[CF-metadata] domain for calendar, add_offset, scale_factor

From: Benno Blumenthal <benno>
Date: Tue, 02 Oct 2007 14:25:30 -0400

Jonathan Gregory wrote:
>> 1) I was not aware that it was illegal to scale a coordinate variable
>> using add_offset and scale_factor.
>>
>
> It has not been envisaged that there was a need for it, as far as I remember.
> Coord vars usually take a small amount of space, relative to data vars, so
> don't need to be compressed. In principle I don't see why it shouldn't be
> allowed, as they would still satisfy requirements of being monotonic and not
> having missing data. Do you have a need for it?
>
On occasion we use it for time for time series with many points:
putting a large offset into add_offset so that time can be single
precision and still be meaningful. Obviously double-precision time is
an alternative, as is changing the offset in the units. Bottom line is
that we (IRI aka Ingrid) have always supported add_offset and
scale_factor for both Coordinate and Non-Coordinate variables, and it
had not occurred to me that we were doing something unusual.

Benno
Received on Tue Oct 02 2007 - 12:25:30 BST