monarchs.physics.virtual_lid.virtual_lid_development

monarchs.physics.virtual_lid.virtual_lid_development(cell, dt, met_data, turbulent_flux_upper)

When a lake undergoes freezing from the top due to the surface conditions, a lid forms. However, the depth of this lid can oscillate significantly during the initial stages of formation, including disappearing entirely. To model this, we assume that the model is in a “virtual lid” state while the lid depth is less than 0.1 m. This function tracks the development of this virtual lid, and switches the model into a non-lid state if it melts entirely, or into a true lid state if the lid depth exceeds the 0.1 m depth threshold.

This virtual lid, unlike the “true” lid, has a single value for its temperature (cell.v_lid_temperature), rather than a vertical profile. The function handles freezing and melting of this virtual lid from the top and bottom.

As with many other functions, this operates on a single column.

Called in timestep_loop.

Parameters:

• cell (numpy structured array) – Element of the model grid we are operating on.

• dt (int) – Number of seconds in the timestep, very like 3600 (i.e. 1h) [s]

• lw_in (float) – Incoming longwave radiation. [W m^-2].

• sw_in (float) – Incoming shortwave (solar) radiation. [W m^-2].

• air_temp (float) – Surface-layer air temperature. [K].

• p_air (float) – Surface-layer air pressure. [hPa].

• dew_point_temperature (float) – Dew-point temperature at the surface. [K]

• wind (float) – Wind speed. [m s^-1].

Return type:

None (amends cell inplace)