frontogenesis

metpy.calc.frontogenesis(thta, u, v, dx, dy, dim_order='yx')

Calculate the 2D kinematic frontogenesis of a temperature field.

The implementation is a form of the Petterssen Frontogenesis and uses the formula outlined in [Bluestein1993] pg.248-253.

\[F=\frac{1}{2}\left|\nabla \theta\right|[D cos(2\beta)-\delta]\]

• \(F\) is 2D kinematic frontogenesis
• \(\theta\) is potential temperature
• \(D\) is the total deformation
• \(\beta\) is the angle between the axis of dilitation and the isentropes
• \(\delta\) is the divergence

Parameters:

• thta ((M, N) ndarray) – Potential temperature
• 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.
• dim_order (str or None, optional) – The ordering of dimensions in passed in arrays. Can be one of None, 'xy', or 'yx'. 'xy' indicates that the dimension corresponding to x is the leading dimension, followed by y. 'yx' indicates that x is the last dimension, preceded by y. None indicates that the default ordering should be assumed, which is ‘yx’. Can only be passed as a keyword argument, i.e. func(…, dim_order=’xy’).

Returns:

(M, N) ndarray – 2D Frontogenesis in [temperature units]/m/s

Notes

If inputs have more than two dimensions, they are assumed to have either leading dimensions of (x, y) or trailing dimensions of (y, x), depending on the value of dim_order.

Conversion factor to go from [temperature units]/m/s to [temperature units/100km/3h] \(1.08e4*1.e5\)