potential_vorticity_baroclinic

metpy.calc.potential_vorticity_baroclinic(potential_temperature, pressure, u, v, dx, dy, lats, axis=0, dim_order='yx')

Calculate the baroclinic potential vorticity.

\[PV = -g \frac{\partial \theta}{\partial z}(\zeta + f)\]

This formula is based on equation 7.31a [Hobbs2006].

Parameters:

• potential_temperature ((M, N, P) ndarray) – potential temperature
• pressure ((M, N, P) ndarray) – vertical pressures
• u ((M, N) ndarray) – x component of the wind
• v ((M, N) ndarray) – y component of the wind
• dx (float or ndarray) – The grid spacing(s) in the x-direction. If an array, there should be one item less than the size of u along the applicable axis.
• dy (float or ndarray) – The grid spacing(s) in the y-direction. If an array, there should be one item less than the size of u along the applicable axis.
• lats ((M, N) ndarray) – latitudes of the wind data
• axis (int, optional) – The axis corresponding to the vertical dimension in the potential temperature and pressure arrays, defaults to 0, the first dimension.

Returns:

(M, N) ndarray – baroclinic potential vorticity

Notes

The same formula is used for isobaric and isentropic PV analysis. Provide winds for vorticity calculations on the desired isobaric or isentropic surface. Three layers of pressure/potential temperature are required in order to calculate the vertical derivative (one above and below the desired surface).