Well, yes, the last sentence can be simplified.
It is a copy/paste/adaptation of the sentence describing
upward_air_velocity, where the 3D aspect is important. In our present
case, I let readers/reviewers judge on that point.
For your information, my current need is for airborne measurements,
where vertical velocity cannot be assumed null.
On ships, I would say that the assumption "vertical velocity is 0"
depends on the time scale. If you are doing eddy correlation
computation, and store your high-freq data in a netcdf/CF file, you'll
deal with non-null instantaneous vertical motion. Probably not a
mainstream use of netcdf/CF, though.
Bruno.
Le mardi 30 août 2011 à 10:36 -0400, Nan Galbraith a écrit :
> These look good, and are certainly needed.
>
> Just one question about the last line of each of the definitions,
> referring to the 3D platform velocity. On ships, there's often only
> a 2D vector, I suppose the vertical velocity is presumed to be 0.
>
> Would it be preferable to not specifically mention 3D, and just say
> "the eastward (or northward/vertical) component of the platform
> velocity vector" to make this "fit" 2D ship tracks as well?
>
> Thanks - Nan
>
>
> On 8/30/11 10:12 AM, Bruno PIGUET wrote:
> > Dear all,
> >
> > I would like to request the creation of new standard names for the
> > local geographic components of the platform_speed_wrt_ground.
> >
> > Following the already existing definition of speed, velocity, and the
> > naming scheme for the wind component (eastward_wind, northward_wind,
> > upward_air_velocity), I propose :
> >
> > - platform_northward_velocity_wrt_ground
> > "wrt" means with respect to. Standard names for platform describe the
> > motion and orientation of the vehicle from which observations are made
> > e.g. aeroplane or ship. A velocity is a vector quantity. The platform
> > velocity with respect to ground is relative to the solid Earth beneath
> > it i.e. the sea floor for a ship. It is often called the "ground speed"
> > of the platform. "Northward" indicates a vector component which is
> > positive when directed northward (negative southward).
> > Platform_northward_velocity_wrt_ground is the northward component of the
> > 3D platform velocity vector.
> >
> > - platform_eastward_velocity_wrt_ground
> > "wrt" means with respect to. Standard names for platform describe the
> > motion and orientation of the vehicle from which observations are made
> > e.g. aeroplane or ship. A velocity is a vector quantity. The platform
> > velocity with respect to ground is relative to the solid Earth beneath
> > it i.e. the sea floor for a ship. It is often called the "ground speed"
> > of the platform. "Eastward" indicates a vector component which is
> > positive when directed eastward (negative westward).
> > Platform_upward_velocity_wrt_ground is the eastward component of the 3D
> > platform velocity vector.
> >
> > - platform_upward_velocity_wrt_ground
> > "wrt" means with respect to. Standard names for platform describe the
> > motion and orientation of the vehicle from which observations are made
> > e.g. aeroplane or ship. A velocity is a vector quantity. The platform
> > velocity with respect to ground is relative to the solid Earth beneath
> > it i.e. the sea floor for a ship. It is often called the "ground speed"
> > of the platform. "Upward" indicates a vector component which is positive
> > when directed upward (negative downward).
> > Platform_upward_velocity_wrt_ground is the vertical component of the 3D
> > platform velocity vector.
> >
> >
> > Bruno.
> >
> >
> > _______________________________________________
> > CF-metadata mailing list
> > [email protected]
> > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>
>
--
Bruno PIGUET
Mèl : [email protected] | GAME : URA CNRS & METEO-FRANCE
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