What causes a Kelvin wave?

What causes a Kelvin wave?

Internal coastal Kelvin waves can be generated by wind-induced, time-dependent coastal upwelling. Coastal upwelling (downwelling) is caused by an Ekman mass flux transported offshore (onshore) and forced by longshore winds. The disturbances can then propagate along the coast as boundary-trapped internal Kelvin waves.

What is the direction of the Kelvin wave?

The Kelvin wave moves equatorward along a western boundary, poleward along an eastern boundary, and cyclonically around a closed boundary (counterclock- wise in the Northern Hemisphere and clockwise in the Southern Hemisphere).

What boundary is trapped Kelvin waves?

The Kelvin wave is a coastally trapped wave; it needs a coastline. In the NH, the wave propagates poleward along an eastern boundary and equatorward along a western boundary with its maximum amplitude at the boundary.

What are the characteristics of Kelvin waves?

A range of Kelvin waves have been observed. All are traveling waves that move eastward with time. They have wave perturbations in temperature and zonal and vertical winds; the meridional winds associated with the wave are zero. Kelvin waves are normally observed to have low zonal wavenumbers (1–3).

What is a Kelvin wave and how is it related to El Niño?

When they form at the equator, Kelvin waves bring warm water, which is associated with higher sea levels, from the western Pacific to the eastern Pacific. A series of Kelvin waves starting in spring is a well-known precursor to an El Niño, a periodic climate phenomenon that can affect weather patterns around the world.

What is the propagation speed of Kelvin waves?

Coastal Kelvin waves propagate around the northern hemisphere oceans in a counterclockwise direction using the coastline as a wave guide. These waves, especially the surface waves are very fast moving, typically with speeds of ~2.8 m/s, or about 250 kilometers in a day.

Do Rossby waves move to the west or east?

Unlike waves that break along the shore, Rossby waves are huge, undulating movements of the ocean that stretch horizontally across the planet for hundreds of kilometers in a westward direction.

What direction do waves move in?

Waves are created by the wind and then radiate in all directions away from the disturbance. Currents represent the movement of water particles which is controlled by winds and density differences. Waves and currents can travel in opposite directions.

Which direction is the wave energy moving?

The direction of wind is the primary predictor of wave direction in the ocean. If the wind is blowing from the north to the south, then the wave energy will travel in the southward direction. Similarly, if the wind blows in the eastward direction, then the wave energy will travel towards the east.

What are Kelvin waves in the ocean?

Unlike the waves you see at the beach, Kelvin waves do not curl over and then crash. They are more like the waves in your bathtub, which slowly slosh around. They don’t break, but they still have broad peaks and valleys that change the depth of the water (the ocean equivalent is “sea surface height”).

What is the speed of the equatorial Kelvin wave?

For the first baroclinic mode in the ocean, a typical phase speed would be about 2.8 m/s, causing an equatorial Kelvin wave to take 2 months to cross the Pacific Ocean between New Guinea and South America; for higher ocean and atmospheric modes, the phase speeds are comparable to fluid flow speeds.

What happens to waves at a boundary?

When a wave reaches a boundary, a point where the medium changes, three things occur. Some of the wave is transmitted on into the new medium, some of the wave is reflected back into the original medium, and some of the wave energy is absorbed.

What are the four 4 characteristics of waves?

No matter whether you are talking about vibrations or waves, all of them can be characterized by the following four characteristics: amplitude, wavelength, frequency, and speed. The amplitude of a wave can be described as the maximum distance the molecules are displaced from their starting place .

What are the 5 common characteristics of waves?

• Property 1:Amplitude. The maximum displacement of the wave from the mean position is called the amplitude of the wave. …
• Property 2: Frequency. …
• Property 3: Wavelength. …
• Property 4: Time Period. …
• Property 5: Speed.

What are the three important characteristics of wave motion?

The main characteristics of wave motion are described below: In wave motion, the particles of the medium vibrate about their mean positions. The particles of the medium do not move from one place to another. A wave motion travels at the same speed in all directions in a medium.

What is the boundary condition of waves?

In general, there are two major types of boundary conditions: fixed-endpoint or Dirichlet boundary conditions, and free-endpoint or Neumann boundary conditions, corresponding to holding the end of a string or allowing it to freely oscillate, respectively.

What are the boundary conditions for a reflected wave?

Waves reflect from a boundary in two basic ways depending on whether the boundary is hard or soft. In the case of waves on a string a hard boundary is where the string is firmly attached and a soft boundary is when the end of the string can slide up and down.

What are boundary waves?

The behavior of a wave (or pulse) upon reaching the end of a medium is referred to as boundary behavior. When one medium ends, another medium begins; the interface of the two media is referred to as the boundary and the behavior of a wave at that boundary is described as its boundary behavior.