[CF-metadata] Overlapping vertical bounds

Ansley C. Manke ansley.b.manke at noaa.gov
Mon Mar 6 11:19:53 MST 2017


Hi Evan,
Another couple of comments on using a file with overlapping bounds in 
Ferret.  Ferret does not have any grid operations that handle such 
bounds, but you can make use of the bounds as a variable in your Ferret 
session.  The full message:

    yes? use file.nc
    *** NOTE: Axis definition error on axis: ZAX. Bounds describe cells
    that overlap one another
      *** NOTE: Error in bounds "ZAX_bnds" or bounds do not enclose
    point on axis ZAX
      *** NOTE: Substituting coordinate midpoints

    yes? list/k=1:5 z[gz=var]
    yes? list/k=1:5 ZAX_bnds

The bounds are available in this 2-by-K variable, and you could make use 
of it in expressions that you define.

-Ansley

On 3/3/2017 3:59 PM, Ansley C. Manke wrote:
>
> Hi Evan,
>
> The data model in Ferret does not allow for overlapping bounds, nor 
> does it allow non-contiguous bounds.  Those are legal in CF, but 
> Ferret (as I imagine is the case for most software), does not 
> implement everything in the standard.
>
> In fact Ferret will not make use of your bounds definition; I believe 
> it will have ignored the bounds and will instead have defined the 
> grid-cell edges using the midpoints between axes. Use the command,
>
>    show axis/z axis_name
>
> to see what Ferret has done to set up its the internal representation 
> of the axis.
>
> -Ansley
>
>
> On 3/3/2017 7:32 AM, Manning, Evan M (398B) wrote:
>>
>> When I was researching  the topic I came across this:
>>
>> >/When I try and load the file using Ferret, this throws a warning.. 
>> Which/
>>
>> >/makes me think I¹m not doing things correctly:/
>>
>> >//
>>
>> >/Ferret v6.93/
>>
>> >/yes? use file.nc/
>>
>> >/   *** NOTE: Axis definition error on axis: time. Bounds describe 
>> cells that/
>>
>> >/overlap one another/
>>
>> which made me think that overlap was an error.  But reading more 
>> context I see it is just a “note”, not an “error”, and clearly 
>> overlapping bounds are accepted.
>>
>> For my situation of overlapping vertical trapezoids, I now think I 
>> should use the full overlapping extent in the “bounds” variable and 
>> explain the full shape of the trapezoids in the main variable’s 
>> description attribute.
>>
>> Is there a better way to communicate the full situation?
>>
>>   -- Evan
>>
>> *From: *Jim Biard <jbiard at cicsnc.org>
>> *Date: *Friday, March 3, 2017 at 5:09 AM
>> *To: *<cf-metadata at cgd.ucar.edu>
>> *Subject: *Re: [CF-metadata] Overlapping vertical bounds
>>
>> What makes you think overlapping bounds are illegal?
>>
>> On 3/2/17 7:20 PM, Manning, Evan M (398B) wrote:
>>
>>     I have some quantities which are defined on trapezoids in the
>>     vertical direction.
>>
>>     For example the top trap might be full weight from the top of the
>>     atmosphere (TOA) to 50 hPa, then we ramp linearly between the
>>     first and second traps between 50 & 75 hPa, then trap 2 is full
>>     weight 75-100 hPa, followed by another transition in [100, 125]
>>     hPa, etc.
>>
>>     I can’t have a bounds variable with the full extent of each trap
>>     like [ [0, 75], [50, 125], [100, … because overlap is illegal.
>>
>>     I could have underlap, just giving the intervals where each trap
>>     is in full force: [ [0, 50], [75, 100], …
>>
>>     Or I could use the midpoints of the transitions: [ [ 0, 62.5],
>>     [62.5, 112.5], …
>>
>>     I’d prefer to find a standard way to communicate the precise
>>     situation.  Is there one?
>>
>>       -- Evan
>>
>>
>>
>>
>>     _______________________________________________
>>
>>     CF-metadata mailing list
>>
>>     CF-metadata at cgd.ucar.edu <mailto:CF-metadata at cgd.ucar.edu>
>>
>>     http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>
>> -- 
>>
>> *ICS-NC* <http://www.cicsnc.org/>Visit us on
>> *Facebook * <http://www.facebook.com/cicsnc>
>>
>> 	
>>
>> *Jim Biard*
>> *Research Scholar*
>> *Cooperative Institute for Climate and Satellites NC * 
>> <http://cicsnc.org/>
>> *North Carolina State University * <http://ncsu.edu/>
>> *NOAA National Centers for Environmental Information * 
>> <http://ncdc.noaa.gov/>
>> /formerly NOAA’s National Climatic Data Center/
>> 151 Patton Ave, Asheville, NC 28801
>> e: jbiard at cicsnc.org <mailto:jbiard at cicsnc.org>
>> o: +1 828 271 4900
>>
>> /Connect with us on Facebook for climate 
>> <https://www.facebook.com/NOAANCEIclimate> and ocean and geophysics 
>> <https://www.facebook.com/NOAANCEIoceangeo> information, and follow 
>> us on Twitter at @NOAANCEIclimate 
>> <https://twitter.com/NOAANCEIclimate> and @NOAANCEIocngeo 
>> <https://twitter.com/NOAANCEIocngeo>. /
>>
>>
>>
>> _______________________________________________
>> CF-metadata mailing list
>> CF-metadata at cgd.ucar.edu
>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.cgd.ucar.edu/pipermail/cf-metadata/attachments/20170306/1677db44/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/png
Size: 15785 bytes
Desc: not available
URL: <http://mailman.cgd.ucar.edu/pipermail/cf-metadata/attachments/20170306/1677db44/attachment-0001.png>


More information about the CF-metadata mailing list