Hi Karl,
I'm glad you think the first example makes sense - it's the one that
makes most sense to me too! But I'm wondering if one *must* store
ap(z)/p0+b(z) (or a(k)+b(k) if that's the parameterisation in use), or
if one could store something else and still be a valid CF file?
The second example is trying to do two things:
1. Demonstrate one possible example of storing "something else". In
this case it's storing "b" in the "z" variable, as shown by the "b: z"
entry in the formula terms. (As an aside, I'd find formula terms a whole
lot more readable if it allowed commas! e.g. "ap: delta, b: z, ps:
surface_pressure" instead of just "ap: delta b: z ps: surface_pressure".
There, I've got it off my chest.)
2. Determine whether this is what one *must* store. I strongly
suspect/hope not, but would love to know for sure.
Richard Hattersley AVD Iris Technical Lead
Met Office FitzRoy Road Exeter Devon EX1 3PB United Kingdom
Tel: +44 (0)1392 885702 Fax: +44 (0)1392 885681
Email: richard.hattersley at metoffice.gov.uk
<mailto:richard.hattersley at metoffice.gov.uk> Website:
www.metoffice.gov.uk <
http://www.metoffice.gov.uk/>
________________________________
From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On
Behalf Of Karl Taylor
Sent: 16 August 2012 17:10
To: cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] Dimensionless vertical coordinate
values
Hi Richard,
In your example, I think it would be o.k. to define z(z) as your
vertical coordinate variable (your first example). You would then
store in z(z) the values of ap(z)/p0+b(z), which is the vertical
coordinate as defined in appendix D of the conventions document.
I don't think your second example makes sense ... are you
storing b in z or ap in z??
I hope someone else will confirm this because I'm not absolutely
positive.
Best regards,
Karl
On 8/16/12 5:04 AM, Hattersley, Richard wrote:
Hi all,
What does the standard name of a dimensionless vertical
coordinate imply about the meaning of the numeric values of that
coordinate?
For example, if a coordinate variable has a standard
name of "atmosphere_hybrid_sigma_pressure_coordinate" does that imply it
must contain values for either a(k)+b(k) or ap(k)/p0+b(k)?
float z(z) ;
z:standard_name =
"atmosphere_hybrid_sigma_pressure_coordinate" ;
z:long_name = "(delta / p0) + sigma" ;
z:units = "1" ;
z:formula_terms = "ap: delta b: sigma
ps: surface_pressure" ;
z:positive = "down" ;
float delta(z) ;
delta:units = "Pa" ;
float sigma(z) ;
sigma:units = "1" ;
float surface_pressure(y, x) ;
surface_pressure:units = "Pa" ;
Or to put it another way, if it just contained values
for ap(k) and appeared in its own list of formula terms would that be
invalid?
float z(z) ;
z:standard_name =
"atmosphere_hybrid_sigma_pressure_coordinate" ;
z:units = "1" ;
z:formula_terms = "ap: delta b: z ps:
surface_pressure" ;
z:positive = "down" ;
float delta(z) ;
delta:units = "Pa" ;
float surface_pressure(y, x) ;
surface_pressure:units = "Pa" ;
Richard Hattersley AVD Iris Technical Lead
Met Office FitzRoy Road Exeter Devon EX1 3PB United
Kingdom
Tel: +44 (0)1392 885702 Fax: +44 (0)1392 885681
Email: richard.hattersley at metoffice.gov.uk
<mailto:richard.hattersley at metoffice.gov.uk> Website:
www.metoffice.gov.uk <
http://www.metoffice.gov.uk>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/attachments/20120820/6d9e09c0/attachment-0001.html>
Received on Mon Aug 20 2012 - 10:05:52 BST
