On Wed, Mar 30, 2016 at 1:09 PM, Ethan Davis <eda...@ucar.edu> wrote:
> Yes, though I'm not that familiar with the details of UGRID, it does (now > that you mention it) seem related in some ways to the river/basin topic. > well, maybe -- but while UGRIDs are "unstructured", there is SOME structure to them -- i.e. they are usually made up of cells with the same number of sides (triangles, quads, etc), or at least a small number (six or less). And the UGRID data structure does assume this. > I've been thinking of the river/basin > Rivers can be a 1-d "mesh" which there is support in UGRID for, but I think of basins as being arbitrary often high order polygons. Is there any standard for supporting polygons (i.e. what you might put in shape files) in netcdf? -Chris > On Tue, Mar 29, 2016 at 6:43 AM, Jonathan Gregory < > j.m.greg...@reading.ac.uk> wrote: > >> Dear Ethan >> >> I agree with Steve about ugrid and aggregation being important topics. >> >> > 1. "UGRID" >> >> The ugrid design is rather CF-compatible and it would be good if they >> could be >> cemented together somehow. ugrid could be a proposed as a chapter of CF >> but it >> doesn't have to be, of course. I suppose the advantage of doing so would >> be >> that CF and ugrid development would subsequently remain compatible. >> >> Could ugrid deal with this one of your agenda items: >> >> > * Drafting a CF enhancement that would add support for complex data >> > footprints (e.g., river segments and drainage basins) >> >> I'm not sure what you have in mind but it sounds possibly related. >> >> > 2. "Aggregation" -- CF structures to link multiple files into larger >> > conceptual datasets. Time series aggregations, union aggregations >> > (associated variables in separate files), and ensemble membership >> > are the most obvious applications of this. Another important >> > application is "tiled grids" (ref. the "gridspec" proposal). >> >> There are various types of aggregation which should be distinguished, I >> think. >> >> * Aggregation of variables. This is needed when one variable is split >> among >> several files (often along the time axis) but it can also apply to >> variables in >> the same file (for instance combining ensemble members or time series >> with the >> same time coordinates - Steve's other examples). In general it means >> combining >> several variables to make one variable, by concatenating one or more of >> their >> axes. This can be done entirely using CF metadata and David Hassell and I >> wrote >> a CF proposal for it http://cf-trac.llnl.gov/trac/ticket/78 a long time >> ago, >> which David has since implemented in cf-python software. I believe that >> this >> approach is fine for CMIP6 purposes, for example. >> >> * Aggregation of domains. By this I mean regarding domains which have >> their >> own axes as part of a larger domain, like gridspec does. It's not >> aggregation >> of variables in the same sense as above because the axes can't be >> concatenated. >> It is similar to ugrid, though, and I think it would be good if an >> extension >> to CF like ugrid could be developed for this. >> >> * Aggregation of files. By this I mean regarding several files as one file >> *without* associating or joining variables together, just putting them >> into >> one container. This needs rules for dealing with collisions of identically >> named variables, like NCO ncks has, or groups could be used, which are >> also on >> Ethan's agenda. >> >> > Harmonizing CF grid mapping with OGC CRS (coordinate reference >> > systems), possibly with WKT >> >> It should be possible to translate between CF and OGC CRS descriptions. >> Some >> extensions to help with this are in >> http://cf-trac.llnl.gov/trac/ticket/80, >> which will be in CF 1.7, as will http://cf-trac.llnl.gov/trac/ticket/69, >> which >> allows WKT to be stored in a CF attribute. CF and OGC CRS have different >> views >> of the data space, so I don't think we can expect to make them look the >> same, >> but we should be able to define a mapping for all those concepts which >> are in >> both. >> >> Best wishes >> >> Jonathan >> >> ----- Forwarded message from Ethan Davis <eda...