pvtend.ddx

pvtend.ddx(field: ndarray, dx_arr: ndarray, periodic: bool = True) → ndarray

Zonal derivative ∂f/∂x with periodic wrapping.

Uses centred finite differences in the interior. At the zonal boundaries the field wraps around the globe when periodic is True (default); otherwise one-sided differences are applied.

Parameters:

• field – 2-D array (nlat, nlon) or 3-D (nlev, nlat, nlon).

• dx_arr – Zonal grid spacing per latitude [m], shape (nlat,).

• periodic – If True, wrap zonally (col 0 ↔ col -1).

Returns:

Same shape as field, in units of [field_units / m].