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'ml2pl' to convert JRA hybrid levels to pressure levels

Added by Mireia Mateu almost 14 years ago

Hi all!

I'd like to convert my GRIB JRA (Japanese Re-analysis data)hybrid levels data to pressure levels and I've been reading other entries with similar problems so I have tried this:

$> cdo partab -chname,var1,aps 2008120100.grib >mypartab
$> cdo ml2pl,100000,95000,90000,85000,80000,75000,70000,65000,60000,55000,50000,45000,40000,35000,32500,30000,27500,25000,22500,20000,17500,15000,12500,10000,8500,7000,6000,5000,4000,3000,2000,1000,700,500,300,200,100,0 -setpartab,mypartab 2008120100.grib 2008120100pres.grib

But it doesn't work, it keeps saying:
'cdo ml2pl (Abort): Surface pressure not found!'

Any ideas?
Thanks

Mireia


Replies (4)

RE: 'ml2pl' to convert JRA hybrid levels to pressure levels - Added by Ralf Mueller almost 14 years ago

Would be good to have the input data for testing.

Regards
Ralf

RE: 'ml2pl' to convert JRA hybrid levels to pressure levels - Added by Uwe Schulzweida almost 14 years ago

Dear Mireia,

The CDO operator ml2pl supports only the WMO standard GRIB table number 2 and ECMWF local table number 128 to identify the variables surface pressure, temperature, and orography. For GRIB input files you have to work with GRIB table numbers and code numbers. The change of variable names is only suitable for netCDF input files.
You are using a GRIB file with variables defined for GRIB table number 3. The file contains variables with the code number 1, 8, 33, 34, and 11. You have to map these code numbers to the WMO standard GRIB table number 2 or ECMWF local table number 128. I don't know the meaning of your code numbers. Here is an example to map your code numbers to ECMWF local table number 128

129 orography
130 temperature
134 pressure
assuming 1 is the pressure, 8 is the orography and 11 is the temperature:
cdo ml2pl,100000,95000,...,100,0 -settabnum,128 -chcode,1,134,8,129,11,130 2008120100.grib 2008120100pres.grib

Regards,
Uwe

RE: 'ml2pl' to convert JRA hybrid levels to pressure levels - Added by Mireia Mateu almost 14 years ago

Dear Uwe,

I had tried with the 'chcode' but without the 'settabnum' and it didn't work, now it does!
Thanks a lot.

Regards,
Mireia

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