Error while running metgrid.exe with ERA5 winds data

[alugulaboyaj]

I wanted to run the WRF models with initial and boundary conditions from the NCEP GFS 25 km resolution and only winds (UV) data from the ERA5.

For that, I have completed running ungrib.exe for the NCEP GFS and ERA5 UV winds data. While running ungrib.exe, I used Vtable.GFS for NCEP GFS data and Vtable.ERA-interim.pl for the ERA5 winds data.

Generated below files after running urgrib.exe

FILE:2021-03-30_00
FILE:2021-03-30_06
FILE:2021-03-30_12
FILE:2021-03-30_18

WIND:2021-03-30_00
WIND:2021-03-30_06
WIND:2021-03-30_12
WIND:2021-03-30_18


Then, while running the metgrid.exe using the option fg_name = 'FILE','WIND', it is working for the first time step, but for the second time step, it is showing the error below.

ERROR: Error in ext_pkg_write_field

Can anyone kindly help me resolve this issue?

I have tried WPS-4.0, WPS-4.1, and WPS-4.3.2 but the problem was the same.

Thank you in advance.

Boyaj

 

[kwerner]

Hi Boyaj,
This error typically means you are missing surface data. Can you verify that the surface data from GFS is processed and in the FILE* files?

 

[alugulaboyaj]

Dear Dr. Kwerner,

Thank you for your kind response.

I have verified that the surface data from GFS is processed in the FILE* files. I tested the same FILE* files with U and V winds from the NCEP Reanalysis-II 6-hourly data, and it is working fine, and the met_em* files have been created without any error. However, I noticed differences between the ERA5 and NCEP Reanalysis-II datasets. The units are the same, but the order of pressure levels differs between these two datasets. For ERA5 data, the pressure levels start at 100 Pa, while for NCEP Reanalysis-II, the pressure levels start at 100000 Pa.

The order of ERA5 data pressure levels is as follows:
100, 200, 300, 500, 700, 1000, 2000, 3000, 5000, 7000, 10000, 12500, 15000, 17500, 20000, 22500, 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000, 77500, 80000, 82500, 85000, 87500, 90000, 92500, 95000, 97500, 100000.

The NCEP Reanalysis winds pressure levels are:
100000, 92500, 85000, 70000, 60000, 50000, 40000, 30000, 25000, 20000, 15000, 10000, 7000, 5000, 3000, 2000, 1000.

If this order of the pressure levels is a problem, then how is ungrib.exe working? I'm worried if this order of pressure levels might cause any issues or if there is any other issue while running metgrid.exe.

I shall be grateful if you could resolve my issue.

Here is a link for you to see a few of my files.

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With regards
Boyaj

 

[kwerner]

Boyaj,
Thank you so much for sharing those files. I was able to figure out the issue. The order of levels isn't causing a problem. The issue is the difference in levels between each data type. To get past this, you can use the mod_levs.exe utility (available in the wps/util directory). I found that the two data types have the following levels in common, and this is what I added to my namelist.wps before running the mod_levs.exe:

&mod_levs
press_pa = 100000, 97500, 95000, 92500, 90000, 85000, 80000, 75000, 70000, 65000, 60000, 55000, 50000, 45000, 40000, 35000, 30000, 25000, 20000, 15000, 10000, 7000, 5000, 3000, 2000, 1000, 700, 500, 300, 200, 100
/

I actually had to run this on both types of intermediate files. For e.g., I ran the following

./util/mod_levs.exe WIND:2021-03-30_00 ERA5:2021-03-30_00

./util/mod_levs.exe FILE:2021-03-30_00 GFS:2021-03-30_00

and I ran each of those for all times available.

After that, I modified the namelist to change the prefixes in the &metgrid section.

&metgrid
 fg_name = 'GFS','ERA5'

And then metgrid ran without the previous error. Let me know if this solves your issue.

 

[alugulaboyaj]

Dear Sir,

Thank you so much for your wonderful help and support in resolving my issue. Now I am able to run the metgrid.exe, and met_em* files have been created.

With best regards
Boyaj

 

[kwerner]

That is great new! Thank you for letting me know.