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/ = / (+), which indicates that these long equatorial Rossby waves move in the opposite direction (westward) of Kelvin waves (which move eastward) with speeds reduced by factors of 3, 5, 7, etc. To illustrate, suppose c = 2.8 m/s for the first baroclinic mode in the Pacific; then the Rossby wave speed would correspond to ~0.9 m/s, requiring a 6 ...
Equatorial waves are oceanic and atmospheric waves trapped close to the equator, meaning that they decay rapidly away from the equator, but can propagate in the longitudinal and vertical directions. [1] Wave trapping is the result of the Earth's rotation and its spherical shape which combine to cause the magnitude of the Coriolis force to ...
For a barotropic ocean, the Rossby radius is () /, where is the gravitational acceleration, is the water depth, and is the Coriolis parameter. [ 2 ] For f = 1×10 −4 s −1 appropriate to 45° latitude, g = 9.81 m/s 2 and D = 4 km, L R ≈ 2000 km; using the same latitude and gravity but changing D to 40 m; L R ≈ 200 km.
The eastward speed of propagation of these waves can be derived for an inviscid slowly moving layer of fluid of uniform depth H. [2] Because the Coriolis parameter (f = 2Ω sin(θ) where Ω is the angular velocity of the earth, 7.2921 × 10 −5 rad/s, and θ is latitude) vanishes at 0 degrees latitude (equator), the “equatorial beta plane” approximation must be made.
The Rossby number is a dimensionless number which characterises the strength of inertia compared to the strength of the Coriolis force. The quasi-geostrophic equations are approximations to the shallow water equations in the limit of small Rossby number, so that inertial forces are an order of magnitude smaller than the Coriolis and pressure ...
Topographic Rossby waves are one of two types of geophysical waves named after the meteorologist Carl-Gustaf Rossby. The other type of Rossby waves are called planetary Rossby waves and have a different physical origin. Planetary Rossby waves form due to the changing Coriolis parameter over the earth. Rossby waves are quasi-geostrophic ...
One can identify a terrestrial Rossby wave as its phase velocity, marked by its wave crest, always has a westward component. [1] [4] However, the collected set of Rossby waves may appear to move in either direction with what is known as its group velocity. In general, shorter waves have an eastward group velocity and long waves a westward group ...
Most high-and low-pressure areas seen on weather maps (such as surface weather analyses) are synoptic-scale systems, driven by the location of Rossby waves in their respective hemisphere. Low-pressure areas and their related frontal zones occur on the leading edge of a trough within the Rossby wave pattern, while high-pressure areas form on the ...