2.2. Some key switches¶
There are many variables that act together to determine how a run of JULES is set up and these are covered in detail in The JULES namelist files. Additionally, configurations illustrate suitable combinations of options. Here we highlight a few key switches that select broad areas of science, particularly for the benefit of new users.
The phenology model for natural vegetation can be enabled using
l_phenol which uses the leaf turnover rate to calculate a time-varying Leaf Area Index (LAI).
To simulate carbon stocks in natural vegetation, the TRIFFID dynamic vegetation model can be enabled via the switch
l_triffid. When TRIFFID is on, competition between tiles is switched on with
l_veg_compete and the effect of nitrogen on vegetation growth is enabled via
The crop model, which is simulates phenology and carbon stocks in crops, can be switched on by setting the number of crop tiles
ncpft to a non-zero value.
The crop model and TRIFFID cannot currently be used together. To simulate agricultural areas within TRIFFID, a fraction of the gridbox can be reserved for agricultural Plant Functional Types (PFTs) (as defined by
crop_io > 0). Agricultural PFT competition and a representation of harvest carbon can be switched on with
To simulate carbon and nitrogen stocks in the soil, the 4-pool model should be selected by setting
soil_bgc_model = 2. This option adds prognostic soil pools and must be used with the TRIFFID vegetation model. If TRIFFID is not used, prescribed soil pools must be invoked via
soil_bgc_model = 1. Layered soil pools are used if
l_layeredc = .TRUE..
A multi-layer snow model can be selected using
nsmax. Parameterisations of surface and subsurface runoff generation are controlled using
l_pdm, while the routing of water in rivers uses