Intro Ocean - 4 Motion

In what parts is the ocean circulation commonly divided?

Wind-driven circulation and thermohaline (buoyancy-driven) circulation.

What is ventilation in oceanography?

The process by which surface waters exchange gases and properties with the atmosphere and enter the ocean interior.

What is subduction in oceanography?

The sinking and transport of surface water into the ocean interior, often along isopycnals.

What is isopycnal flow?

Flow along surfaces of constant density, with little movement across density surfaces.

What is isopycnal mixing?

Mixing along surfaces of constant density, primarily caused by turbulence and stirring.

What is diapycnal mixing?

Mixing across surfaces of constant density, requiring energy to overcome stratification.

What causes diapycnal mixing in the ocean?

Turbulence generated by tides, winds, internal waves, and convection.

What is upwelling?

The upward transport of deeper water toward the surface, often driven by wind-induced divergence or buoyancy processes.

What is downwelling?

The downward transport of surface water into deeper layers, often driven by convergence or densification.

Which combination of water properties helps identify a water mass?

Its characteristic temperature and salinity (T–S properties).

What percentage of incoming solar radiation is reflected back to space?

Approximately 30% (the planetary albedo).

What percentage of incoming solar radiation is absorbed by Earth's surface?

Approximately 47%; the remaining ~23% is absorbed by the atmosphere and clouds.

Why is outgoing longwave radiation important for Earth's energy balance?

Earth emits absorbed solar energy as longwave radiation; greenhouse gases absorb and re-emit some of it, warming the surface and atmosphere.

Where is net radiation generally positive and negative?

Positive at low latitudes, where energy is gained; negative at high latitudes, where energy is lost.

What are the three global atmospheric circulation cells, their locations, and drivers?

Hadley (0–30°): thermally driven convection; Ferrel (30–60°): indirectly driven by eddies; Polar (60–90°): cold-air subsidence and convection.

Where do the major jet streams occur, and what drives them?

Near circulation cell boundaries, driven mainly by strong horizontal temperature and pressure gradients and modified by Earth's rotation.

How are atmospheric wind patterns reflected in the ocean?

Winds exert surface stress on the ocean, driving currents and transferring momentum.

How does the Coriolis force affect moving water?

It deflects motion to the right in the Northern Hemisphere and left in the Southern Hemisphere; it changes direction, not speed.

What is an Ekman current?

The wind-driven current resulting from the balance of wind stress, Coriolis force, and friction.

What is the Ekman spiral?

The rotation and weakening of current velocity with depth due to friction and the Coriolis effect, producing a spiral pattern.

What is the Ekman layer depth?

The depth over which wind-driven currents are strongly influenced by friction; often tens of metres, but can reach ~100–200 m depending on conditions.