stilt.observations.plume_polygon#

stilt.observations.plume_polygon(longitudes, latitudes, *, threshold=0.1, bandwidth=(0.1, 0.15), n=100)[source]#

Return the plume outline from forward-run particle positions at overpass time.

The plume is the region where the kernel density of the positions (kernel_density()) is at least threshold times its maximum. The defaults are X-STILT’s (td = 0.1, h = c(0.1, 0.15), n = 100).

Parameters:

  • longitudes (TypeAliasType) – Positions of every particle row in the overpass window, pooled over all the forward runs for that overpass, in degrees.

  • latitudes (TypeAliasType) – Positions of every particle row in the overpass window, pooled over all the forward runs for that overpass, in degrees.

  • threshold (float) – Fraction of the maximum density that the outline follows. A larger value gives a tighter plume.

  • bandwidth (tuple[float, float]) – Kernel bandwidth in longitude and latitude, in degrees. A larger value gives a smoother plume.

  • n (int) – Number of density grid points in each direction.

Return type:

Plume