def METHOD_NAME(self):
    """Creates wind-speed, height, veg roughness and mask 2D arrays."""
    n_x, n_y = 4, 4  # Set array dimensions.
    # Wind speed=u_href=10m/s  Height=h_ref=20m
    self.u_href = np.full([n_y, n_x], 10, dtype=float)
    self.h_ref = np.full([n_y, n_x], 20, dtype=float)
    # Vegetative roughness = 0.5m
    self.z_0 = np.full([n_y, n_x], 0.5, dtype=float)
    # Mask for land/sea - True for land-points, false for sea.
    self.mask = np.full([n_y, n_x], False, dtype=bool)
    # Mask has 'land' in centre bounded by sea points.
    self.mask[1 : n_y - 1, 1 : n_x - 1] = True