Week One- Dynamic Theory of Tides

If the equilibrium theory was correct what three things would be true

1. High tide would occur at same time along each line of longitude

   • Tides of high tide do not occur at same time along each line of longitude

2. Tidal range would be largest at equator and smallest at poles

   • Tidal range is not largest at equator nor smallest at poles

3. You would get semi-diurnal tides at the equator and diurnal tides nearer to poles

Are any of the principles of equilibrium tide theory valid

No

What are the four things that contribute to the dynamic theory that result in the observed tide being different from the equilibrium theory tide

1. Amphidromic systems

2. Standing waves- resonance

3. Shallow water effects

4. Topography

What is an amphidromic system

The combined constraint of ocean basin geometry and the influence of Coriolis

How does friction play a role in dyanmic theory tides

• Outgoing tidal wave has less energy than incoming wave

• Amphidromic point is shifted to the left

• Tidal range on right of gulf is greater than on the left

• In strongly dissipative systems the amphidromic point can be shifted onto land

What is resonance

Resonance occurs when a system is able to oscillate with greater amplitude at a specific frequency. It happens when the frequency of an external force matches the system's natural frequency, resulting in a significant increase in energy transfer.

How are standing waves and resonance linked to dynamic theory

• Systems that are forced by ocscillations close to their natural periods have large amplitude responses i.e. larger tides

  In standing waves

• Nodes- Amplitudes are zero

• Antinodes- Amplitude is max

How does shallow water relate to dynamic theory

Tidal wave slows done significantly as it crosses into shallower water due to friction between wave and seabed.

Wavelength decreases and energy has to stay same so wave height increases- tides are larger on continental shelves compared to open ocean