grib2arl ERA5 .grb files to .arl processing error due to inconsistent vertical levels?

danavitski · Post by **danavitski** » July 10th, 2023, 9:06 am

Dear HYSPLIT forum,

I am trying to obtain STILT-compatible formatted ERA5 reanalysis meteorological fields, and have been trying to do so using a generic ECMWF cdsapi retrieval script to download the ERA5 data and the grib2arl FORTRAN tool to convert the .grb files to .arl files. Upon the last step, after downloadiing the surface and pressure level fields separately and combining them together using the CDO library, the grib2arl tool seems to crash on multiple test files. I'll try to break it down step by step:

1) I submit (and later download) surface and model level data from the ECWMF servers (script available upon request, could only upload 3 here).

2) Using the attached script "

process_multiple.py.txt: (925 Bytes) Downloaded 12229 times

", the .grb (test-)files are converted to .arl files using the grib2arl tool (which I believe was included in the data2arl directory of some HYSPLIT version, but is probably deprecated). I tested this for both 2021 and 2023 ERA5 meteo files.

3) After succesfully processing the first few files from both 2021 and 2023 sets of ERA5 data, grib2arl returns the error messages

grib2arl_error_2021.txt: (19.09 KiB) Downloaded 12171 times

and

grib2arl_error_2023.txt: (61.14 KiB) Downloaded 12151 times

.

It seems like this is an issue related to missing data (in the vertical levels) in the files 'ERA5-20210107' and 'ERA5-20230122.grb', as you can see from the following CFG.ARL prompts that are returned for the processing of these files:

ERA5-20210107 file:

Code: Select all

Model Type:         ECMG
Grid Numb:            99
Vert Coord:            2
Pole Lat:               72.000
Pole Lon:               35.000
Ref Lat:                 0.250
Ref Lon:                 0.250
Grid Size:               0.000
Orientation:             0.000
Cone Angle:              0.000
Sync X Pt:               1.000
Sync Y Pt:               1.000
Sync Lat:               33.000
Sync Lon:              345.000
Reserved:                0.000
Numb X pt:           201
Numb Y pt:           157
Numb Levels:          20
Level  0:           .00000  6 SHGT TPP6 U10M V10M T02M PBLH
Level  1:           ******  5 HGTS TEMP UWND VWND WWND
Level  2:           ******  5 HGTS TEMP UWND VWND WWND
Level  3:           ******  5 HGTS TEMP UWND VWND WWND
Level  4:           2628.2  5 HGTS TEMP UWND VWND WWND
Level  5:           2116.5  5 HGTS TEMP UWND VWND WWND
Level  6:           1000.0  6 HGTS TEMP UWND VWND WWND RELH
Level  7:           975.00  6 HGTS TEMP UWND VWND WWND RELH
Level  8:           950.00  6 HGTS TEMP UWND VWND WWND RELH
Level  9:           925.00  6 HGTS TEMP UWND VWND WWND RELH
Level 10:           900.00  6 HGTS TEMP UWND VWND WWND RELH
Level 11:           875.00  6 HGTS TEMP UWND VWND WWND RELH
Level 12:           850.00  6 HGTS TEMP UWND VWND WWND RELH
Level 13:           825.00  6 HGTS TEMP UWND VWND WWND RELH
Level 14:           800.00  6 HGTS TEMP UWND VWND WWND RELH
Level 15:           750.00  6 HGTS TEMP UWND VWND WWND RELH
Level 16:           700.00  6 HGTS TEMP UWND VWND WWND RELH
Level 17:           650.00  6 HGTS TEMP UWND VWND WWND RELH
Level 18:           500.00  6 HGTS TEMP UWND VWND WWND RELH
Level 19:           350.00  6 HGTS TEMP UWND VWND WWND RELH

ERA5-20230123 file:

Code: Select all

Model Type:         ECMG
Grid Numb:            99
Vert Coord:            2
Pole Lat:               72.000
Pole Lon:               35.000
Ref Lat:                 0.250
Ref Lon:                 0.250
Grid Size:               0.000
Orientation:             0.000
Cone Angle:              0.000
Sync X Pt:               1.000
Sync Y Pt:               1.000
Sync Lat:               33.000
Sync Lon:              345.000
Reserved:                0.000
Numb X pt:           201
Numb Y pt:           157
Numb Levels:          20
Level  0:           .00000  6 SHGT TPP6 U10M V10M T02M PBLH
Level  1:           ******  0
Level  2:           ******  0
Level  3:           ******  0
Level  4:           ******  0
Level  5:           ******  0
Level  6:           ******  0
Level  7:           ******  0
Level  8:           ******  0
Level  9:           ******  0
Level 10:           ******  0
Level 11:           ******  0
Level 12:           ******  0
Level 13:           ******  0
Level 14:           ******  0
Level 15:           ******  0
Level 16:           1000.0  6 HGTS TEMP UWND VWND WWND RELH
Level 17:           975.00  6 HGTS TEMP UWND VWND WWND RELH
Level 18:           950.00  6 HGTS TEMP UWND VWND WWND RELH
Level 19:           925.00  6 HGTS TEMP UWND VWND WWND RELH

I thought a possible solution might be to simply not include some of the vertical levels, but since grib2arl does not seem to crash on the same vertical level, this probably wouldn't help. Moreover, checking the .grb files using grib_dump shows that both of the aforementioned ERA5 files are filled with data over these vertical levels, it is just that grib2arl can't seem to access or process the data for some reason.

Does anyone have experience with the grib2arl tool and this kind of error?