Understanding El Niño and La Niña

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Questions and Answers

Match the following oceanic phenomena with their descriptions:

acoustical tomography = A technique for studying ocean structure using low-frequency sound Antarctic Bottom Water = The densest ocean water formed in Antarctica Antarctic Circumpolar Current = The largest ocean current that flows permanently eastward caballing = Mixing water masses of identical densities resulting in denser mixture

Match the following oceanic processes with their effects:

coastal upwelling = Upwelling induced by wind near a coast contour current = Dense bottom current flowing around seabed projections convergence zone = Boundary where waters of different densities meet countercurrent = Surface current flowing opposite to an adjacent current

Match the following terms related to water circulation with their definitions:

current = Mass flow of water, typically horizontal downwelling = Vertical movement of surface water downward eastern boundary current = Weak, cold current at the eastern boundary of an ocean Eddy = Circular movement of water near current obstructions

Match the following models of oceanic dynamics with their characteristics:

Ekman spiral = Model showing wind's effect on water layers Ekman transport = Net water transport at an angle due to the Ekman spiral Antarctic Circumpolar Current = Driven by powerful westerly winds coastal upwelling = Brings nutrient-rich water to the coast Signup and view all the answers

Match the following terms with their associated effects on marine ecosystems:

downwelling = Decreases nutrient availability in certain areas coastal upwelling = Enhances productivity by bringing nutrients to the surface Ekman transport = Influences the distribution of marine organisms caballing = Creates denser water that can impact currents Signup and view all the answers

Match the following currents with their main characteristics:

Antarctic Bottom Water = Formed during Southern Hemisphere winters eastern boundary current = Examples include the Canary and Humboldt Currents countercurrent = Flows opposite to adjacent surface currents contour current = Flows around seabed features, typically denser water Signup and view all the answers

Match the following oceanographic terms with their explanations:

Ekman spiral = Water drifts at an angle to the wind due to Coriolis effect Eddy = Formed by interactions between two opposing currents convergence zone = Forms boundaries of various oceanic areas caballing = Increases density of mixed water masses Signup and view all the answers

Match the following processes with their influences on climate patterns:

coastal upwelling = Affects local temperatures and fisheries downwelling = Can lead to reduced surface temperatures Antarctic Circumpolar Current = Influences global ocean mixing and climate Ekman transport = Impacts water temperatures across regions Signup and view all the answers

Match the following terms with their definitions:

El Niño = A warm water current off the coast of western South America La Niña = An event characterized by cooler surface temperatures in the eastern South Pacific Southern Oscillation = A reversal of airflow between low and high pressure over the Pacific ENSO = A phenomenon combining El Niño and the Southern Oscillation Signup and view all the answers

Match the following oceanic processes with their descriptions:

Geostrophic gyre = Circular current in balance between Coriolis effect and pressure Langmuir circulation = Shallow, wind-driven circulation in horizontal spiral bands Thermohaline circulation = Water movement caused by temperature and salinity differences Equatorial upwelling = Nutrient-rich deep water replacing surface water near the equator Signup and view all the answers

Match the following currents with their characteristics:

Gulf Stream = Strong western boundary current of the North Atlantic North Equatorial Current = A transverse current linking eastern and western boundaries North Atlantic Deep Water = Cold, dense water formed in the Arctic ocean Surface Current = Horizontal flow of water at the ocean surface Signup and view all the answers

Match the following descriptions with the correct terms:

El Niño = Caused by a breakdown of trade-wind circulation La Niña = Typically occurs at the end of an El Niño event Sverdrup (sv) = A unit of volume transport in oceanography Gyre = Circuit of mid-latitude currents around an ocean basin Signup and view all the answers

Match the following currents to their direction of flow:

Transverse current = Flows east-to-west or west-to-east Undercurrent = Flows beneath a surface current in the opposite direction Equatorial upwelling = Westward flow that is deflected poleward Gulf Stream = Flows along the Atlantic coast of the United States Signup and view all the answers

