Dear Martin and Karl I'm not sure I have understood this. Writing out what Martin first said at greater length, does it mean
mass of rainfall (in kg, meaning the area- and time-integral rainfall flux in kg m-2 s-1) which falls onto the snow-covered portion of the gridbox in a certain time-interval, divided by the mass of rainfall (in the same sense) which falls onto the entire gridbox in the same time-interval? and the same for "precipitation" and "snowfall" instead of "rainfall"? If so, I have some suggestions regarding > fraction_of_precipitation_mass_falling_on_snow > fraction_of_rain_mass_falling_on_snow > fraction_of_snow_mass_falling_on_snow First, I think we could use "rainfall_amount" and "snowfall_amount" as Martin first said, because these are time-accumulations, aren't they? They are actually the gridbox precipitation/rainfall/snowfall_amount multiplied by the area fraction of the gridbox which is covered by snow. I think this would be preferable because we currently don't have terms with "mass" for precipitation. On the other hand, you could prefer "mass" if you write it as I did above and regard it as a mass fraction. In that case I would advocate "precipitation/rainfall/snowfall_mass" i.e. insert "fall". This is because "snowmass" could be misunderstood to mean the mass of lying snow - a sense in which the word is often used. Including "fall" would make these mass terms look like the existing amount, content, flux and rate terms. However I still prefer "amount". Second, I think "onto", as Martin said, is better than "on". It makes it clearer (again) that it's been added. Third, instead of onto_snow I would say onto_surface_snow, because we have consistently used the phrase surface_snow to mean snow lying on the ground, to be absolutely clear we don't mean snowfall. Since we have to talk about both snowfall and lying snow in one standard name here, clarity is useful about which is which. If it means snow and ice, not just snow, then we can say surface_snow_and_ice, which is a phrase already used. Thus I end up with fraction_of_precipitation/rainfall/snowfall_amount_falling_onto_surface_snow and if that's still not quite transparent to parse, we could consider saying which_falls instead of falling. Neither is yet used in standard names. Best wishes Jonathan ----- Forwarded message from Martin Juckes - UKRI STFC <[email protected]> ----- > Date: Fri, 1 Jun 2018 06:42:45 +0000 > From: Martin Juckes - UKRI STFC <[email protected]> > To: Karl Taylor <[email protected]>, "[email protected]" > <[email protected]> > Subject: Re: [CF-metadata] Precipitation fractions for LS3MIP > > Hi Karl, > > > Thanks, that looks better. I was trying to stick close to existing patterns, > but the outcome was a bit contrived and, I agree, not very satisfactory. > > > Sorry about the confusion, the two terms we need are: > > fraction_of_rain_mass_falling_on_snow > fraction_of_snow_mass_falling_on_snow > > > However, I need to check with LS3MIP whether they intend "snowfall" to > include snow and ice, as for the CMIP5 variable "prsn", > > > regards, > > Martin > > > ________________________________ > From: CF-metadata <[email protected]> on behalf of Karl Taylor > <[email protected]> > Sent: 31 May 2018 19:11 > To: [email protected] > Subject: Re: [CF-metadata] Precipitation fractions for LS3MIP > > Hi Martin, > > For CMIP6, I think we define precipitation = rainfall + snowfall . > > So do you want to collect "precipitation amount" or "rainfall amount" > (in addition to "snowfall amount")? You first mention "rainfall" below, > but later propose a name for "precipitation". > > I also think it is a bit confusing that in this name "amount" refers to > the amount accumulated over some time-period (e.g., a day or a month), > rather than the total "content" that exists at a given point in time. > > I might suggest as alternatives: > > fraction_of_precipitation_mass_falling_on_snow > fraction_of_rain_mass_falling_on_snow > fraction_of_snow_mass_falling_on_snow > > best regards, > Karl > > > On 5/31/18 9:56 AM, Martin Juckes - UKRI STFC wrote: > > Hello All, > > > > > > There are two LS3MIP variables for fractions of precipitation onto snow: > > fraction of rainfall on snow and fraction of snowfall on snow. In both > > cases the fraction is calculated as the mass of precipitation falling on > > snow divided by the total mass of precipitation in the grid cell. > > > > > > Since we are dealing with mass, the term should start from > > precipitation_amount and snowfall_amount. > > > > > > We have terms like lwe_thickness_of_precipitation_amount to describe > > properties of the precipitation amount, and we have > > precipitation_flux_onto_canopy do describe a flux onto a particular > > surface, so I propose: > > > > fraction_of_precipitation_amount_onto_snow and > > > > fraction_of_snowfall_amount_onto_snow, both with units '1', > > > > > > regards, > > > > Martin > > > > > > > > > > _______________________________________________ > > CF-metadata mailing list > > [email protected] > > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > _______________________________________________ > 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
