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Problems using a different SST dataset


New member
I want to use the OI SST dataset with ERA5 atmospheric data, using a single SST timestep to initialise. I have created an intermediate SST file using the pywinter package. It also seems that I should include the OI lands mask and include within the intermediate file, which I have done.
I have removed SST from the ECMWF Vtable and altered METGRID.TBL entry for SST to use the new OI lands mask. However, when I run metered an error is returned, relating to the lands mask. I have been trying numerous ways of doing this and not succeeding. I feel that using different SST data as an invariant would be a fairly common task. Is there any documentation for this, (the online tutorial case doesn't address the issue). I attach screenshots of the METGRID.TBL entry for SST, the output from inspection of the SST intermediate file and the error message. (The whole thing works if I just stick to using ERA5 data, including SST)


  • intermediate_file_inspection.png
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  • error_message.png
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  • SST_in_METGRID.TBL.png
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Is the OI SST data you're using a global field, or are you using a subset of the field. I ask because the error message is
Field IO_LNDSEA has missing values at level 201300 at (i, j) = (1, 1)

Sometimes when it's missing the values in the corner of the domain, it can mean the namelist domain covers more area than the available data. Otherwise, my concern is that the intermediate file output shows the SST field at level 201300, and I *think* it should be level 200100.
Thankyou. The filed is a subset, but it is larger than the domain required. You are right that the level is wrong. I created the intermediate file with pywinter which seems to set SST at the wrong level and I can't see a way around this.
I have decided to adopt a different approach. I am using python cfgrib to convert the OI netcdf files to grib. I then decided to interpolate the OI SST to the ERA5 grid prior to conversion, so that the ERA5 and OI data would be entirely compatible.
However, when running ungrib on the new SSTdata I get an error. The ERA5 data is hourly whereas OI SST data is daily, but I didn't think this was a problem as the online tutorial indicates that the time steps are interpolated by ungrib. However, this does not appear to be the case here.


  • ungrib_error_with_SST.png
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If you are running ungrib for daily SST data, make sure to set the interal_seconds to reflect that in the namelist.wps file. Then when you run metgrid, you'll set it back to the hourly interval.