Match these phenomena with their effects:

El Niño = Increases surface temperature in the eastern Pacific La Niña = Strengthens normal tropical circulation Global ocean conveyor belt = Transports heat across the globe Southern Oscillation = Drives changes in atmospheric pressure over the Pacific Signup and view all the answers

Match the following events with their timing or occurrence:

El Niño = Typically occurs every few years La Niña = Follow El Niño events ENSO = Represents coupled ocean-atmospheric phenomena Geostrophic gyre = Found around the periphery of ocean basins Signup and view all the answers

Match the following types of circulation with their descriptions:

Langmuir circulation = Characterized by wind-driven, spiral bands Thermohaline circulation = Involves density-driven flow in oceans Equatorial upwelling = Brings nutrient-rich water to the surface Surface current = Generally flows in the upper layer of the ocean Signup and view all the answers

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Study Notes

El Niño and La Niña

El Niño is a warm current that occurs off the coast of western South America, caused by a break down in trade wind circulation.
La Niña is an occurrence in which the tropical Pacific atmospheric and oceanic circulation strengthens and the water temperature in the eastern South Pacific drops below average.
El Niño and La Niña are part of a complex system called ENSO (El Niño-Southern Oscillation).

Ocean Currents

Ocean currents are responsible for the transfer of heat, salt, and nutrients throughout the globe
Surface Currents: The horizontal flow of water at the ocean's surface.
Undercurrent: A current that flows beneath a surface current, usually in the opposite direction.
Transverse Current: East-to-west or west-to-east current that links eastern and western boundary currents.
Eastern Boundary Current: A weak, cold, diffuse, slow-moving current at the eastern boundary of an ocean.
Western Boundary Current: A strong, warm, narrow, fast-moving current at the western boundary of an ocean.
Gyre: A circular current of mid-latitude currents around the periphery of an ocean basin.
Geostrophic Gyre: A circular current in balance of the Coriolis effect and the pressure gradient.
Global Ocean Conveyor Belt: A simplified outline of the 3D global circuit that ocean currents follow as they transport heat around the globe.
Antarctic Circumpolar Current (West Wind Drift): The largest ocean current, driven by powerful westerly winds north of Antarctica.

Other important ocean terms

Upwelling: The movement of deep, cold, nutrient-rich water to the surface.
Equatorial Upwelling: Occurs on either side of the equator as water moves westward and is deflected slightly poleward, replaced by deep water.
Coastal Upwelling: Occurs adjacent to a coast, usually induced by wind.
Downwelling: The movement of surface water vertically downward.
Langmuir Circulation: Shallow, wind-driven circulation of water in horizontal, spiral bands.
Ekman Spiral: A theoretical model of the effect of wind blowing over the ocean. The surface layer drifts at an angle to the wind due to the Coriolis effect.
Ekman Transport: The net water transport, the sum of layer movement due to the Ekman spiral.
Convergence Zone: The line along which waters of different density converge.
Countercurrent: A surface current flowing in the opposite direction from an adjacent surface current.
Eddy: A circular movement of water usually formed when currents pass obstructions or between two adjacent currents flowing in opposite directions.

Properties of Water

Temperature-Salinity (T-S) Diagram: A graph showing the relationship between temperature and salinity with depth.
Thermohaline Circulation: Water circulation produced by differences in temperature and/or salinity.

Ocean Processes

Caballing: Mixing of two water masses of identical densities, but different temperatures and salinities, resulting in a denser mixture.
Contour Current: A bottom current flowing around (rather than over) seabed projections.

Notable Water Masses

North Atlantic Deep Water: Cold, dense water formed in the Arctic that flows onto the floor of the North Atlantic.
Antarctic Bottom Water: The densest ocean water, formed primarily in Antarctica's Weddell Sea.

Oceanographic Techniques

Acoustical Tomography: A technique for studying ocean structure that uses low-frequency sound pulses to sense differences in water temperature, salinity, and movement.