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Each variable in a history output file from an E3SM component should have AT LEAST the following attributes if defined for the variable. Others may be added as needed by the model.
The missing value or FillValue should be the CMIP standard 1.e+20.
units = (CF-compliant unit if available. See https://cfconventions.org/Data/cf-standard-names/current/build/cf-standard-name-table.html. NOTE a unitless variable should either have no “units” attribute OR the unit should be set to “1”)
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