Missing values encountered in interpolated fields when running metgrid with UCAR ERA5 Data

[fcarotenuto]

Dear all,

I'm (desperately) try to run WRF with the ERA5 data available from UCAR through the era5_to_int Python script.
Through extensive research and trial and error I think I've understood the variables needed to run WRF with the --isobaric option of era5_to_int which are the following:

- Dataset "d633000". On pressure levels (mbar): Z/Q/T/U/V
- Dataset "d633000". Surface variables: SOILGEO/MSL/VAR_2T/VAR_2D/VAR_10U/VAR_10V/RSN/SD/SSTK/SKT/SWVL1/SWVL2/SWVL3/SWVL4/STL1/STL2/STL3/STL4/CI
- Dataset "d633006". On model levels: SP
- Invariants: LSM (d633000, 1979/01/01 00:00 - 1979/01/01 00:00), Z (d633006, 2016/01/01 00:00 - 2016/01/01 00:00)

This set of variables allows era5_to_int to run as era5_to_int.py -i -p /home/wrf/Software/Data/ERA5 2023-07-01_00 2023-07-15_23 1 &> era5_to_int.out and produce a complete set of "ERA5:" data (see era5_to_int.out.txt attached).

Still, If I try to run metgrid.exe it complaints about encountering missing values in interpolated fields (PRES, SOILHGT, PSFC, PMSL, GHT) and does not run (see attached metgrid.out.txt and metgrid.log).

The things that I've tried to do up until now were:

1) Increase the domain over which ERA5 data were subsetted, to be sure that my WRF domain was more than fully included. Error is the same.

2) Use model levels data instead than isobaric ones. No matter how I do the request it downloads only the "Q" data and even if the request is from 00:00 of 2023/07/01 the first file is 2023/07/01 06. Thus era5_to_int complains on missing 2023/07/01 00.

Any help would be super appreciated

Thanks!

 

[Ming Chen]

I just run a test case using era5_to_int.py to create intermediate files. All work fine and my case can run through WPS to WRF.

Would you please upload your namelist.wps for me to take a look?

Also, please tell me what files you download from NCAR RDA and your command usage.

Thanks.

 

[fcarotenuto]

Dear Ming Chen,

Thank you for your reply!

In attachment I've put:
1. my namelist.wps
2. the list of files I've downloaded from NCAR RDA
3. the ipynb I use to obtain said files

The command I use is:
era5_to_int.py -i -p /path/to/files 2023-07-01_00 2023-07-15_23 1 &> era5_to_int.out

When I run it for model levels files I remove "-i" from the command.

Thank you again for your support!

 

[Ming Chen]

I just noticed that you didn't download global ERA5 data? Please let me know if I am wrong.

Note that some of the data are on Gaussian grids, and our script can only handle global data.

Please download the entire ERA5 data on global grids and rerun the case. Let me know if you still have issues.

 

[William Oswaldo]

Subject: Issues running era5_to_int.py with ERA5 pressure-level and surface data only — unclear behavior


Dear Ming Chen and team,


Thank you for your support and time.


We are experiencing several issues trying to use the era5_to_int.py script with ERA5 data from NCAR RDA (d633.0). We have not applied any spatial subsetting — the data are global.


We have prepared two sets of data:

1. Pressure-level (pl) variables (37 levels):​

Path: /home/nodo2/Descarga/ERA5/pl/201301/01/


We downloaded the following variables:

• Z (129)
• T (130)
• U (131)
• V (132)
• Q (133)
• R (157)

These are standard 37 pressure levels.

