HowTo: Run an aquaplanet simulation

The aquaplanet configuration

The aquaplanet configuration is a simpler setup than a usual simulation of the Earth's atmosphere in that idealized initial and boundary conditions are used: no topography and imposed surface temperatures over the whole globe (hence the "aqua"). Apart from this, the full physics package is used, just like in a "regular" LMDZ simulation.

aquaplanet parameters

In practice setting up an aquaplanet simulation is simpler as one may start without initial condition files (start.nc and startfi.nc). This requires setting

read_start=n

in run.def

In addition one must specify a value of iflag_phys between 101 and 114 to trigger the aquaplanet mode, e.g.

iflag_phys=101

This will automatically generate initial conditions and trigger the generation of a limit.nc file adapted to the aquaplanet setup. The values of surface temperature that will be put in the limit.nc file depend on iflag_phys (see routines iniaqua and profil_sst in libf/phylmd/phyaqua_mod.F90).

Good to know

Note that to continue an aquaplanet simulation (i.e. using restart.nc and restartphy.nc files from a previous aquaplanet simulation) one should revert iflag_phys to 1.

03/12/2021