WVAntialiasing

Antialiasing filter

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Declaration

WVAntialiasing < WVForcing

Overview

This forcing removes (sets to zero) energy in the largest 1/3 modes to prevent quadratic aliasing. This is the correct de-aliasing for the horizontal fourier modes, but is not exactly correct for the vertical modes in variable stratification. You can thus manually set Nj, otherwise it will default to options.Nj = floor(2*wvt.Nj/3);.

Very important You should almost never use this forcing, as de-aliasing is built-in at the transform level and enabled by default. For performance reasons is far more optimal to simply never compute the de-aliased modes. The purpose of this forcing to allow direct measurement of the effect of the de-aliasing on energy and potential enstrophy. It is quite slow and thus we recommend it be used for diagnostic purposes only.

Usage

This is likely to change in the future, but at the moment several of the transforms have a function that will make a new transform in the identical state, but with the antialiasing filter explicitly added.

wvtAA = wvt.waveVortexTransformWithExplicitAntialiasing();

Topics

• Properties
  • M spectral matrix that multiplies Ap,Am,A0 to zero out the aliased modes
  • effectiveHorizontalGridResolution returns the effective grid resolution in meters
  • effectiveJMax returns the effective highest vertical mode
• CAAnnotatedClass requirement
  • classRequiredPropertyNames Returns the required property names for the class
• Other
  • WVAntialiasing initialize the WVAntialiasing

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