Spectral Dynamics

The spectral_dynamics_nml contains options relating to Isca's spectral dynamical core. The Frierson example script uses this namelist and some of the diagnostics.
Some of the most common options are described below:

Options

num_levels

integer
The number of pressure coordinates i.e. number of vertical coordinates.
Default: 18

vert_coord_option

string
How to specify the vertical coordinates, there are two options:

• even_sigma: Levels are equally separated in \(\sigma\) such that there are num_levels levels.
  
• uneven_sigma: Not really sure what this does but it is an option.

• input: Each coordinate is explicitly specified using the vert_coordinate_nml namelist.
  

  vert_coordinate_nml

  In this case, the namelist vert_coordinate_nml needs to be specified through two options:

  • bk - The \(\sigma\) coordinates. There should be num_levels+1 of these including \(0\) and \(1\).
  • pk - The corresponding pressure coordinates. Again, there should be num_levels+1 of these. If they are all set to \(0\), they will be computed automatically.

  For an example using this , see the the frierson_test_case.

Default: even_sigma

Diagnostics

The diagnostics for this module can be specified using the module_name of dynamics in the diagnostic table file. Some available diagnostics are listed on Isca's website. Some of the more common ones are also given below:

ps

Surface pressure.
Dimensions: time, lat, lon
Units: \(Pa\)

bk

Vertical coordinate \(\sigma\) values.
Dimensions: pressure
Units: \(Pa\)

pk

Vertical coordinate pressure values.
Dimensions: pressure
Units: \(Pa\)

sphum

Specific humidity.
Dimensions: time, lat, lon, pressure
Units: \(kg/kg\)

temp

Temperature.
Dimensions: time, lat, lon, pressure
Units: \(K\)

ucomp

Zonal component of the horizontal winds.
Dimensions: time, lat, lon, pressure
Units: \(ms^{-1}\)

vcomp

Meridional component of the horizontal winds.
Dimensions: time, lat, lon, pressure
Units: \(ms^{-1}\)

omega

Vertical velocity.
Dimensions: time, lat, lon, pressure
Units: \(Pas^{-1}\)

vor

Vorticity.
Dimensions: time, lat, lon, pressure
Units: \(s^{-1}\)

div

Divergence.
Dimensions: time, lat, lon, pressure
Units: \(s^{-1}\)

height

Geopotential height at full model levels.
Dimensions: time, lat, lon, pressure
Units: \(m\)