2. Surface and invariant variables:​

Path: /home/nodo2/Descarga/ERA5/sfc/201301/


We downloaded:

2t, 2d, 10u, 10v, sp, msl, skt,
stl1, stl2, stl3, stl4,
swvl2, swvl3, swvl4,
ci, sd,
z (invariant), lsm (invariant)

File examples:

/e5.oper.an.sfc.128_167_2t.ll025sc.2013010100_2013013123.nc
/e5.oper.invariant.128_129_z.ll025sc.1979010100_1979010100.nc
/e5.oper.invariant.128_172_lsm.ll025sc.1979010100_1979010100.nc

We tried different commands, like this command:

python era5_to_int.py --path /home/nodo2/Descarga/ERA5/sfc/201301 \
-v "2t 2d 10u 10v sp msl skt stl1 stl2 stl3 stl4 swvl2 swvl3 swvl4 ci sd z lsm" \
2013-01-01_00 2013-01-01_18
Error: 2t 2d 10u 10v sp msl skt stl1 stl2 stl3 stl4 swvl2 swvl3 swvl4 ci sd z lsm is not a known WPS variable

python era5_to_int.py --path /home/nodo2/Descarga/ERA5/sfc/201301 \
-v "TT DEWPT UU VV PSFC PMSL SKINTEMP ST000007 ST007028 ST028100 ST100289 SM007028 SM028100 SM100289 SEAICE SNOW_EC LANDSEA" \
2013-01-01_00 2013-01-01_18
Missing data file: q from model levels

and the normal situation for the variables using -i:

python era5_to_int.py --path /home/nodo2/Descarga/ERA5/sfc/201301 -i 2013-01-01_00 2013-01-01_18
datetime = 2013-01-01 00:00:00
until_datetime = 2013-01-01 18:00:00
interval_hours = 6:00:00
Processing time record 2013-01-01_00
Error: Could not find file e5.oper.an.pl.128_129_z.ll025sc.2013010100_2013010123.nc needed for ERA5 variable Z


python era5_to_int.py --path /home/nodo2/Descarga/ERA5/pl/201301/01 -i 2013-01-01_00 2013-01-01_18
datetime = 2013-01-01 00:00:00
until_datetime = 2013-01-01 18:00:00
interval_hours = 6:00:00
Processing time record 2013-01-01_00
Traceback (most recent call last):
File "/home/nodo2/Convertir_NC_GRIB_WPS/era5_to_int/era5_to_int.py", line 579, in <module>
idx = find_time_index(e5filename, initdate)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/nodo2/Convertir_NC_GRIB_WPS/era5_to_int/era5_to_int.py", line 387, in find_time_index
with Dataset(ncfilename) as f:
^^^^^^^^^^^^^^^^^^^
File "src/netCDF4/_netCDF4.pyx", line 2521, in netCDF4._netCDF4.Dataset.__init__
File "src/netCDF4/_netCDF4.pyx", line 2158, in netCDF4._netCDF4._ensure_nc_success
OSError: [Errno -101] NetCDF: HDF error: '/home/nodo2/Descarga/ERA5/pl/201301/01/e5.oper.an.pl.128_129_z.ll025sc.2013010100_2013010123.nc'


All we have is error.

This is confusing, because we are not using any model-level (ml) data, and we have already downloaded q at pressure levels (pl).

1. Why does era5_to_int.py expect model-level data when we are working in isobaric mode (-i)? Even though q is present in pl files, the script looks for it in ml.
2. Is there a way to explicitly disable ml dependencies, or a flag to only process pl and/or sfc?
3. Can we use only surface data (e.g. for sea surface temperature, 2m air temp, 10m winds)? The script seems to reject all -v variable names even when using the WPS-compliant internal ones.

Any guidance or clarification would be deeply appreciated. We'd like to use this tool for a case study using only pressure-level and surface data.


Best regards,

William Oswaldo Riaño Acosta

 

[Ming Chen]

I am sorry to answer late but this is because I have been on a business trip recently. Please see my answers below:

Subject: Issues running era5_to_int.py with ERA5 pressure-level and surface data only — unclear behavior


Dear Ming Chen and team,


Thank you for your support and time.


We are experiencing several issues trying to use the era5_to_int.py script with ERA5 data from NCAR RDA (d633.0). We have not applied any spatial subsetting — the data are global.


