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 I?m 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
>>
>>
>>
>>
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>>
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>>
>> *Jim Biard*
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Received on Mon Mar 06 2017 - 11:19:53 GMT
