Additional microphysics fields for initialisation and domain boundaries

[johanneshorak]

This update adds the capability to specify additional microphysics fields that should be imported from the forcing dataset. Their behaviour is the same as for the already pre-existing optional fields such as cloud ice mixing ratio and cloud water mixing ratio. If specified these fields are also applied at the domain boundaries during the simulation. The new optional fields are:

• qrvar ... rain mixing ratio [kg/kg]
• qsvar ... snow mixing ratio [kg/kg]
• qgvar ... graupel mixing ratio [kg/kg]
• qnivar ... ice number density [1/kg]
• qnrvar ... rain number density [1/kg]

and must be specified in the var_list section of the icar options file.

Example if a WRF simulation is used as forcing dataset and the additional microphysics fields should be used: qrvar = "QRAIN", ! rain mixing ratio [kg/kg] OPTIONAL qsvar = "QSNOW", ! snow mixing ratio [kg/kg] OPTIONAL qgvar = "QGRAU", ! graupel mixing ratio [kg/kg] OPTIONAL qnivar = "NICE", ! ice number density [1/kg] OPTIONAL qnrvar = "NRAIN", ! rain number density [1/kg] OPTIONAL

The attached graphic shows the field in the WRF forcing dataset, the field as reproduced by ICAR at timestep zero, and the difference between the two.

[gutmann]

This is good, but can you re-create this as a pull request against the develop branch instead of the master branch?