Modified topography in MPAS

J

jocegue

New member
Hi, I am conducting some experiments in the East Pacific, and I would like to flatten the Andes Mountains in South America. I'm wondering about the best approach to do this in MPAS.
In my mind, the easiest method (probably because I'm not familiar with the binary GMTED10 files) might be to modify the static NetCDF file with, for example, xarray in Python, but I don't know if that would have any issues along the way. If that’s not recommended, I assume modifying the binary GMTED10 files might be better. Does anyone have thoughts or suggestions on this?

Thanks,

Jose A. Ocegueda Sanchez
Ph.D student in Atmospheric Sciences.
 
I would suggest that you modify terrain data in your static.nc file (the one you generated by running init_atmopshere_model).
Both NCL and python can be used.
 
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Apologies for bumping this old thread but I figured it would be the most appropriate place to ask...

When modifying terrain in the static.nc file, say to adjust elevation only, is it sufficient to modify only the ter variable? It seems to me, looking through the variables in the static.nc file, that you would actually need to also adjust the sub-grid scale orography (variables var2d, con, oa1, oa2, oa3, oa4, ol1, ol2, ol3, ol4, and potentially others). Is that correct? If so, how would the calculation of those fields be done? Would it be easier/recommended to edit the binary files so that WPS can do all that processing instead?
 
@ kalassak,

Variables var2d, con, oa1, oa2, oa3, oa4, ol1, ol2, ol3, ol4 etc. are only used when you run MPAS with the GWD option. Otherwise you don't need to worry for them.

However, if you intend to run with GWD option, these variables should be modified if your terrain data are changed. Note that MPAS calculates these variables based on global 'tiles' of terrain height ( see mpas_init_atm_gwd.F). This implies that you need to modify the codes so that your own terrain data can be used.

If you intend to run MPAS with GWD option on, and you modify terrain but keep these GWD-related variables unchanged, I am not sure how large the impact could be. Please refer to the literature and hopefully you can find some helpful information.
 
Oh, I see, thank you!

This brings up a related question. How many of the land use/veg/soil/albedo variables (mminlu, ivgtyp, isltyp, snoalb, soiltemp, greenfrac, shdmin, shdmax, albedo12m) are used in the default running of MPAS? Previously I would have assumed all of them but now I'm not sure. My project involves adjusting these fields if they are required.
 
The following static variables are required for MPAS run:
ter, landmask, mminlu, isice_lu, iswater_lu, ivgtyp, isltyp, snoalb, soiltemp, greenfrac, shdmin, shdmax, albedo12m

If you run with NoahMP, you will also need:
soilcomp, soilcl1, soilcl1-4,

If GWD is activated, you will need:
var2d, con, oa1-4, ol1-4,

These variables all are included in the initial condition. I guess you don't need to exclude them even if you don't use them in your MPAS run.
 
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