Hi All, I haven't noticed any discussion in the email stream about the type of diameter.
There are several physically different diameters that get used in the aerosol community, the main ones being: 1) Actual, or geometric diameter (But what does that mean for non-spherical particles? Some are very non-spherical.) 2) Effective diameter (Volume divided by surface area [with a 1/3 geometric factor]. Avoids ambiguity for non-spherical particles.) 3) Aerodynamic diameter (defined by its settling velocity: the diameter of a spherical drop with density of 1g/cm3 that will settle at the same rate as the particle of interest). Since 2 & 3 can differ by more than a factor of two, it can make quite a difference Best wishes, Philip ----------------------------------------------------------------------- Dr Philip Cameron-Smith, p...@llnl.gov, Lawrence Livermore National Lab. ----------------------------------------------------------------------- > -----Original Message----- > From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata- > boun...@cgd.ucar.edu] On Behalf Of alison.pamm...@stfc.ac.uk > Sent: Monday, November 29, 2010 4:35 AM > To: cf-metadata@cgd.ucar.edu > Subject: Re: [CF-metadata] Correct name for aerosol size > distributionexpressedin numbers ? > > Dear Bruno, Jonathan and Roy, > > Thanks all for your comments. As far as the standard name is > concerned, > I think we are agreed on aerosol_particle_diameter to describe the > particle sizes. This would have an SI unit of m. > > This name is accepted for inclusion in the standard name table. > > ------ > Alison Pamment Tel: +44 1235 778065 > NCAS/British Atmospheric Data Centre Fax: +44 1235 446314 > Rutherford Appleton Laboratory Email: > alison.pamm...@stfc.ac.uk > Chilton, Didcot, OX11 0QX, U.K. > > > > -----Original Message----- > > From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata- > > boun...@cgd.ucar.edu] On Behalf Of Jonathan Gregory > > Sent: 27 November 2010 14:21 > > To: cf-metadata@cgd.ucar.edu > > Subject: [CF-metadata] Correct name for aerosol size > > distributionexpressedin numbers ? > > > > Dear Bruno > > > > Either the geophysical quantity or the bin index could be the > > coordinate > > variable, with the other one being an auxiliary coordinate variable. > > That > > is an arbitrary choice. If you don't need the bin index, you don't > have > > to > > have such a variable at all. Both > > > > SPP200_bins = 30 ; > > int SPP200_bins(SPP200_bins) ; > > float SPP200_median_particle_diameter(SPP200_bins) ; > > float mic_conctab_SPP200_sync_1(time, SPP200_bins) ; > > mic_conctab_SPP200_sync_1:coordinates = > > "SPP200_median_particle_diameter" ; > > > > and > > > > SPP200_median_particle_diameter = 30; > > int SPP200_bins(SPP200_median_particle_diameter) ; > > float > > SPP200_median_particle_diameter(SPP200_median_particle_diameter); > > float mic_conctab_SPP200_sync_1(time, > > SPP200_median_particle_diameter) ; > > mic_conctab_SPP200_sync_1:coordinates = "SPP200_bins"; > > > > would be OK. time does not need to be named in the coordinates > > attribute, > > since it is a coordinate variable. (You can list it there if you > like, > > but > > it is not usual.) > > > > > One last question I couldn't solve : should > > > "bounds="SPP200_bin_bounds" be a attribute of the simple index > > variable > > > ("SPP200_bins") or of the the geophysices coordinate > > > ("SPP200_median_particle_diameter") ? > > > > The latter. It specifies bounds for the diameter values for the bins. > > > > Best wishes > > > > Jonathan > > _______________________________________________ > > CF-metadata mailing list > > CF-metadata@cgd.ucar.edu > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > -- > Scanned by iCritical. > _______________________________________________ > 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