Custom Query (124 matches)

Example 7.4 in the conventions doc has an unlimited time dimension which must be listed as the first dimension in C ordering. The variables pressure, maxtemp, and ppn all have dimensions (station,time). All three should be modified to read (time,station).

I suggest that for readability and for consistency in the syntax of the definitions of dimensionless vertical coordinates, the following changes be made in the CF documentation.

1. Where the coordinate definition involves a construction like "for k<=k_c .... for k>k_c ....", follow each "for" phrase with a colon. [This is currently done inconsistently.]

2. Where the coordinate definition involves a term that is subsequently defined (e.g., the C(k) in the ocean-S coordinate), precede the definition of the term with "where".

These make the definitions easier to read. Note that CF does not mandate storage of the coordinate definitions in the netCDF files, but for CMIP, we store the formulas as a text string attribute attached to the coordinate variable and named "formula".

Section 2.5.1 of the convention defines the standard for the _FillValue attribute stating that it is "a scalar attribute and must have the same type as its variable." There are no specific exclusions, but I think that allowing the value NaN isn't a good idea.

The NetCDF standard doesn't prohibit the use of NaN as a _FillValue, but I did find several recommendations not to use NaN. The problem with allowing NaN is that any calculation or comparisons with NaN will return false.

I suggest a modification to the convention to recommend against the use of NaN as a _FillValue value.

Thoughts?