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CLIMATE/EARTH 401�Geophysical Fluid Dynamics�Dynamical Meteorology

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Vorticity 3: Derivation of Equation

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How to compute the time rate of change of vorticity.

  • If the change in vorticity is important, then we need a way to compute it
  • We have the tools to do this.

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How do you solve this set of equations?

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The answer

  • Multiply each of the equations by something.

(More generally, do something to the equation, but it is smart to think about what to do.)

​

  • Add them together.

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Full equations of motion, height coordinates

How would you calculate of the time rate change of the vertical component of vorticity?

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The scaled horizontal momentum equation in z coordinates

no viscosity

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Relative Velocity and Vorticity

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Take derivatives

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Take derivatives

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Take derivatives

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Take derivatives

Pay attention to details of calculus here

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Subtract these equations: Conservation of vorticity

(A rather long derivation—and a great homework problem…)

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Equations of motion�(p, pressure, as a vertical coordinate)

tangential coordinate system on Earth’s surface

(x, y, p) = (+ east, + north, pressure is vertical coordinate)

k・∇×

(

)

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End: Vorticity 3: Derivation of Equation