Radiation models

PALM offer a built-in simple and fast radiation model for clear sky conditions. Moreover, an interface allows for using the ​RRTMG code.

Constant radiation

Not really being a radiation model, this option allows for prescribing the net radiation at the surface (e.g. as driving for the [wiki;doc/tec/lsm land surface model]). The user can use the user interface in order to modify the net radiation during the run. For more information, see doc/app/radpar.

Simple clear sky radiation

A simple clear sky radiation model can be used for simulations without clouds and highly-parametrized radiation fluxes.

RRTMG

Since r1585 PALM can be used in combination with the ​RRTMG radiation code. The RRTMG source code is shipped along with PALM, but it is not part of the model (this eans that RRTMG is put under a difference licence than PALM, which e.g. forbids reselling of the code). Unlike most embedded modules in PALM, the RRTMG is thus used as external library and linked to the default PALM code. This in turn means that RRTMG must be installed in advance on the host where PALM shall be executed. The next section explains the installation of RRTMG and how to use it in PALM.

Installation

The RRTMG source code for creating an external library can be found under trunk/LIB/rrtmg. It is accompanied by an installation script called install_rrtmg​. In order to install RRTMG, perform the following steps:

1. Copy all files from trunk/LIB/rrtmg to the host where PALM/RRTMG shall be executed.
2. Open install_rrtmg​ and modify the following lines:

    compiler_name="mpif90"
    fopts="-fltconsistency -O3 -cpp -r8 -nbs -convert little_endian -I /muksoft/packages/netcdf/4_intel/include"
    fopts_trace="-fpe0 -C -check nooutput_conversion -debug -traceback -g -w -xT -O0 -ftz -fno-alias -no-prec-div -no-prec-sqrt -ip -nbs -convert little_endian -diag-disable 8290,8291 -I /muksoft/packages/netcdf/4_intel/include"
    install_path="$HOME/palm/rrtmg"
    compile_static=true
    compile_shared=true
    compile_static_debug=false
    compile_shared_debug=false
   

   For a proper configuration, see your [browse:palm/trunk?order=name#SCRIPTS .mrun.config] file for the respective computer architecture where RRTMG shall be installed. fopts_trace is only required if you want to have debug options enabled. Use the switch parameters compile_static=true, compile_shared=true, compile_static_debug=false, and compile_shared_debug=false to set flags for compilation of RRTMG as static library, shared library (recommended), static library with debug options (recommended), and shared library with debug options, respectively. Save your changes.

3. Execute install_rrtmg​ with option "-p", which defines the path where the library shall be installed. E.g.:

   install_rrtmg -p $HOME/lib/rrtmg
   

4. Open your .mrun.config file and add -D__rrtmg to %cpp_options of the host where PALM/RRTMG shall be used.

Also add the following line to the list of input files:

rrtmg_lw.nc              in:locopt     d3#:d3f  $base_data/$fname/INPUT    _rlw nc
rrtmg_sw.nc              in:locopt     d3#:d3f  $base_data/$fname/INPUT    _rsw nc
RAD_SND_DATA             in:locopt     d3#:d3f  $base_data/$fname/INPUT    _rsnd nc

5. Recompile PALM for the respective host.