Module terrain 

Diagnostic mass-consistent terrain wind (NOABL/CONMESS-style).

A terrain height grid (in metres) plus a background WindField and optional surface wind monitors become a terrain-adjusted field: each fixed above-ground level is adjusted independently to satisfy 2-D horizontal mass conservation (div(u) = 0 with u = u0 − ∇φ), so flow is deflected over and around terrain. This is the cheap diagnostic tier of terrain flow, not a full CFD solve. Entirely offline and deterministic.

Structs

HeightGrid

Terrain heights on an axis-aligned, uniform grid in metres. Row-major: heights[i * ncols + j] is column j (east), row i (north). Position y is up; the grid lies in the x–z plane.

TerrainFlowField

A diagnostic terrain-adjusted wind field.