On Tue, Jan 2, 2018 at 12:24 PM, V Balaji - NOAA Affiliate < [email protected]> 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 <[email protected] <mailto: >>> [email protected]>> 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 >>> >>> [email protected] <mailto:[email protected]> >>> >> >> >> > -- > V. Balaji Office: +1-609-452-6516 > Head, Modeling Systems Group, GFDL Mobile: +1-917-273-9824 > Princeton University Email: [email protected] > 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 [email protected]
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