We have prepared two sets of data:

1. Pressure-level (pl) variables (37 levels):​

Path: /home/nodo2/Descarga/ERA5/pl/201301/01/


We downloaded the following variables:

• Z (129)
• T (130)
• U (131)
• V (132)
• Q (133)
• R (157)

These are standard 37 pressure levels.

These are the variables required by WPS. It is correct that you downlaod these data.

2. Surface and invariant variables:​

Path: /home/nodo2/Descarga/ERA5/sfc/201301/


We downloaded:

2t, 2d, 10u, 10v, sp, msl, skt,
stl1, stl2, stl3, stl4,
swvl2, swvl3, swvl4,
ci, sd,
z (invariant), lsm (invariant)

These are surface variables required.

File examples:

/e5.oper.an.sfc.128_167_2t.ll025sc.2013010100_2013013123.nc
/e5.oper.invariant.128_129_z.ll025sc.1979010100_1979010100.nc
/e5.oper.invariant.128_172_lsm.ll025sc.1979010100_1979010100.nc

We tried different commands, like this command:

python era5_to_int.py --path /home/nodo2/Descarga/ERA5/sfc/201301 \
-v "2t 2d 10u 10v sp msl skt stl1 stl2 stl3 stl4 swvl2 swvl3 swvl4 ci sd z lsm" \
2013-01-01_00 2013-01-01_18
Error: 2t 2d 10u 10v sp msl skt stl1 stl2 stl3 stl4 swvl2 swvl3 swvl4 ci sd z lsm is not a known WPS variabl\
-v "TT DEWPT UU VV PSFC PMSL SKINTEMP ST000007 ST007028 ST028100 ST100289 SM007028 SM028100 SM100289 SEAICE SNOW_EC LANDSEA" \
2013-01-01_00 2013-01-01_18
Missing data file: q from model levels

and the normal situation for the variables using -i:

python era5_to_int.py --path /home/nodo2/Descarga/ERA5/sfc/201301 -i 2013-01-01_00 2013-01-01_18
datetime = 2013-01-01 00:00:00
until_datetime = 2013-01-01 18:00:00
interval_hours = 6:00:00
Processing time record 2013-01-01_00
Error: Could not find file e5.oper.an.pl.128_129_z.ll025sc.2013010100_2013010123.nc needed for ERA5 variable Z


python era5_to_int.py --path /home/nodo2/Descarga/ERA5/pl/201301/01 -i 2013-01-01_00 2013-01-01_18
datetime = 2013-01-01 00:00:00
until_datetime = 2013-01-01 18:00:00
interval_hours = 6:00:00
Processing time record 2013-01-01_00
Traceback (most recent call last):
File "/home/nodo2/Convertir_NC_GRIB_WPS/era5_to_int/era5_to_int.py", line 579, in <module>
idx = find_time_index(e5filename, initdate)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/nodo2/Convertir_NC_GRIB_WPS/era5_to_int/era5_to_int.py", line 387, in find_time_index
with Dataset(ncfilename) as f:
^^^^^^^^^^^^^^^^^^^
File "src/netCDF4/_netCDF4.pyx", line 2521, in netCDF4._netCDF4.Dataset.__init__
File "src/netCDF4/_netCDF4.pyx", line 2158, in netCDF4._netCDF4._ensure_nc_success
OSError: [Errno -101] NetCDF: HDF error: '/home/nodo2/Descarga/ERA5/pl/201301/01/e5.oper.an.pl.128_129_z.ll025sc.2013010100_2013010123.nc'

Please simply issue the command:

python era5_to_int.py --path /home/nodo2/Descarga/ERA5/sfc/201301 -i start_date ime end datetime interval_hours

I expect this command should create correct intermediate files.

All we have is error.

This is confusing, because we are not using any model-level (ml) data, and we have already downloaded q at pressure levels (pl).

