Lecture 6: Oceanic Circulation

Vocabulary flashcards covering oceanic basins, layers, chemical properties, currents, thermohaline circulation, tides, and upwelling from Lecture 6: Oceanic Circulation.

World Ocean

The single, interconnected body of salt water that covers $71\%$ of Earth's surface and holds most of its water, divided into five principal basins.

Pacific Ocean

The largest ocean basin on Earth, accounting for $45\%$ of Earth's water surface and covering $155{,}557{,}000\,\text{km}^2$ ($60{,}061{,}000\,\text{mi}^2$).

Atlantic Ocean

The second-largest ocean basin, covering $24\%$ of Earth's water surface and $76{,}762{,}000\,\text{km}^2$ ($29{,}638{,}000\,\text{mi}^2$), which is less than half the size of the Pacific Ocean.

Indian Ocean

The ocean basin covering $20\%$ of Earth's water surface and $68{,}556{,}000\,\text{km}^2$ ($26{,}470{,}000\,\text{mi}^2$), slightly smaller than the Atlantic Ocean.

Arctic Ocean

The smallest and shallowest principal ocean basin, representing $4\%$ of Earth's water surface and $14{,}056{,}000\,\text{km}^2$ ($5{,}427{,}000\,\text{mi}^2$).

Southern Ocean

The ocean basin surrounding Antarctica, representing $6\%$ of Earth's water surface and covering $20{,}327{,}000\,\text{km}^2$ ($7{,}849{,}000\,\text{mi}^2$).

Total Hydrosphere Moisture Inventory

The distribution of Earth's water, consisting of $97.2\%$ salt water (oceans) and $2.8\%$ freshwater (composed of $2.15\%$ glaciers, $0.62\%$ groundwater, $0.009\%$ freshwater lakes, $0.005\%$ soil moisture, $0.001\%$ atmosphere, and $0.0001\%$ streams).

Epipelagic zone

The relatively warm and sunlit surface layer of the ocean extending from the sea surface down to a depth of $200\,\text{m}$ ($650\,\text{ft}$).

Mesopelagic zone

The oceanic layer lying directly below the epipelagic zone, situated above the bathypelagic zone.

Bathypelagic zone

The intermediate deep-ocean vertical layer located between the mesopelagic zone and the abyssopelagic zone.

Abyssopelagic zone

The deep pelagic layer situated below the bathypelagic zone and above the hadal zone, covering the abyssal plains.

Hadal zone

The deepest oceanic zone, occurring exclusively in deep-sea trenches extending below $6{,}000\,\text{m}$ ($19{,}685\,\text{ft}$).

Salinity

The concentration of dissolved minerals and salts in seawater, which averages $35‰$ ($3.5\%$) globally.

Halocline

A vertical oceanic layer where salinity changes dramatically and rapidly with increasing water depth.

Ocean Acidification

The ongoing decrease in ocean pH caused by the absorption of atmospheric $CO_2$ (roughly one-third of anthropogenic emissions since the late 1800s), which reacts with seawater to form carbonic acid.

Elphidium crispum

A single-celled foraminifer with an exoskeleton composed of calcium carbonate ($CaCO_3$), vulnerable to ocean acidification because fewer calcium ions remain available in acidified waters.

Desalination

The costly and energy-intensive industrial process of removing dissolved salts from ocean water to provide potable drinking water.

Surface Ocean Currents

Horizontal ocean water movements driven primarily by global surface wind patterns and the Coriolis effect.

Deep Ocean Currents

Subsurface water flows driven by differences in water density, controlled by temperature and salinity variations.

Gyre

A large, circular loop of ocean currents located in subtropical high-pressure belts ($30^\circ\text{ N}$ and $30^\circ\text{ S}$), driven by winds, the Coriolis effect, and continental boundaries.

Western Boundary Currents

Strong, deep, narrow, and fast-moving ocean currents that transport warm water poleward along the east coasts of continents.

Eastern Boundary Currents

Weak, broad, shallow, and slow-moving ocean currents that carry cold water equatorward along the west coasts of continents.

Upwelling

The process by which offshore surface winds push warm surface water away from a coast, causing deeper, colder, and nutrient-rich water to rise from beneath to replace it.

Thermocline

A vertical transition layer in the ocean characterized by a rapid drop in water temperature with increasing depth.

Tides

Periodic daily rises and falls of ocean surface levels caused by the gravitational pull of the Moon and the Sun, producing tidal bulges on opposite sides of Earth.

Tidal range

The vertical difference in height between consecutive high tide and low tide.

Spring tides

Tides with the highest tidal range, occurring when the Sun, Earth, and Moon align in a straight line.

Neap tides

Tides with the lowest tidal range, occurring when the gravitational pull of the Sun and Moon act at right angles to each other relative to Earth.

Perigean spring tides

Tides that produce the highest tidal ranges because spring tides coincide with the Moon being at perigee (closest point to Earth).

Thermohaline circulation

Deep-ocean density-driven circulation caused by differences in temperature and salinity, where cold, salty water sinks at high latitudes.

Global conveyor belt

The interconnected system of surface currents and deep thermohaline circulation that plays a crucial role in long-term global climate and heat energy transfer.

Waves

Disturbances along the ocean surface that transfer energy through circular orbital motions of water particles, breaking to move actual water at shorelines.

Antarctic Circumpolar Current

Also known as the West Wind Drift, a massive cold surface current flowing eastward completely around Antarctica without deflection by landmasses.

Beaufort Gyre

A major wind-driven clockwise ocean circulation system in the Arctic Ocean that acts as a reservoir of fresh water and sea ice.