Read first here: https://forge.ipsl.jussieu.fr/igcmg_doc/wiki/Doc/Models/LMDZ

Setting up a zoomed simulation is basically telling the model to use a different grid.  The standard grid is now 144x142x39 (longitude x latitude x atmospheric levels).  If you have developed a zoomed grid which has the same dimensions as that, you can follow the instructions on a different page to install and compile the model.  After having done that, you can skip to the Nudge section on this page.  If someone else has given you a grid of a different size, you should start from the top here.  I am going to assume that you are interested in using a grid which is half a degree resolution over Europe, which is 128x118x39.

= Set up for Zoom over Europe in coupled mode LMDZOR =

 * Install LMDZOR_v5.2 (using the trunk or one of the branches, as described elsewhere) or LMDZOR_v5 (tag 1.9.5 or 1.9.6)
 * Compile in modipsl/config/LMDZOR_v5.2 using '''gmake LMD128118-L39'''
 

== Nudging ==
Activate nudging by setting ok_guide=y and add nudging files in !BoundaryFiles section List in lmdz.card.[[BR]]
"-" means to remove the line, "+" means to add the line.

{{{
 # Nugding : ok_guide=y/n
 # If ok_guide=y, add nudging files(u.nc, v.nc, hur.nc,...) in the BoundaryFiles section below.
-ok_guide=n
+ok_guide=y
}}}

ERAI nudging files for wind (u and v) have been interpolated to the zoomed grid using the method described here : [https://forge.ipsl.jussieu.fr/igcmg/wiki/platform/en/documentation/I_modeles/B_LMDZ#Interpolationofnudgefiles]
If you are not using a zoomed grid that has been used previously, you will have to do this yourself.
The years 1980 to 2011 have been done for 128x118. They are stored at TGCC here : 

{{{
/ccc/work/cont003/dsm/p86ipsl/IGCM/BC/ATM/LMDZ/LMD128118/NUDGE_FILES/ERAI
}}}

This requires a change to COMP/lmdz.card so that libIGCM knows to copy the files before the run.
"-" means to remove the line, "+" means to add the line.

{{{
 [BoundaryFiles]
-List=()
+
+List= (${R_BC}/ATM/${config_UserChoices_TagName}/${RESOL_ATM}/NUDGE_FILES/ERAI/${year}/u_${year}${month}_erai.nc, u.nc),\
+      (${R_BC}/ATM/${config_UserChoices_TagName}/${RESOL_ATM}/NUDGE_FILES/ERAI/${year}/v_${year}${month}_erai.nc, v.nc)
}}}

The following parameters for nudging result in a strong nudging outside the zoom and a small nudging inside the zoom. Change the PARAM/guide.def to the following : 

{{{
# ok_guide=y : guidage active
ok_guide=_AUTO_ : DEFFAULT = n
#
guide_u= y
guide_v= y
guide_T= n
guide_P= n
guide_Q= n
tau_min_u=0.05
tau_max_u=10.
tau_min_v=0.05
tau_max_v=10.
}}}

This means that outside the zoom the wind is nudged every 86400*0.05 seconds (about 1h12min), which is considered fairly strong but necessary for an intense zoom.  Inside the zoom, the winds are nudged every 10 days.


== Aerosols ==
The aerosols have to be interpolated to the zoomed model grid. The years 1980-2000 for HISTORIQUE run version _v5 have been done. They are found at the standard place : /ccc/work/cont003/dsm/p86ipsl/IGCM/BC/ATM/LMDZ/LMD128118/AR5/HISTORIQUE . You need to change _v3 into _v5 in lmdz.card to use these files. 
[[BR]]
"-" means to remove the line, "+" means to add the line.

{{{
 #List=
 #      (/dmnfs/cont003/p86ghatt/IGCM_OUT/LMDZOR/NUDGING-CORDEX-AFR/${year}${month}/u.nc, u.nc),\
 #      (/dmnfs/cont003/p86ghatt/IGCM_OUT/LMDZOR/NUDGING-CORDEX-AFR/${year}${month}/v.nc, v.nc)
 	    (${R_BC}/ATM/${config_UserChoices_TagName}/IPCC_AR5/HISTORIQUE/N2O_1765_2005.txt, N2O.txt),\
 	    (${R_BC}/ATM/${config_UserChoices_TagName}/IPCC_AR5/HISTORIQUE/CFC11_1765_2005.txt, CFC11.txt),\
 	    (${R_BC}/ATM/${config_UserChoices_TagName}/IPCC_AR5/HISTORIQUE/CFC12_1765_2005.txt, CFC12.txt),\
-	    (${R_BC}/ATM/${config_UserChoices_TagName}/${RESOL_ATM}/AR5/HISTORIQUE/aerosols_11YearsClim_1855_v3.nc, aerosols.nat.nc)
+	    (${R_BC}/ATM/${config_UserChoices_TagName}/${RESOL_ATM}/AR5/HISTORIQUE/aerosols_11YearsClim_1860_v5.nc, aerosols.nat.nc)
 
 [SmoothFiles]
 # With AR5 aerosols (including ASSO4M(=SO4), CSSO4M, AIBCM, ASBCM, AIPOMM, ASPOMM, ASSSM, CSSSM, SSSSM, CIDUSTM)
 # With AR5 ozone(tropo + strato from LMDZOR-INCA-REPROBUS simulations)
 List=   (${ARCHIVE}/IGCM_OUT/LMDZ/${CREATE}/ATM/Output/Boundary/${CREATE}_${year}_limit.nc,          limit.nc,           1:12:),\
-        (${R_BC}/ATM/${config_UserChoices_TagName}/${RESOL_ATM}/AR5/HISTORIQUE/aerosols_11YearsClim_${year}_v3.nc, aerosols${year}.nc, 1:12:), \
+        (${R_BC}/ATM/${config_UserChoices_TagName}/${RESOL_ATM}/AR5/HISTORIQUE/aerosols_11YearsClim_${year}_v5.nc, aerosols${year}.nc, 1:12:), \
         (${ARCHIVE}/IGCM_OUT/LMDZ/${CREATE}/ATM/Output/Boundary/${CREATE}_${year}_climoz_LMDZ.nc,    climoz_LMDZ.nc,     1:12:)
}}} 

It is also possible to deactivate aerosol forcing. To do so, remove the lines containing aerosols_ from the List section and change lmdz.card to the following : 

{{{
# manage radiative aerosol effect and ozone 
flag_aerosol=0
ok_ade=n
ok_aie=n
aerosol_couple=n
read_climoz=0
ok_cdnc=n
}}}

NB : read_climoz=0 will also deactivate the reading of ozone. Ozone is regridded by the job LMDZ/CREATE_ so this is not necessary to deactivate. 


== How to run ==

This should be identical to doing any other coupled run.  If it's not, contact someone who is doing coupled runs with a zoomed grid and tell them this page is incomplete and/or wrong.

== Further reading ==
See the page http://forge.ipsl.jussieu.fr/orchidee/wiki/HowTo/NewGrid for more information about grids.

http://forge.ipsl.jussieu.fr/igcmg_doc/wiki/DocImodelBlmdz#Simulationwithnudging also has some more information about nudging.