absolute_momentum#
- metpy.calc.absolute_momentum(u, v, index='index')#
Calculate cross-sectional absolute momentum (also called pseudoangular momentum).
The cross-sectional absolute momentum is calculated given u- and v-components of the wind along a 2 dimensional vertical cross-section. The coordinates of u and v must match.
- Parameters
u (
xarray.DataArray) – The input DataArray of the x-component (in terms of data projection) of the wind.v (
xarray.DataArray) – The input DataArray of the y-component (in terms of data projection) of the wind.index (str or int, optional) – Denotes the index coordinate of the cross-section, defaults to ‘index’ as set by
metpy.interpolate.cross_section
- Returns
absolute_momentum (
xarray.DataArray) – Absolute momentum
Notes
As given in [Schultz1999], absolute momentum (also called pseudoangular momentum) is given by:
\[M = v + fx\]where \(v\) is the along-front component of the wind and \(x\) is the cross-front distance. Applied to a cross-section taken perpendicular to the front, \(v\) becomes the normal component of the wind and \(x\) the tangential distance.
If using this calculation in assessing symmetric instability, geostrophic wind should be used so that geostrophic absolute momentum \(\left(M_g\right)\) is obtained, as described in [Schultz1999].
Changed in version 1.0: Renamed
u_wind,v_windparameters tou,v