[CF-metadata] Recording "day of year on which something happens"
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-- Antonio S. Cofi?o Associate Professor and Researcher Grupo de Meteorolog?a de Santander Dep. of Applied Mathematics and Computer Sciences Universidad de Cantabria (Spain) Academic Visitor National Centre for Atmospheric Science Department of Meteorology School of Mathematical, Physical and Computational Sciences University of Reading (UK) http://antonio.cofino.es On 15/03/17 18:16, Jim Biard wrote: > > Dan, > > How about that? I'm working on similar products. We haven't even > considered standard names for them. > > I went ahead and used 'days since YYYY-MM-DD 00:00:00' for my first > and last frost dates, since they are valid dates. My files are > structured as (example for first frost date): > > dimensions: > time = UNLIMITED ; // (56 currently) > lon = 960 ; > lat = 490 ; > bnds = 2 ; > variables: > double time(time) ; > time:standard_name = "time" ; > time:long_name = "time" ; > time:axis = "T" ; > time:units = "days since 1900-01-01 00:00:00" ; > time:calendar = "gregorian" ; > time:bounds = "time_bounds" ; > double time_bounds(time, bnds) ; > double lon(lon) ; > lon:standard_name = "longitude" ; > lon:long_name = "longitude" ; > lon:units = "degrees_east" ; > lon:modulo = 360. ; > lon:axis = "X" ; > lon:bounds = "lon_bounds" ; > double lon_bounds(lon, bnds) ; > double lat(lat) ; > lat:standard_name = "latitude" ; > lat:long_name = "latitude" ; > lat:units = "degrees_north" ; > lat:axis = "Y" ; > lat:bounds = "lat_bounds" ; > double lat_bounds(lat, bnds) ; > float first_freeze_date(time, lat, lon) ; > first_freeze_date:_FillValue = 1.e+20f ; > first_freeze_date:missing_value = 1.e+20f ; > first_freeze_date:comment = "Date of the first day > with a minimum temperature at or below 0 degrees C over the 9 > month period starting Aug 1 of each year." ; > first_freeze_date:flag_meanings = > "No_Freeze_Following" ; > first_freeze_date:long_name = "First freeze date" ; > first_freeze_date:valid_min = 0. ; > first_freeze_date:flag_values = -2. ; > first_freeze_date:units = "days since 1900-01-01 > 00:00:00" ; > first_freeze_date:calendar = "standard" ; > > with the time bounds reflecting 1 Aug to 1 May for each year. > > On 3/15/17 1:50 PM, Hollis, Dan wrote: >> >> Hi Jon, >> >> I?d be interested to know how to tackle this problem too. I?ve >> recently been generating some datasets of ?date of first frost? and >> ?date of last frost? and have no idea how to describe them in a >> CF-compliant way. >> >> Jim?s suggestion of ?day_of_year? is better than just ?days?, however >> this doesn?t capture what the ?something? is that has happened, nor >> that is the first/last/Nth occurrence of that event. What sort of >> events are you looking at? >> >> In my application I?m just looking at UK data, hence my ?year? runs >> from 1^st July to 30^th June (to span the N Hemisphere winter). It?s >> easy enough to use the bounds to indicate this, but I?m then not sure >> what values to store in the data array. Number of days since 1^st >> July maybe? Or ordinal date (1^st Jan = 1, 31^st Dec = 365)? >> >> Dan >> >> PS I have a whole bunch of other metrics that I?m looking at e.g. >> length of the longest spell, number of spells greater then N days >> etc. These seem even more complicated to describe using CF. Something >> for another post I think... >> >> *From:*CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] *On >> Behalf Of *Jim Biard >> *Sent:* 15 March 2017 16:28 >> *To:* cf-metadata at cgd.ucar.edu >> *Subject:* Re: [CF-metadata] Recording "day of year on which >> something happens" >> >> Jon, >> >> I agree that a cell_methods attribute doesn't seem to be necessary. A >> new standard_name like 'day_in_year' or 'day_of_year' would likely >> make things clearer. >> >> Jim >> >> On 3/15/17 11:22 AM, Jon Blower wrote: >> >> Thanks Jim, that?s very helpful. Is cell_methods necessary in >> this case (for the time axis bounds) ? probably not since this >> isn?t a statistical quantity like an average, but a value that?s >> ?representative? of the year. >> >> I seem to remember from a while back that there was a proposal to >> allow time axes to use ?calendar years since X? (as opposed to >> ?years since X?, which uses a fixed-length UDUNITS year), which >> might handle this use case. I have been out of the loop for a >> while, but I can?t find mention of that in the CF spec, so maybe >> that didn?t go through. >> >> I might consider requesting a new standard name ? ?days? is good, >> but I wonder if a more specific one would be helpful. >> >> Best wishes, >> Jon >> >> *From: *CF-metadata <cf-metadata-bounces at cgd.ucar.edu> >> <mailto:cf-metadata-bounces