stretch_deformation

stretch_deformation(fx, fy)

New in Metview version 5.13.0.

Computes the stretch deformation of 2-dimensional vector fields.

Parameters

  • fx (Fieldset) – zonal (west-east) vector component fieldset

  • fy (Fieldset) – meridional (south-north) vector component fieldset

Return type

Fieldset

The computations for a vector field f=(fx,fy) are based on the following formula:

\[d(f) = \frac{1}{R \ cos\phi}\frac{\partial f_x}{\partial \lambda} - \frac{1}{R}\frac{\partial f_y}{\partial \phi} - \frac{f_y}{R}tan\phi\]

where:

  • R is the radius of the Earth (in m)

  • \(\phi\) is the latitude

  • \(\lambda\) is the longitude.

The derivatives are computed with a second order finite-difference approximation. The resulting fields contain missing values on the poles.

Warning

stretch_deformation() is only implemented for regular latitude-longitude grids.

Note

See also shear_deformation(), divergence() and vorticity().