and faster than eastern
  boundary currents (e. g., Canary Current)
• Review Lessons 33 34

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Major Ocean Surface Currents Climatic Zones

• Review Exercise 15 (Completed answer sheet on
  page 235 is due next Thursday, Dec. 2nd.)

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Circum-Antarctic Surface Circulation

• Less interference from north-south oriented
  continental masses

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REMEMBER THE PYCNOCLINE

• Halocline refers to the salinity increase
  coinciding with the thermocline
• Pycnocline is the density change associated with
  the thermocline and halocline

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REMEMBER LATITUDINAL VARIATIONS IN AVERAGE DEPTH
OF VERTICAL DENSITY ZONES

• Surface zone
• Pycnocline
• Deep zone

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PACIFIC OCEAN Salinity/Temperature Structure
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ATLANTIC OCEAN Salinity/Temperature Structure
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Circulation of Atlantic Ocean Water Layers

• Note Antarctic Intermediate and Bottom Waters
• Find the North Atlantic Deep Waters
• 
  AC ? AD ?

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Antarctic Ocean Upwelling and Downwelling
North Atlantic Deep Waters
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• Stopped Here

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Ekman Spiral

• Due to Coriolis effect, can get a weak
  countercurrent at depth

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Northern Hemisphere Coastal Upwelling and
Downwelling

• Coriolis right shift of surface waters (Ekman
  spiral effect)
• Onshore to produce downwelling
• Offshore to produce upwelling

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Southern Hemisphere Coastal Upwelling and
Downwelling

• Coriolis left shift of surface waters (Ekman
  spiral effect)
• Onshore to produce downwelling
• Offshore to produce upwelling
• El Nino off NW coast of So. Am.

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Circulation of Atlantic Ocean Water Layers

• Note Antarctic Intermediate and Bottom Waters
• Find the North Atlantic Deep Waters
• Note Med. Salty, warm water AC
  ? AD ?

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The Oceanic Conveyor Belt

• Thermohaline surface to deep planetary
  circulation system.
• A disruption may bring on another Ice Age!

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