Coriolis effect is the single most important effect in physical oceanography. Coriolis force is a fictitious force that exists in all rotating reference systems. Newton's second law in a rotational reference system is:


Due to the slow rotation of Earth (T=24 h, ω=7,27x10-5 rad/s), the Coriolis force is very small. The effect of Coriolis is noticeable in large-scale and long-duration phenomena such as large-scale flow of wind and ocean currents. Such motions are constrained by the surface of the earth, so only the horizontal component of the Coriolis force is important.

Coriolis Effect is the phenomenon where current and wind are deflected as they travel across or above the earth's surface.

North hemisphere: Deflection to the right → spin counterclockwise

South hemisphere: Deflected to the left → spin clockwise

A more intuitive explanation of the Coriolis effect: An object that is decoupled form the solid earth (such as ocean water and air) move in deflected track due to the fact that the Earth's speed of rotation is slower at the poles that at the equator. Coriolis effect affects air and water masses and governs atmospheric and ocean-surface circulation patterns.



Simplified/intuitive explanation:

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- Coriolis force perpendicular to the velocity vector.
- The small scale, such as a sink at your house, other factors, such as theshape of the sink and the direction of initial velocity of the water are theimportant factors for the direction of spinning. Coriolis effect is way down tothe list of phenomena that affect that flow.

f-plane is a Cartesian coordinate system on which the Coriolis force is assumed constant.

β-plane the Coriolis force is assumed to vary linearly with the latitute.

Futher Reading

IRI DataLibrary Plythora of dataset from NOAA, NASA and many other sources

AmericanMeteorological society


2. Inertial Oscillations

Inertial Oscillations (inertial wave): Is the motion ofocean water where only the Coriolis force acts on the water. Such a motion canbe initiated when:

1. Wind blows across the sea for a short time

2. Water exits from the mouth of an estuary

After the initiation of the motion, only the coriolos force acts on thewater (no compensating hydrostatic pressure gradient as in geostrophic flow)and the water body is not in equilibrium.

In general. inertial oscillations are possible only when a fluid is rotatingand the oscillation is in the bulk of the fluid, not at its surface. From theequations, it can be seen that the oscillation period is determined be thelatitude.

T=2πf where f=2Ωsin⁡φ

Latidute [deg] Period [hours]
φ = 0 T = infinite
φ = 10 T =69 h
φ = 35 T =21 h
φ = 45 T =17 h
φ = 60 T = 14 h
φ = 90 T = 12 h