I would not recommend UGRID for non-standard but structured (e.g logically rectangular) grids. I'm not aware of anyone planning to turn in data on a completely unstructured grid in CMIP6.
Thanks, and best wishes to everyone for 2018,
Karl Taylor writes:
> In CMIP we require that? both missing_value and _FillValue be defined as
> 1.e20 for requested variables that occupy only a portion of the global grid.?
> For bounds variables, I'll suggest that when needed, both _FillValue and
> missing_value also be defined as 1.e20. That way software that relies on
> either one will work.
>
> My understanding of UGRID is that it provides for a much fuller description
> of a grid than CF.? For CMIP, I think we can recommend UGRID be used for
> non-standard grids, but I'm reluctant to require it.? Most grids for most
> purposes I think can be adequately described with the CF-mandated
> attributes.? Does anyone disagree?
>
> thanks,
> Karl
>
> On 1/1/18 4:47 PM, Chris Barker wrote:
>> On Wed, Dec 20, 2017 at 2:21 PM, Karl Taylor <taylor13 at llnl.gov
>> <mailto:taylor13 at llnl.gov>> wrote:
>>
>>
>> My sense is that no one violently opposes the use of missing_value
>> to fill unused vertices for grid cells with fewer than the maximum
>> number of vertices.
>>
>>
>> I'm pretty sure this has been brought this up before (at least suggesting
>> that UGRID be consulted )but UGRID uses _FillValue , rather than
>> missing_value:
>>
>> http://ugrid-conventions.github.io/ugrid-conventions/#2d-flexible-mesh-mixed-triangles-quadrilaterals-etc-topology
>>
>> I have no recollection as to why that was chosen, but I encourage you not
>> to do something different than an existing standard without good reason.
>>
>> For CMIP6 some models may need to define grids with a few cells
>> having one less vertex than the majority.? I am (much too late in
>> the process) writing down the data requirements for CMIP6 model
>> output,
>>
>>
>> Any reason CMIP shouldn't specify the? UGRID standard and be done with it?
>>
>> If there is something missing from the UGRID standard that is needed,
>> please let us know, and ideally propose an addition.
>>
>> -CHB
>>
>>
>>
>> --
>>
>> Christopher Barker, Ph.D.
>> Oceanographer
>>
>> Emergency Response Division
>> NOAA/NOS/OR&R ? ? ? ? ? ?(206) 526-6959?? voice
>> 7600 Sand Point Way NE ??(206) 526-6329?? fax
>> Seattle, WA ?98115 ? ? ??(206) 526-6317?? main reception
>>
>> Chris.Barker at noaa.gov <mailto:Chris.Barker at noaa.gov>
>
>
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Received on Tue Jan 02 2018 - 13:24:10 GMT
