Oceanography: Exploring Earth's Vast Marine Realm

Oceanography: Earth's Marine Realm

Ocean Coverage and Resources

Oceans cover 71% of Earth's surface and hold 97% of its water. They provide crucial resources, including one-third of natural gas and oil, 16% of protein, and 50% of our oxygen.

Maps and Projections

A map is a representation, usually on a flat surface, of a region of Earth or the heavens. A projection is the image of a geometric figure reproduced on a line, plane, or surface.

Types of Maps:

• Political
• Physiographic
• Geologic
• Topographic
• Bathymetric

Ocean Provinces

• Continental Margins: Shallow areas close to shore.
• Deep-Ocean Basins: Deep-water areas farther from land.
• Mid-Ocean Ridge: A submarine mountain range.

Geological Features

Hot spots are plumes originating from the core-mantle boundary. The Ring of Fire surrounds the Pacific Plate with convergent boundaries, active volcanoes, and earthquakes.

Oceanic Island Formation

• Hotspots form island chains as the overlying plate moves.
• Island arcs form at ocean-ocean convergent boundaries.

Earth's Layers

Lithosphere: Crust and uppermost mantle. Broken into 14 plates. Rigid. 1-100km.

Asthenosphere: Lower portion of the upper mantle, down to 670km. Soft and deformable.

Evidence for Continental Drift

• Jigsaw puzzle fit of the continents
• Fossil record
• Rock types and structural similarities
• Paleoclimate data

Ocean Sediments

Qualitative models highlight important connections in real-world systems and processes, serving as a first step in developing more complex models.

Sediments are particles of organic and inorganic origin that settle through the water column onto the seafloor (mud).

Foraminifera serve as indicator organisms for climatic change.

Sediment Traps

• Twilight zone explorer
• Moored trap (full ocean depths)
• Surface tethered trap

Ocean Composition and Processes

Milankovitch cycles are periodic processes that alter the amount of solar energy reaching Earth's surface.

Lithogenous sediments: SiO2/CaCO3/weathered fragments of preexisting rock, transported by rivers, glaciers, or wind.

Biogenous sediments: Composed of hard remains of once-living organisms.

Hydrogenous sediments: Formed when dissolved materials precipitate out of solution.

Cosmogenous sediments: Derived from outer space.

Diatoms are microscopic algae with silica shells (frustules).

Foraminifera (calcite) and Radiolaria (silica) are heterotrophic protists.

Pteropods are planktonic snails.

Ocean Buffer System: H2CO3, NaCl, CO2. Ocean pH: 8.1. Photosynthesis increases pH [CO2 + H2O -> Organic carbon + O2], while respiration decreases pH [Organic carbon + O2 -> CO2 + H2O].

Halocline: Layer of rapidly changing salinity.

Isopycnals: Layers of constant density.

Ocean's Influence on Weather and Climate

Weather: Conditions of the atmosphere at a particular time and place.

Climate: Long-term average of weather.

The ocean significantly influences Earth's weather and climate patterns.

El Niño

Warm water moves east, preventing upwelling.

Impacts:

• Peruvian/Ecuadorian anchovy fishery decline
• Higher rainfall in Ecuador, northern Peru, and southern coastal US states
• Disease outbreaks
• Coral bleaching in Australia, the Florida Keys, and Galapagos

La Niña Impacts

• Increased tropical cyclones and storm activity
• Rainfall and flooding in the Caribbean
• Colder winters
• Drier, sunnier, and warmer conditions in the US

Ocean Pressure

The ocean and atmosphere exert pressure on objects within them, called hydrostatic pressure (P).

Hydrostatic Equation: P = ρ x g x h (kg/(m s^2)). 10m depth = 1 bar = 1 atm = 105 N/m^2.

Ocean Currents

Surface Currents: Affect surface water within and above the permanent pycnocline, driven by major wind belts.

Deep Currents: Affect deep water below the pycnocline (90% of ocean water), driven mainly by density differences but influenced by surface winds. Larger and slower than surface currents.

Upwelling: Movement of deeper, cooler waters away from the shore, rising to the surface.

Downwelling: Movement of surface waters toward the shore, accumulating and sinking to the bottom.