Synthetic gravity waves

This python package facilitates the creation of 2D synthetic atmospheric gravity-wave wave-packets mimicking the vertical velocity structure seen in numerical weather prediction models as fixed height or pressure levels.

Installation and usage

Install the package with pip from pypi.org

python -m pip install synthetic_gravity_waves

And the import synthetic_gravity_waves and use it to create a uniformly gridded vertical velocity field with synthetic gravity wave wave-packets:

import synthetic_gravity_waves as sgw

phi = sgw.make_synthetic_gravity_wave_composite(N=512, r_sigma=10.0, r0=80.0, lw0=10.0)

w0 = 5.0  # max characteristc vertical velocity [m/s]
w = phi * w0

# w now contains synthetic gravity wave packets with amplitude between -w0 and w0

Method

The method uses a point-sampling method based on the Poisson-disc sampling algorithm by Robert Bridson, but modified to in place of using a 2D density field to define the local density of points the spatial separation between points is sampled from a Gaussian distribution with mean r0 and standard deviation r_sigma. The sampling is done on a grid of shape (N, N). At the sampled points 2D Gaussians envelopes modulating plane-parallel carrier waves with a controllable characterisc wavelength.

See [notebooks/usage.ipynb] for details.

References

• Fast Poisson disk sampling in arbitrary dimensions , Bridson, R. (2007). Fast Poisson disk sampling in arbitrary dimensions. SIGGRAPH sketches, 10(1), 1. PDF

• poissonDiskSampling by Adrian Bittner.