Surface Flux

The surface_flux_nml only ever needs to be specified if mixed_layer_bc = .true. in idealized_moist_phys_nml. It contains options which deal with the exchange of heat, momentum at the surface, including the difference between ocean and land. It is described on Isca's website and is used in the realistic continents example script.
Some of the most common options are described below:

Options

Land

There are 4 ways that land is implemented in Isca.

land_humidity_factor

float
Factor that multiplies the surface specific humidity over land.
This is included to make land dry. If it is equal to 1, land behaves like ocean.
If it is between 0 and 1, this will decrease the evaporative heat flux in areas of land.
The evaporative flux formula is given on Isca's website.
Only ever required if land_option is not none.

Instability

Note that this can lead to sign changes in the evaporative flux, and we find this becomes unstable over very shallow mixed layer depths.

Default: 1.0

land_evap_prefactor

float
Factor that multiplies the evaporative flux over land.
This is included to make land dry. If it is equal to 1, land behaves like ocean.
If it is between 0 and 1, this will decrease the evaporative heat flux in areas of land.
The evaporative flux formula is given on Isca's website.
Only ever required if land_option is not none.

Stability

This formulation avoids sign changes in the evaporative flux and remains stable over very shallow mixed layer depths.

Using with bucket model

With my adjustment to the surface_flux.F90 source code, you can use this prefactor when using the bucket model.

It acts like the vegetation prefactor, \(C_V\) in pietschnig_2021.

Default: 1.0