Custom Query (124 matches)

Unidata has released a new version of the udunits package, which fixes some problems in the original version. Although the units supported are very largely the same, CF should specify which version is the reference standard, since there are a few differences. Unidata deprecates the original version. Therefore version 2 should be the CF reference. This ticket proposes to clarify and update the CF standard by

• Replacing all references to UDUNITS with UDUNITS-2.

• Replacing all references to udunits.dat with references to the appropriate xml file of UDUNITS-2.

I'm submitting this as a defect, because I don't think it materially affects the CF standard.

Jonathan Gregory

1. New cell_methods of range

2. Moderator

Alison Pamment

3. Requirement

Provide a way to indicate that the data value for an element of data variable is the range of values (the absolute difference between the maximum and the minimum) that occur within the cell.

4. Initial Statement of Technical Proposal

Add a entry in the table of Appendix E, as follows

The choice of the word range is consistent with the existing cell_methods of mid_range.

5. Benefits

The particular use case which motivated the proposal was provided by José María Rodríguez González, who wished to describe the diurnal range of surface air temperature. With the new convention, this could be described by cell_methods="time: range" with a time coordinate variable whose bounds specified daily intervals. This new use of cell_methods corresponds to the use of maximum and minimum to describe the daily maximum and daily minimum temperature.

6. Status Quo

Using the long_name is the most likely alternative.

In section 3.1 of the conformance document, I propose that the item

The units of a variable that specifies a standard_name must be consistent with the units given in the standard name table. The units must also be consistent with a specified cell_methods attribute, if one is present.

should be modified to read

The units of a variable that specifies a standard_name must be consistent with the units given in the standard name table and with the standard_name modifier, if there is one. The units must also be consistent with a specified cell_methods attribute, if one is present.

That will make it consistent with section 3.3 of the CF standard.