polaris.tasks.ocean.horiz_press_grad.finite_volume.shift_increments

polaris.tasks.ocean.horiz_press_grad.finite_volume.shift_increments(ds: Dataset) → Dataset

The two increments of [gamma-increments], for the D7 measurement.

Deliverable D7 of the plan asks how much precision the accumulation saves, and the quantitative form of “no large-number cancellation occurs” is the ratio of the largest increment to the largest of Delta_e Z – the quantity [centered-shift] differences directly.

Parameters:

ds (xarray.Dataset) – The two-column state, as for centered_shift().

Returns:

increments (xarray.Dataset) – within_layer (Gamma^+_k - Gamma_k), between_layers (Gamma_{k+1} - Gamma^+_k), and delta_z_interface (Delta_e Z at interfaces) to scale them against. All in m.