Initial Conditions

Preconfigured initial conditions and initial condition helpers.

barotropic.init.gaussian_jet(grid, time=0.0, amplitude=20.0, center_lat=45.0, stdev_lat=5.0)

A bell-shaped, zonally-symmetric zonal jet.

Parameters:

• grid (Grid) – Grid specification.

• time (number | datetime) – Valid time.

• amplitude (number) – Peak zonal wind at the center of the jet in m/s.

• center_lat (number) – Center of the jet in degrees.

• stdev_lat (number) – Standard deviation of the jet in degrees.

Returns:

New State instance.

A linear wind profile in latitude is added to zero wind speeds at both poles.

barotropic.init.held_1985(grid, time=0.0, A=25.0, B=30.0, C=300.0)

Zonal wind profile similar to that of the upper troposphere.

Parameters:

• grid (Grid) – Grid specification.

• time (number | datetime) – Valid time.

• A (number) – Coefficient for cos-term.

• B (number) – Coefficient for cos³-term.

• C (number) – Coefficient for cos⁶sin²-term.

Returns:

New State instance.

Introduced by Held (1985), also used by Held and Phillips (1987) and Ghinassi et al. (2018).

barotropic.init.motionless(grid, time=0.0)

A motionless state.

Parameters:

• grid (Grid) – Grid specification.

• time (number | datetime) – Valid time.

Returns:

New State instance.

barotropic.init.solid_body_rotation(grid, time=0.0, amplitude=15.0)

A cosine-shaped, zonally-symmetric zonal wind profile.

Parameters:

• grid (Grid) – Grid specification.

• time (number | datetime) – Valid time.

• amplitude (number) – Peak zonal wind speed at the equator in m/s.

Returns:

New State instance.

barotropic.init.zonally_symmetric(grid, time=0.0, u=None, pv=None)

Turn a given zonal profile of zonal wind or PV into a full 2D-state.

Parameters:

• grid (Grid) – Grid specification.

• time (number | datetime) – Valid time.

• u (array) – Meridional profile of the zonal wind.

• pv (array) – Meridional profile of the potential vorticity.

Returns:

New State instance.

u xor pv must be specified.