1. Why does era5_to_int.py expect model-level data when we are working in isobaric mode (-i)? Even though q is present in pl files, the script looks for it in ml.

the option '-i' tells the script to process pressure level data. Without this command line option, the default is to process model level data

1. Is there a way to explicitly disable ml dependencies, or a flag to only process pl and/or sfc?

Please see the usage below:
era5_to_int.py [-h] [-p PATH] [-i] [-v VARIABLES] datetime [until_datetime] [interval_hours]

positional arguments:
datetime the date-time to convert in YYYY-MM-DD_HH format
until_datetime the date-time in YYYY-MM-DD_HH format until which records are converted (Default:
datetime)
interval_hours the interval in hours between records to be converted (Default: 6)

options:
-h, --help show this help message and exit
-p PATH, --path PATH the local path to search for ERA5 netCDF files
-i, --isobaric use ERA5 pressure-level data rather than model-level data
-v VARIABLES, --variables VARIABLES
a comma-separated list, without spaces, of WPS variable names to process

1. Can we use only surface data (e.g. for sea surface temperature, 2m air temp, 10m winds)? The script seems to reject all -v variable names even when using the WPS-compliant internal ones.

Any guidance or clarification would be deeply appreciated. We'd like to use this tool for a case study using only pressure-level and surface data.

Please see the example below:
era5_to_int.py -v LANDSEA,SEAICE,SKINTEMP 2024-01-01_00 2024-01-31_00 24

Note that the variable names are names in WPS, not the names in original ERA5 data.

Best regards,

William Oswaldo Riaño Acosta

Please let me know if you have more questions.

 

[William Oswaldo]

Subject: era5_to_int.py still requesting model-level data despite --isobaric flag


Dear Ming,


Thank you again for your support.


Following your guidance, I made good progress using era5_to_int.py. Specifically:

• I organized all ERA5 files under /home/nodo2/Descarga/ERA5/, ensuring both pressure-level (pl) and surface-level (sfc) files are placed in the same main folder, as I understood this is necessary for the script to locate all required inputs.
• I verified that all the relevant .nc files are present and valid using ncdump -h.
• I also downloaded additional surface variables that the script required (e.g., STLx, SWVLx, SKT, CI, etc.).

Then, I ran the script with:


python era5_to_int.py --path /home/nodo2/Descarga/ERA5 -i 2013-01-01_00 2013-01-01_18


The script began processing variables correctly, including TT, DEWPT, UU, VV, SMxxx, STxxx, SEAICE, SKINTEMP, etc. However, I later encountered this error:




Error: Could not find file e5.oper.an.ml.128_134_sp.regn320sc.2013010100_2013010105.nc needed for ERA5 variable SP


This is confusing, because:

• I’m running with -i (isobaric mode),
• I already have SP in the surface file:
  /home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_134_sp.ll025sc.2013010100_2013013123.nc

So my questions are:

1. Is the script supposed to look for SP in model-level (ml) files even when running in isobaric mode?
2. Is there a way to force the script to use only pl and sfc data, ignoring ml dependencies?
3. Could this be solved by modifying the code to allow SP to be read from the surface file directly?

Here’s a snippet of the log:


...
Converting PMSL at 2013-01-01_00:00:00
Error: Could not find file e5.oper.an.ml.128_134_sp.regn320sc.2013010100_2013010105.nc needed for ERA5 variable SP


Any clarification would be greatly appreciated, as we are trying to run a test case relying only on pressure-level and surface data.

and this is the process of the script:

