Dear Martin The reason for giving names to the transects and basins is because they are numerically a bit imprecise - they will differ from model to model - but still the Atlantic in one model should be regarded as comparable to the Atlantic in another model, etc. I agree we do not have a way at present to record precisely what it means in a given case. Since transects might be jagged lines and coasts always are, a more general solution than endpoints would be a way to associate a named line or outline (a geographical feature) with a list of coordinates that trace it out, perhaps. Is there a use-case for this extra metadata? Has it been requested in CMIP6?
Best wishes Jonathan ----- Forwarded message from [email protected] ----- > Date: Mon, 29 Jun 2015 12:31:37 +0000 > From: [email protected] > To: [email protected] > Subject: [CF-metadata] Specifying latitude and longitude of transects and > regions > > Hello All, > > There are some variables in the CMIP5 archive which lack explicit latitude > and longitude information, such as mfo (standard name > sea_water_transport_across_line) and msftzzzba > (ocean_y_overturning_mass_streamfunction_due_to_bolus_advection). The first > is a mass flux across a transect and the second is a zonally averaged stream > function, averaged across an ocean basin. > > For transects, the mfo variable is encoded with an index dimension and a > coordinate "passage" which labels transects by the name of the passage they > cross (e.g. fram_strait). The information about precisely which part of the > Fram Strait is used is in a document referred to from the MIP tables. It > would be nice to have a means of encoding the end points of the transect in > the CF metadata. I looked into using the "bounds" attribute, but that is > defined to represent cell boundaries, so an extension to the convention is, I > think, needed. It makes sense to follow the pattern used to represent cell > boundaries. I propose defining a new attribute "transect" which, like the > "bounds" attribute, can be attached to coordinate variables and takes the > name of another variable as its value. The named variable should contain the > end points of the transect. > > The same approach could be used for the streamfunction .. which is a mean > across an east-west transect (this approach would lead to a specifcation of > the east and west endpoints of each basin at each latitude -- but I'm not > sure that it would be feasible to collect that much detail in the CMIP data > files). > > Is there a cleaner way of encoding transect and basin coordinates? > > regards, > Martin > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata ----- End forwarded message ----- _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
