On Tue, Jan 2, 2018 at 12:24 PM, V Balaji - NOAA Affiliate <
v.balaji at noaa.gov> wrote:
> I would not recommend UGRID for non-standard but structured (e.g logically
> rectangular) grids.
nor would I.
> I'm not aware of anyone planning to turn in data on a completely
> unstructured grid in CMIP6.
>
than not an issue, but there are hex grids, which may well be structured,
and not rectangular....So not sure the best option there.
-CHB
> 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>
>>>
>>
>>
>>
> --
> V. Balaji Office: +1-609-452-6516
> Head, Modeling Systems Group, GFDL Mobile: +1-917-273-9824
> Princeton University Email: v.balaji at noaa.gov
> https://www.gfdl.noaa.gov/v-balaji-homepage
--
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
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