Hi Jonathan et al,
This has reminded me of a CF units question that I was cogitating over a
few weeks back.
In Section 3.3 of the CF conventions it states that: "Unless it is
dimensionless, a variable with a standard_name attribute must have units
which are physically equivalent (not necessarily identical) to the
canonical units..."
As a non-physicist, would someone care to explain what determines when a
given pair of units are "physically equivalent", and when not. Some
examples would be great!
I can surmise that degrees K and degrees C are physically equivalent
(simple offset). But what about K and degrees Fahrenheit? If these, say,
are not physically equivalent then presumably you could not use the
latter as the units for "air_temperature". Right?
Regards,
Phil
On Tue, 2008-11-18 at 14:22 +0000, Jonathan Gregory wrote:
> Dear Roy et al
>
> > Were you saying that um m-3 is dimensionally equivalent to kg m-3 or have I misunderstood? To me changing between these units changes the Standard Name.
>
> Yes, sorry. That was a mistake. I meant to say ug m-3 and kg m-3 are
> dimensionally equivalent so equally acceptable. As you say, quantities with
> dimensionally different units have different standard names.
>
> Cheers
>
> Jonathan
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Received on Thu Nov 20 2008 - 09:12:35 GMT
