Dear Chris,
Thanks for your comments on these names.
1. "Thickness" is the term generally used in CF standard names to describe the vertical extent of a layer. For example, we have the existing names atmosphere_boundary_layer_thickness and ocean_mixed_layer_thickness, and there are quite a number of others that follow this pattern. Therefore I think flood_water_thickness is the correct term for the new name.
2. The name as proposed can be used with a vertical coordinate variable or scalar coordinate variable to specify the altitude/height above the solid earth surface to which the speed applies. So you could have a speed that varies in the vertical or a mean speed representative of the whole flood_water layer. If the latter is required, you would use a scalar vertical coordinate with coordinate bounds specifying the full extent of the layer and a cell_methods of "altitude: mean". If the data values were simply taken from a representative level you would do the same thing except to specify a cell_methods of "altitude:point", I think. This flexibility means that we don't need to be prescriptive about vertical processing in the standard name definition.
3. Indeed this is a new name (distinct from the existing name surface_altitude). It is longstanding CF practice that we don't add new standard names unless someone has an actual need for them. Occasionally, this may lead to "gaps" in the standard name table which some people find surprising, but if a commonly used quantity is "missing" it simply means that no one has ever asked for it :)
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
Centre for Environmental Data Analysis Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
From: Chris Barker [mailto:chris.barker at noaa.gov]
Sent: 16 September 2015 18:54
To: Pamment, Alison (STFC,RAL,RALSP)
Cc: Eizi TOYODA; cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] new standard names for flood simulation
All good.
A couple nitpicky questions:
1. flood_water_thickness (m)
I'd expect this to be "flood_water_depth" -- never heard the term thickness used. Or does that use of depth conflict with a definition elsewhere. In which case, maybe a note is in order.
2. flood_water_speed (m s-1)
'Speed is the magnitude of velocity. Flood water is water that covers land which is normally not covered by water.'
id this depth-averaged, or at a given depth, height, etc? or is that distinction defined elsewhere depending on use??
5. ground_level_altitude (m)
'The ground_level_altitude is the geometric height of the upper boundary of the solid Earth above the geoid, which is the reference geopotential surface. The geoid is similar to mean sea level.'
we really don't already have this? interesting....
But good stuff overall.
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R ? ? ? ? ? ?(206) 526-6959?? voice
7600 Sand Point Way NE ??(206) 526-6329?? fax
Seattle, WA ?98115 ? ? ??(206) 526-6317?? main reception
Chris.Barker at noaa.gov
Received on Thu Sep 17 2015 - 04:12:06 BST
