pysteps.noise.motion.initialize_bps¶
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pysteps.noise.motion.
initialize_bps
(V, pixelsperkm, timestep, p_par=None, p_perp=None, randstate=None, seed=None)¶ Initialize the motion field perturbator described in [BPS2006]. For simplicity, the bias adjustment procedure described there has not been implemented. The perturbator generates a field whose magnitude increases with respect to lead time.
Parameters: - V : array_like
Array of shape (2,m,n) containing the x- and y-components of the m*n motion field to perturb.
- p_par : tuple
Tuple containing the parameters a,b and c for the standard deviation of the perturbations in the direction parallel to the motion vectors. The standard deviations are modeled by the function f_par(t) = a*t**b+c, where t is lead time. The default values are taken from [BPS2006].
- p_perp : tuple
Tuple containing the parameters a,b and c for the standard deviation of the perturbations in the direction perpendicular to the motion vectors. The standard deviations are modeled by the function f_par(t) = a*t**b+c, where t is lead time. The default values are taken from [BPS2006].
- pixelsperkm : float
Spatial resolution of the motion field (pixels/kilometer).
- timestep : float
Time step for the motion vectors (minutes).
- randstate : mtrand.RandomState
Optional random generator to use. If set to None, use numpy.random.
- seed : int
Optional seed number for the random generator.
Returns: - out : dict
A dictionary containing the perturbator that can be supplied to generate_motion_perturbations_bps.
See also