pydda.cost_functions.calculate_echo_top_mask#

pydda.cost_functions.calculate_echo_top_mask(vrs, z, above=2.0)[source]#

Finds the grid points that lie above the echo top, i.e. the points above above km at which none of the radars report a valid radial velocity.

Holding w fixed at these points imposes an impermeability condition at the echo top rather than at the (arbitrary) top of the analysis domain. See Thompson et al. (2026), https://doi.org/10.5194/egusphere-2026-4631.

Parameters:

  • vrs (list of float arrays) – List of radial velocities from each radar. Points without a valid observation are expected to be filled with a large negative number (-9999.0 in PyDDA’s retrievals).

  • z (float array) – Heights of the grid points in m. This must broadcast against the members of vrs, i.e. the 3D point_z field of the Grid.

  • above (float) – Minimum height of the impermeable layer in km. The condition is never applied below this level, so that clear air near the surface does not pin w to its first guess.

Returns:

mask (3D bool array) – True wherever the impermeability condition is to be applied.