Dear Paul,
I'm not sure you can use a numeral in front of a unit. Also "yr" must
be used with caution since the length of a calendar year is not constant
(e.g., leap years). There is a discussion of this in section 4.4 of
the standard.
The only accepted standard names can be found on the CF website. I'm
not sure "linear", "change" and "1960-2008" are part of any standard
names. I would use "longname" to store a description like the one you
tried to put in standard_name (but I'd remove the underscores).
I hope someone else can expand on how trends should be stored in CF.
best regards,
Karl
On 7/8/10 9:44 PM, Paul.Durack at csiro.au wrote:
> Hi there folks..
>
> I'm trying to generate a file containing linear trends over specified periods (nominally 1960-2008) which are scaled to represent a linear trend for 50 years.
>
> A first crack at this file, and a corresponding header dump can be found at:
> http://*www.*marine.csiro.au/~dur041/100709_LinearChange.txt
>
> I'm a little confused how best to represent this, as I'm uncertain how to correctly create a simple climatology (mean values over a specified period) and the associated time dimension/attribute, let alone their perturbation fields, honouring the CF-1.4 conventions.
>
> I have generated such a file and run this against the CF-1.4 compliance checker, and aside from some general errors regarding syntax of standard_name attributes, have hit some troubles with units etc.. In particular, the changes represent units: degree_C/50Yrs, however this is not a valid unit in CF-1.4:
> ------------------
> Checking variable: thetao_change
> ------------------
> ERROR (3.3): Invalid syntax for 'standard_name' attribute: 'linear_potential_temperature_change_1960-2008'
> ERROR (3.1): Invalid units: degree_C/50Yrs
>
>
> The standard_name attributes indicate a simple syntax issue (I'm using a "-" value to represent the time period over which the linear trend is calculated):
> ------------------
> Checking variable: soi
> ------------------
> ERROR (3.3): Invalid syntax for 'standard_name' attribute: 'southern_oscillation_index_regression_1960-2008'
>
> I wonder if there is another variable attribute that I should set which expresses the years over which the regression was undertaken, and remove the "1960-2008" from the standard_name.
>
>
> I'd appreciate some pointers how to best create this file, best conforming with CF-1.4.
>
> Cheers,
>
> Paul
>
> *************************************
> Paul J. Durack
> PhD Candidate (CSIRO/UTas - QMS)
> CSIRO Marine and Atmospheric Research
> GPO Box 1538
> Hobart TAS 7001
> Telephone: +61 (3) 6232 5283
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> Email: Paul.Durack at csiro.au
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Received on Fri Jul 09 2010 - 10:35:07 BST
