Opened 3 years ago
Closed 2 years ago
#2627 closed help (fixed)
netcdf valid_min and valid_max; pp conversion
Reported by: | ajd | Owned by: | um_support |
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Component: | UM Tools | Keywords: | |
Cc: | Platform: | ||
UM Version: |
Description
Hi CMS,
I've previously used either a convsh tcl script or iris to convert from pp files to netcdf, and found that occasionally the converted netcdfs are not consistent. Specifically, the convsh *tcl script adds the netcdf attributes valid_min and valid_max, which iris does not do. Depending on the language I use for my analysis, these attributes are sometimes used and sometimes ignored (e.g. NCL ignores those but python doesn't), which can lead to inconsistencies in the results. Is this a known 'problem' and do you know where the values for valid min and max come from?
Many thanks,
Andrea
Change History (2)
comment:1 Changed 3 years ago by jeff
comment:2 Changed 2 years ago by willie
- Resolution set to fixed
- Status changed from new to closed
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Hi Andrea
The valid_max and valid_min should be the max and min of the field, xconv/convsh will work this out from the field values.
I think python netcdf treats any values outside of valid_max and valid_min as missing data, this should not matter if you use the fields directly but could cause problems if you process the field and don't change the valid_max and valid_min values to match.
It is possible to turn these attributes off in convsh, add this line near the top of the script
Jeff.