at cgd.ucar.edu> on behalf of Jim Biard >> <jbiard at cicsnc.org> <mailto:jbiard at cicsnc.org> >> *Date: *Tuesday, 14 March 2017 15:12 >> *To: *"cf-metadata at cgd.ucar.edu" >> <mailto:cf-metadata at cgd.ucar.edu> <cf-metadata at cgd.ucar.edu> >> <mailto:cf-metadata at cgd.ucar.edu> >> *Subject: *Re: [CF-metadata] Recording "day of year on which >> something happens" >> >> Jon, >> >> 1) I'd use 'days'. It is a valid standard name apart from the >> 'days since date' formalism. It's not perfect, but it's legal. >> You could, alternatively, request a new standard name. >> >> 2) Use a time_bounds variable. I would tend to set the time to be >> July 1 at midnight for each year, and set the bounds for each >> year to Jan 1 of that year and Jan 1 of the next year. >> >> Grace and peace, >> >> Jim >> >> On 3/14/17 10:43 AM, Jon Blower wrote: >> >> Hi all, >> >> >> >> We need to structure a NetCDF file that will hold a variable that represents the day of the year on which an event happened (integers from 0 to 366). This value is recorded every year for a number of years. I have a couple of questions about how best to do this: >> >> >> >> 1. What is the best standard name to use for the day of the year? I didn?t find anything in the standard name table, although I might have missed it. >> >> >> >> 2. What would be the best way to define the time axis? Each point along the axis would represent a whole year, rather than an instant in time. I could simply pick an arbitrary instant (e.g. midnight on 1st Jan) to represent the year, but is there a better way? >> >> >> >> Thanks in advance for any help! >> >> >> >> Jon >> >> >> >> _______________________________________________ >> >> CF-metadata mailing list >> >> CF-metadata at cgd.ucar.edu <mailto:CF-metadata at cgd.ucar.edu> >> >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >> >> -- >> >> *ICS-NC* <http://www.cicsnc.org/>Visit us on >> *Facebook * <http://www.facebook.com/cicsnc> >> >> >> >> *Jim Biard* >> *Research Scholar* >> *Cooperative Institute for Climate and Satellites NC * >> <http://cicsnc.org/> >> *North Carolina State University * <http://ncsu.edu/> >> *NOAA National Centers for Environmental Information * >> <http://ncdc.noaa.gov/> >> /formerly NOAA?s National Climatic Data Center/ >> 151 Patton Ave, Asheville, NC 28801 >> e: jbiard at cicsnc.org <mailto:jbiard at cicsnc.org> >> o: +1 828 271 4900 >> >> /Connect with us on Facebook for climate >> <https://www.facebook.com/NOAANCEIclimate> and ocean and >> geophysics <https://www.facebook.com/NOAANCEIoceangeo> >> information, and follow us on Twitter at _at_NOAANCEIclimate >> <https://twitter.com/NOAANCEIclimate> and _at_NOAANCEIocngeo >> <https://twitter.com/NOAANCEIocngeo>. / >> >> -- >> >> *CICS-NC* <http://www.cicsnc.org/>Visit us on >> *Facebook * <http://www.facebook.com/cicsnc> >> >> >> >> *Jim Biard* >> *Research Scholar* >> *Cooperative Institute for Climate and Satellites NC * >> <http://cicsnc.org/> >> *North Carolina State University * <http://ncsu.edu/> >> *NOAA National Centers for Environmental Information * >> <http://ncdc.noaa.gov/> >> /formerly NOAA?s National Climatic Data Center/ >> 151 Patton Ave, Asheville, NC 28801 >> e: jbiard at cicsnc.org <mailto:jbiard at cicsnc.org> >> o: +1 828 271 4900 >> >> /Connect with us on Facebook for climate >> <https://www.facebook.com/NOAANCEIclimate> and ocean and geophysics >> <https://www.facebook.com/NOAANCEIoceangeo> information, and follow >> us on Twitter at _at_NOAANCEIclimate >> <https://twitter.com/NOAANCEIclimate> and _at_NOAANCEIocngeo >> <https://twitter.com/NOAANCEIocngeo>. / >> > > -- > CICS-NC <http://www.cicsnc.org/> Visit us on > Facebook <http://www.facebook.com/cicsnc> *Jim Biard* > *Research Scholar* > Cooperative Institute for Climate and Satellites NC <http://cicsnc.org/> > North Carolina State University <http://ncsu.edu/> > NOAA National Centers for Environmental Information > <http://ncdc.noaa.gov/> > /formerly NOAA?s National Climatic Data Center/ > 151 Patton Ave, Asheville, NC 28801 > e: jbiard at cicsnc.org <mailto:jbiard at cicsnc.org> > o: +1 828 271 4900 > > /Connect with us on Facebook for climate > <https://www.facebook.com/NOAANCEIclimate> and ocean and geophysics > <https://www.facebook.com/NOAANCEIoceangeo> information, and follow us > on Twitter at _at_NOAANCEIclimate <https://twitter.com/NOAANCEIclimate> > and _at_NOAANCEIocngeo <https://twitter.com/NOAANCEIocngeo>. / > > > > > _______________________________________________ > CF-metadata mailing list > CF-metadata at cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata -------------- next part -------------- An HTML attachment was scrubbed... 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