@ucar.edu> ----- >> >> > Date: Sun, 27 Mar 2016 22:24:56 -0600 >> > From: Ethan Davis <eda...@ucar.edu> >> > To: CF metadata <cf-metadata@cgd.ucar.edu>, netCDF SWG >> > <netcdf....@lists.opengeospatial.org> >> > Subject: [CF-metadata] Meeting invite: Advancing netCDF-CF, 24-26 May >> 2016, >> > Boulder, CO, USA >> > >> > Hi all, >> > >> > As some of you have heard, we are holding a meeting to discuss current >> and >> > future netCDF-CF efforts and directions. The meeting will be held on >> 24-26 >> > May 2016 in Boulder, CO, USA at the UCAR Center Green facility. >> > >> > This meeting is organized by the “Advancing netCDF-CF for Geoscience” >> > project [1] which has been funded by the US NSF EarthCube program. The >> > project goals include several specific CF development efforts, both >> > standards development and software prototyping. (We are just starting to >> > spin-up community conversations around these specific goals for >> drafting CF >> > extensions.) Another aspect of the funded project is community >> engagement >> > including with the existing CF community, geoscience domains that have >> not >> > been very involved in CF, and other standards bodies (e.g., OGC). These >> and >> > other topics are on the current list of possible agenda items. Please >> let >> > us know if you have other agenda items in mind. >> > >> > The current list of possible agenda items includes: >> > >> > - Investigate using features of the netCDF enhanced data model to >> > improve/simplify the CF Discrete Sampling Geometries (which includes >> point, >> > sounding, and trajectory data types) >> > - Drafting a CF enhancement that would add support for complex data >> > footprints (e.g., river segments and drainage basins) >> > - Further develop the CFRadial proposal for representing Radar data >> > - Adding features to better support satellite data >> > - Adding CF support for hierarchical groups for organizing data and >> > metadata >> > - Enhancing CF to support Linked Data / semantic technology concepts >> > - Harmonizing CF grid mapping with OGC CRS (coordinate reference >> > systems), possibly with WKT >> > - Adding CF support for attribute namespaces and the use of URI >> prefixes >> > in attribute values >> > - Improved support for dimensionless data variables, logarithmic >> scales, >> > differences, etc. >> > >> > While we wish we could host all those interested in attending, given the >> > available meeting space and the number of project participants, we are >> > asking members of the CF community that are interested in attending to >> > contact us directly and let us know which aspects of CF are of interest >> to >> > you and your goals for the meeting. Please submit your expressions of >> > interest by Monday, 4 April 2016. We plan to invite participants by >> Friday, >> > 8 April 2016. >> > >> > Travel and other information will be on the meeting page [2] later this >> > week. >> > >> > Also, for anyone attending EGU in Vienna in April, we will have a >> splinter >> > meeting (SMP32) to discuss netCDF-CF. The splinter meeting will be held >> on >> > Thursday, 21 April 2016 at 15:30 in room 2.96. >> > >> > Thank you, >> > >> > Meeting Organizers >> > >> > Ethan Davis, UCAR Unidata >> > Charlie Zender, Univ of CA, Irvine >> > David Arctur, Univ of TX, Austin >> > Dave Santek, Univ of WI, Madison / SSEC >> > Kevin O’Brien, Univ of WA/JISAO and NOAA/PMEL >> > Aleksandar Jelenak, The HDF Group >> > Mike Dixon, NCAR/EOL >> > >> > [1] http://www.nsf.gov/awardsearch/showAward?AWD_ID=1541031 >> > >> > [2] http://www.unidata.ucar.edu/events/2016CFWorkshop/ >> >> > _______________________________________________ >> > CF-metadata mailing list >> > CF-metadata@cgd.ucar.edu >> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >> >> >> ----- End forwarded message ----- >> _______________________________________________ >> CF-metadata mailing list >> CF-metadata@cgd.ucar.edu >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >> > > > _______________________________________________ > CF-metadata mailing list > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > -- 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.bar...@noaa.gov
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