how to modify MPTABLE.TBL?

[wonseok ko]

Hello i have a few questions about modifying 'MPTABLE.TBL'

I modfiy 'MFSNO' value in 'MPTABLE.TBL'('WRF4.3/run/MPTABLE.TBL') and recompile WRF.

However, there is no chanage in the values of WRF result file.s

Is there any wrong access with this process?

Thank you for reading.

 

[Ming Chen]

It seems that this variable is never used in NoahMP, which explains why it has no impact on the results.

 

[wonseok ko]

Is the MFSNO that appears on line 1987 of module_sf_noahmplsm.F unrelated to the module_sf_noahmplsm.F and NoahMP modules?

 

[Ming Chen]

Hi,
Thank you for the update. It is my fault that I didn't find this variable, --- the WRF version I checked out doesn't include noahmp.

Did you look at your wrfout files and check whether there is snow produced ?

When you say 'there is no change in wrf results', do you mean the results are identical?

 

[wonseok ko]

Thank you for answer.

Did you look at your wrfout files and check whether there is snow produced ?
yes, we confirmed that snow was produced in wrf.

When you say 'there is no change in wrf results', do you mean the results are identical?
Yes, we compared the base WRF result with the WRF result after changing the MFSNO value in MPTABLE using ncdiff and found them to be identical.

 

[Ming Chen]

Thank you for the update. We will look into this issue and get back to you once we figure out the reason.

 

[cenlinhe]

Hi, MFSNO typically has a large impact on snow cover simulations in Noah-MP particularly for snow ablation, but the impact would be small during middle winter season where SCF is already 100%. Please double check your SNOWC variable to see if it is already 100% all the time during your simulation period. Also, how much did you change MFSNO (i.e., values before and after your changes) and for what vegetation types? This is also related to vegetation type over your study domain. Also, make sure you are modifying the MFSNO in the right land type section of MPTABLE.TBL. It has two sections, one for USGS land type and the other one is MODIS land type.

 

[wonseok ko]

Hi, Thank you for your response.

1. Please double-check the SNOWC variable to see if it is already 100% throughout your simulation period.
Our check result:
In our WRF output file, the SNOWC value ranges from 0.2 to 0.5.

2. How much did you change the MFSNO value?
Please provide the values before and after the changes and specify which vegetation types were affected.
Our modification:
We changed the MFSNO value from 3.0 to 1.0 for the Cropland/Grassland Mosaic (number 5).

3. Ensure you are modifying the MFSNO in the correct land type section of the MPTABLE.TBL file.
The MPTABLE.TBL file has two sections: one for USGS land types and another for MODIS land types. Please verify that you edited the MFSNO value in the correct section.
Our action:
We modified the MFSNO value in the USGS land type section. Please check the attached MPTABLE file.

Thank you.

 

[cenlinhe]

This is weird. Is the grid point for SNOWC you checked also Cropland/Grassland Mosaic? Could you please also provide your wrfinput file?

 

[cenlinhe]

also, for your future simulations, if you only modify the *.TBL table values under run directory, you do not need to recompile WRF source code, just directly run wrf.exe after modifying the table parameter values.

 

[wonseok ko]

Thank you for answer.

We changed the MFSNO value and ran WRF, which resulted in differences in the output.
By modifying the MPTBL and running it without recompiling, the issue was resolved.

Thank you.