Dear Alex > I have a question on the time variable of a monthly climatologies collecting > e.g. all data from > 1900-01-01 to 2000-12-31. > As I understand the standard > (http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/cf-conventions.html#climatological-statistics), > I should use the following: > > dimensions: > time=12; > nv=2; > variables: > float temperature(time,lat,lon); > temperature:cell_methods="*time: mean within years time: mean over > years*"; > double time(time); > time:climatology="climatology_bounds"; > time:units="days since 1900-1-1"; > double climatology_bounds(time,nv); > data: // time coordinates translated to date/time format > time="1900-1-16", "1900-2-16", "1900-3-16", "1900-4-16", ... "1900-12-16"; > climatology_bounds="1900-1-1", "2000-2-1", > "1900-2-1", "2000-3-1", > .... > "1900-11-1", "2001-12-1"; > > > I use the standard Gregorian calendar. Can you confirm that the used > cell_methods and > climatology_bounds are correct?
They look correct to me. Although the standard calendar is the default, it would do no harm, and might be informative, to include a calendar attribute. You can check that your metadata is correct by using the CF checker on the CF website. > I am not so sure about the cell method since the WOA 2009 climatology uses > "time:mean within > *months* time:mean over *months*" for monthly climatologies > (http://data.nodc.noaa.gov/thredds/dodsC/woa/WOA09/NetCDFdata/temperature_monthly_1deg.nc.info). That is incorrect. I think the CF checker would report that error. It would be good if NODC could correct the error - I wonder if we have any NODC subscribers on this list. > I am wondering if it would not have been easier to define climatology_bounds > as an array with the > starting and end dates of *all *subintervals (not just the start for the > first and the end of the > last subinterval). It would be simpler to find out to which time slice of the > climatological > variable an individual observation would relate to. It would also allow to > make climatologies over > other cycles (e.g. tides) or non-periodic processes (e.g. ENSO). To calculate climatologies over arbitrary periods, you would need the original monthly data, wouldn't you, not the monthly climatology. A non-climatological dataset has time bounds for each individual time interval, as you describe. Best wishes Jonathan _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
