Oceanographic Principles

Oceanographic Principles

• Chronometer: Used for precise timekeeping, crucial for determining longitude.
• Ocean Origins: Volcanic emissions released water vapor, which condensed and precipitated, forming Earth's oceans.
• Oldest Fossils: 3.5 billion-year-old photosynthetic bacteria are the oldest known fossils.
• Alfred Wegener: Proposed the theory of Continental Drift.
• Harry Hess: Developed the theory of Seafloor Spreading.
• Plate Boundaries:
  • Divergent Boundaries: Create mid-ocean ridges (MORs) and rift valleys.
  • Convergent Boundaries: Form trenches and volcanic arcs (mountain ranges or islands).
    • Ocean-Ocean Convergence: Leads to island arcs, with one oceanic plate subducting beneath another.
    • Ocean-Continent Convergence: Creates mountains and volcanic arcs, with oceanic lithosphere subducting beneath a continental plate.
    • Continent-Continent Convergence: Results in massive mountain ranges; plates are too buoyant to subduct, leading to crustal thickening and crumpling.
  • Transform Boundaries: Generate fault lines.

Ocean Features and Processes

• Guyots: Flat-topped seamounts.
• Satellite Altimetry: Techniques (like Geosat, CryoSat-2, and Jason-1) used to measure ocean surface height.
• Hydrothermal Vents: Located along mid-ocean ridges (MORs).
• Ocean Salinity Variations:
  • High Latitudes: Lower salinity due to melting icebergs and precipitation.
  • Low Latitudes: Higher salinity due to high evaporation rates.
  • Equator: Moderate salinity due to precipitation and evaporation balance.
• Factors Affecting Salinity:
  • Decreasing Salinity: Precipitation, runoff, and melting ice.
  • Increasing Salinity: Sea ice formation and evaporation.
• Ocean Density: Salinity and temperature influence density; lower temperature means higher density, higher salinity means higher density.
• pH Regulation: Ocean pH is maintained by the Carbonate Buffering System.
• Desalination: Has potential negative impacts on marine life and requires significant energy.
• Average Ocean Depths:
  • Overall: ~3-4 km
  • Mid-Ocean Ridges (MORs): ~2.5 km
  • Continental Shelf: ~100-200 m
• Average Ocean Age: ~200 million years.

Oceanographic Equations and Concepts

• Median Residence Time Calculation: Total volume divided by median inflow or outflow rate.
• Temperature Conversions:
  • Celsius to Fahrenheit: ºC = (ºF - 32) / (9/5)
  • Fahrenheit to Celsius: ºF = (ºC x 9/5) + 32

Wilson Cycle

• A cycle of ocean basin formation, growth, and closure.
• Stages:
  • Embryonic: Continental crust fractures, creating a rift valley.
  • Juvenile: New ocean forms via seafloor spreading.
  • Mature: Large ocean basins develop (e.g., Atlantic).
  • Declining: Oceanic lithosphere subducts.
  • Terminal: Oceanic basin closes, and continents collide.
  • Suturing/Extinction: Ocean basin closes completely.

Ocean Salt Balance

• Salt Inputs:
  • Continental weathering and river discharge.
  • Volcanic discharge.
  • Hydrothermal vents.
  • Decaying organisms.
• Salt Outputs:
  • Sea spray.
  • Uptake by organisms.
  • Circulation through MOR systems.
  • Sediment incorporation.
  • Subduction.