====== Advanced configuration of NorESM2 ======

**NOTE THAT THE COMPSETS MENTIONED IN THIS EXAMPLE ARE NO LONGER MAINTAINED! THE GENERAL EXPLANATION AND IDEAS ARE STILL VALID!
**
===== Creating a new compset =====

The essential file to edit is 
<file>
~/noresm/scripts/ccsm_utils/Case.template/config_compsets.xml
</file>

This examples shows how to simply add a to the "F_AMIP_CAM5" compset:

Under "<!-- F compsets -->", add

<file>
<COMPSET sname="F_AMIP_CAM5-OSLO"     alias="FAMIPOSLO"  >AMIP_CAM5%OSLO_CLM40%SP_CICE%PRES_DOCN%DOM_RTM_SGLC_SWAV</COMPSET>
</file>

The "CAM5%OSLO" options have to be defined, so a line like this is needed:

<file>
<CAM_CONFIG_OPTS compset="_CAM5%OSLO"     >-phys cam5 -cam_oslo aerlife</CAM_CONFIG_OPTS>
</file>

The compset needs a description, we also need the line
<file>
<desc compset="_CAM5%OSLO">cam 5 physcs and oslo aerosols</desc> 
</file>

We could also define a specific use-case (namelist) for our compset. This would need a line like:
<file>
 <CAM_NML_USE_CASE compset="_CAM5%OSLO"        >my_namelist</CAM_NML_USE_CASE>
</file>

This would only work if the file my_namelist.xml exists as 
<file>
noresm/models/atm/cam/bld/namelist_files/use_cases/my_namelist.xml
</file>


===== Setting up a case with the new compset and building the model =====

It should now be possible to create a new case directory, which we here name FAMIPOSLOtst
and configure with 1 degree horizontal atmospheric resolution;

<file>
./create_newcase -case ../cases/FAMIPOSLOtst -compset FAMIPOSLO -mach hexagon -res f09_f09
</file>

and finally set up and compile the model:
<file>
cd ../cases/FAMIPOSLOtst
</file>

<file>
./cesm_setup
</file>

<file>
./FAMIPOSLOtst.build
</file>

===== Why does it work to change config_compsets.xml ?   =====

In NorESM there are 3 new config-options for CAM:  
  * -cam-oslo aerlife (turns on transport of oslo tracers)
  * -cam-oslo dirind  (also turns on interaction with radiation)
  * -cam-oslo warmclouds (also turns on interaction with warm clouds)

They change number of tracers and turn on different preprocessor flags in in a perl script called "configure", see: 
<file>
models/atm/cam/bld/configure
</file>

To understand the implementation do:
<file>
svn diff -r 202 models/atm/cam/bld/configure 
</file>

The new oslo-options also need to be defined, see 
<file>
models/atm/cam/bld/config_files/definition.xml
</file>

To see how these new options were added, do:
<file>
svn diff -r 202 models/atm/cam/bld/config_files/definition.xml
</file>


===== Configure nudging =====

==== Create the met-data ====

First run the model to produce 6 hourly data. The following namelists are needed:

<file>
user_nl_cam
&camexp
mfilt           = 1,  4,
nhtfrq          = 0,  -6,
avgflag_pertape ='A','I',
fincl2          = 'PS','U','V','TAUX','TAUY','FSDS','TS','T','Q','PHIS','QFLX','SHFLX'
</file>

<file>
user_nl_clm
&clmexp
hist_mfilt             = 1,4
hist_nhtfrq            = 0,-6
hist_avgflag_pertape   = 'A','I'
hist_fincl2            = 'SNOWDP','H2OSNO','H2OSOI'
</file>

==== Use the met-data in another run ====

First create a compset which has the configure-option "-offline_dyn".  Check in config_compsets.xml which compsets have this configure-option added. See for example the compset NFAMIPNUDGEPTAERO in https://svn.met.no/NorESM/noresm/branches/featureCAM5-OsloDevelopment_trunk2.0-1/noresm/scripts/ccsm_utils/Case.template/config_compsets.xml

Then use this compset to create a case. You need the following user-input (for example in your user_nl_cam)

<file>
&metdata_nl
met_data_file='/work/shared/noresm/inputForNudging/FAMIPC5NudgeOut/atm/hist/FAMIPC5NudgeOut.cam.h1.1979-01-01-00000.nc'
met_filenames_list = '/work/shared/noresm/inputForNudging/FAMIPC5NudgeOut/atm/hist/fileList.txt'
</file>

This info can be added directly in a use_case which you associate with the compset created (see e.g. 2000_cam5_oslonudge.xml) 

where met_data_file is the first met-data file to read, and met_filenames_list is a list of the following met-data. The first lines of the file should look something like this (guess what the rest of the file should look like? 8-o: ) 
<file>
/work/shared/noresm/inputForNudging/FAMIPC5NudgeOut/atm/hist/FAMIPC5NudgeOut.cam.h1.1979-01-01-00000.nc
/work/shared/noresm/inputForNudging/FAMIPC5NudgeOut/atm/hist/FAMIPC5NudgeOut.cam.h1.1979-01-02-00000.nc
/work/shared/noresm/inputForNudging/FAMIPC5NudgeOut/atm/hist/FAMIPC5NudgeOut.cam.h1.1979-01-03-00000.nc
</file>

This file can be created at the place where you put the metdata with this command: 
<file>
alfgr@hexagon-4:/work/shared/noresm/inputForNudging/FAMIPC5NudgeOut/atm/hist> ls -d -1 $PWD/*.h1.*.nc > fileList.txt
</file>

==== Namelist options ====
When looking at aerosol indirect effects, it's recommended to nudge only U, V and PS:
<file>
&metdata_nl
 met_nudge_only_uvps = .true.
</file>

Choose relaxation time (hours). Use the same time as dt in met_data_file:
<file>
&metdata_nl
 met_rlx_time = 6
</file>


==== Nudge to ERA-interim reanalysis ====
Link to ERA-interim metdata instead of model produced metdata. Remember to choose the files corresponding to your resolution (examples below are for f09_f09 and 32 levels in the vertical):
<file>
&metdata_nl
 met_data_file = '/work/shared/noresm/inputdata/noresm-only/inputForNudging/ERA_f09f09_30L_days/2001-01-01.nc'
 met_filenames_list = '/work/shared/noresm/inputdata/noresm-only/inputForNudging/ERA_f09f09_30L_days/fileList2001-2015.txt'
</file>

Add also the ERA-topography (no matter which fields you are nudging):
<file>
&cam_inparm
 bnd_topo = '/work/shared/noresm/inputdata/noresm-only/inputForNudging/ERA_f09f09_30L_days/ERA_bnd_topo.nc'
</file>