met_em files

[Satz_23]

Hi all,

I have a doubt in the met_em files generated. I'm trying to reproduce the results of the simulation from the article -"Recovery processes in a large offshore wind farm". I'm using WRF 4.4.1 and WPS 4.4 for the current simulation. I have successfully compiled the WRF and WPS with the required changes as per the paper. But after running the metgrid.exe I got fewer nc files (no. of .nc files = no. of domain * no_of_input_data_time_step). To be exact, I am using 3 domains to simulate flow feature for 3 days (6 hr interval - 13 files: fnl data from NCEP). So, metgrid.exe should generate 39 nc files (3*13). Instead, I got only one file at the beginning of the time step for domain 3 whereas I got 13 nc files each for d01 and d02. I found from this forum ((RESOLVED) Are met_em files for all time steps for inner domains necessary?) that this may not be an issue and so I went ahead with running ./real.exe.
Also, earlier when i did the same work with WRF 4.3.3 the metgrid.exe generated 39 nc files!!!
Why is it happening with different versions? Is it necessary to create the nc files - one file per time, for each domain? What if it doesn't create the required no of nc files? Will it create any issue if I run real.exe and then in wrf.exe?

Note: Attached namelist.wps and log files of geogrid, ungrib and metgrid.

 

[Ming Chen]

When you run triply nested cases, you will need all met_em.d01 files for the period of your run, you will need only a single met_em.d02 and a met_e,.d03 file at the initial time of your run. I don't think you will need all the met_em.d02 and met_em.d03 for the entire period of your integration.

 

[Satz_23]

Ok. Thank You for clarifying. May I know why WRF-4.3.3 creates one .nc file per time, for each domain (d01,d02,d03) whereas WRF-4.4.1 creates only one file for d03 and all files for d02, d01.

 

[Ming Chen]

Would you please clarify the issue? By saying one file per time, do you mean one met_em file or wrfinput file?

 

[Satz_23]

Generally, metgrid.exe will generate met_em.d0x.yyyy-mm-dd_hh:mm:ss.nc (I call this as met_em file).
In WRF-4.3.3, metgrid.exe creates met_em file for each domain and for all time steps (In my case with 3 domains and 13 times steps, there will be 39 met_em files). But, WRF-4.4.1 creates only 27 met_em files i.e, 13 files each for d01 and d02, and only one file for d03. Why this difference in generating met_em files between different versions?

 

[Ming Chen]

I suppose this is related to time options in your namelist.wps. If you specify
max_dom = 2,

start_date = '2006-08-16_12:00:00','2006-08-16_12:00:00',

end_date = '2006-08-18_12:00:00','2006-08-18_12:00:00',

Then met_em.d01 and met_em.d02 will be produced for all the times over the period 2006-08-16_12:00:00 to 2006-08-18_12:00:00

However, if you set

start_date = '2006-08-16_12:00:00','2006-08-16_12:00:00',

end_date = '2006-08-18_12:00:00','2006-08-16_12:00:00',

Then met_em.d01 will be produced for all the times, but met_em.d02 is only created for the time 2006-08-16_12:00:00

 

[Satz_23]

Thank You Ming Chem