datetime = 2013-01-01 00:00:00
until_datetime = 2013-01-01 18:00:00
interval_hours = 6:00:00
Processing time record 2013-01-01_00
/home/nodo2/Descarga/ERA5/e5.oper.an.pl.128_129_z.ll025sc.2013010100_2013010123.nc
Converting GEOPT at 2013-01-01_00:00:00
GEOPT is NOT being written to the intermediate file at level 100.0
Computing GHT at 100.0
GEOPT is NOT being written to the intermediate file at level 200.0
Computing GHT at 200.0
GEOPT is NOT being written to the intermediate file at level 300.0
Computing GHT at 300.0
GEOPT is NOT being written to the intermediate file at level 500.0
Computing GHT at 500.0
GEOPT is NOT being written to the intermediate file at level 700.0
Computing GHT at 700.0
GEOPT is NOT being written to the intermediate file at level 1000.0
Computing GHT at 1000.0
GEOPT is NOT being written to the intermediate file at level 2000.0
Computing GHT at 2000.0
GEOPT is NOT being written to the intermediate file at level 3000.0
Computing GHT at 3000.0
GEOPT is NOT being written to the intermediate file at level 5000.0
Computing GHT at 5000.0
GEOPT is NOT being written to the intermediate file at level 7000.0
Computing GHT at 7000.0
GEOPT is NOT being written to the intermediate file at level 10000.0
Computing GHT at 10000.0
GEOPT is NOT being written to the intermediate file at level 12500.0
Computing GHT at 12500.0
GEOPT is NOT being written to the intermediate file at level 15000.0
Computing GHT at 15000.0
GEOPT is NOT being written to the intermediate file at level 17500.0
Computing GHT at 17500.0
GEOPT is NOT being written to the intermediate file at level 20000.0
Computing GHT at 20000.0
GEOPT is NOT being written to the intermediate file at level 22500.0
Computing GHT at 22500.0
GEOPT is NOT being written to the intermediate file at level 25000.0
Computing GHT at 25000.0
GEOPT is NOT being written to the intermediate file at level 30000.0
Computing GHT at 30000.0
GEOPT is NOT being written to the intermediate file at level 35000.0
Computing GHT at 35000.0
GEOPT is NOT being written to the intermediate file at level 40000.0
Computing GHT at 40000.0
GEOPT is NOT being written to the intermediate file at level 45000.0
Computing GHT at 45000.0
GEOPT is NOT being written to the intermediate file at level 50000.0
Computing GHT at 50000.0
GEOPT is NOT being written to the intermediate file at level 55000.0
Computing GHT at 55000.0
GEOPT is NOT being written to the intermediate file at level 60000.0
Computing GHT at 60000.0
GEOPT is NOT being written to the intermediate file at level 65000.0
Computing GHT at 65000.0
GEOPT is NOT being written to the intermediate file at level 70000.0
Computing GHT at 70000.0
GEOPT is NOT being written to the intermediate file at level 75000.0
Computing GHT at 75000.0
GEOPT is NOT being written to the intermediate file at level 77500.0
Computing GHT at 77500.0
GEOPT is NOT being written to the intermediate file at level 80000.0
Computing GHT at 80000.0
GEOPT is NOT being written to the intermediate file at level 82500.0
Computing GHT at 82500.0
GEOPT is NOT being written to the intermediate file at level 85000.0
Computing GHT at 85000.0
GEOPT is NOT being written to the intermediate file at level 87500.0
Computing GHT at 87500.0
GEOPT is NOT being written to the intermediate file at level 90000.0
Computing GHT at 90000.0
GEOPT is NOT being written to the intermediate file at level 92500.0
Computing GHT at 92500.0
GEOPT is NOT being written to the intermediate file at level 95000.0
Computing GHT at 95000.0
GEOPT is NOT being written to the intermediate file at level 97500.0
Computing GHT at 97500.0
GEOPT is NOT being written to the intermediate file at level 100000.0
Computing GHT at 100000.0
/home/nodo2/Descarga/ERA5/e5.oper.an.pl.128_133_q.ll025sc.2013010100_2013010123.nc
Converting SPECHUMD at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.pl.128_130_t.ll025sc.2013010100_2013010123.nc
Converting TT at 2013-01-01_00:00:00
Computing RH at 100.0
Computing RH at 200.0
Computing RH at 300.0
Computing RH at 500.0
Computing RH at 700.0
Computing RH at 1000.0
Computing RH at 2000.0
Computing RH at 3000.0
Computing RH at 5000.0
Computing RH at 7000.0
Computing RH at 10000.0
Computing RH at 12500.0
Computing RH at 15000.0
Computing RH at 17500.0
Computing RH at 20000.0
Computing RH at 22500.0
Computing RH at 25000.0
Computing RH at 30000.0
Computing RH at 35000.0
Computing RH at 40000.0
Computing RH at 45000.0
Computing RH at 50000.0
Computing RH at 55000.0
Computing RH at 60000.0
Computing RH at 65000.0
Computing RH at 70000.0
Computing RH at 75000.0
Computing RH at 77500.0
Computing RH at 80000.0
Computing RH at 82500.0
Computing RH at 85000.0
Computing RH at 87500.0
Computing RH at 90000.0
Computing RH at 92500.0
Computing RH at 95000.0
Computing RH at 97500.0
Computing RH at 100000.0
/home/nodo2/Descarga/ERA5/e5.oper.an.pl.128_131_u.ll025uv.2013010100_2013010123.nc
Converting UU at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.pl.128_132_v.ll025uv.2013010100_2013010123.nc
Converting VV at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.invariant.128_172_lsm.ll025sc.1979010100_1979010100.nc
Converting LANDSEA at 1979-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_034_sstk.ll025sc.2013010100_2013013123.nc
Converting SST at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_235_skt.ll025sc.2013010100_2013013123.nc
Converting SKINTEMP at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_039_swvl1.ll025sc.2013010100_2013013123.nc
Converting SM000007 at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_040_swvl2.ll025sc.2013010100_2013013123.nc
Converting SM007028 at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_041_swvl3.ll025sc.2013010100_2013013123.nc
Converting SM028100 at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_042_swvl4.ll025sc.2013010100_2013013123.nc
Converting SM100289 at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_139_stl1.ll025sc.2013010100_2013013123.nc
Converting ST000007 at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_170_stl2.ll025sc.2013010100_2013013123.nc
Converting ST007028 at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_183_stl3.ll025sc.2013010100_2013013123.nc
Converting ST028100 at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_236_stl4.ll025sc.2013010100_2013013123.nc
Converting ST100289 at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_031_ci.ll025sc.2013010100_2013013123.nc
Converting SEAICE at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_167_2t.ll025sc.2013010100_2013013123.nc
Converting TT at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_168_2d.ll025sc.2013010100_2013013123.nc
Converting DEWPT at 2013-01-01_00:00:00
DEWPT is NOT being written to the intermediate file at level 200100.0
Computing RH at 200100.0
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_165_10u.ll025sc.2013010100_2013013123.nc
Converting UU at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_166_10v.ll025sc.2013010100_2013013123.nc
Converting VV at 2013-01-01_00:00:00
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_033_rsn.ll025sc.2013010100_2013013123.nc
Converting SNOW_DEN at 2013-01-01_00:00:00
SNOW_DEN is NOT being written to the intermediate file at level 200100.0
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_141_sd.ll025sc.2013010100_2013013123.nc
Converting SNOW_EC at 2013-01-01_00:00:00
SNOW_EC is NOT being written to the intermediate file at level 200100.0
Computing SNOWH and SNOW
/home/nodo2/Descarga/ERA5/e5.oper.an.sfc.128_151_msl.ll025sc.2013010100_2013013123.nc
Converting PMSL at 2013-01-01_00:00:00
Error: Could not find file e5.oper.an.ml.128_134_sp.regn320sc.2013010100_2013010105.nc needed for ERA5 variable SP



Best regards,
William Oswaldo Riaño Acosta

 

[Ming Chen]

Hi,
The message below clearly indicates that you don't have the datafile required as input.
Error: Could not find file e5.oper.an.ml.128_134_sp.regn320sc.2013010100_2013010105.nc needed for ERA5 variable SP

SP datafile can be found in NCAR RDA Dataset d633000, where you can find the link on the left (i/e/. ERA5 atmospheric surface analysis [netCDF4]), click this link and you will find all datafiles that contain SP.

Please download the files and rerun the script. Let me know if you still have some issues.