Thanks, Jonathan - This makes perfect sense now. Instruments may output
vertical velocity because the manufacturer doesn't know the orientation of
the deployment in advance. It seems fine for the data writer to chose the
appropriate name when publishing the data in CF.
Thanks again - Nan
On 3/1/16 10:42 AM, Jonathan Gregory wrote:
Dear Nan
Including upward/downward in the standard names of vertical components of
vectors was a design decision when we started on the compiling the table,
as with northward/southward, eastward/westward and any quantity which has
a direction associated with it. Yes, there are other pairs where both senses
have names. The reason is to make sure the sign convention is recorded. If
it was a separate attribute, there's a reasonable chance it would not be
included, or might be wrong.
It sounds like you have a different use-case, with a sensor that measures a
velocity component which isn't strictly vertical. We could give that a
different name (i.e. component parallel to the instrument orientation, with
again the need to indicate the sign convention somehow).
Best wishes
Jonathan
----- Forwarded message from Nan Galbraith <[email protected]> -----
Date: Tue, 1 Mar 2016 10:31:25 -0500
From: Nan Galbraith <[email protected]>
To: [email protected]
Subject: Re: [CF-metadata] New standard_name: downward_air_velocity
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:38.0)
Gecko/20100101 Thunderbird/38.6.0
I agree, it's consistent, and may as well be added.
That said, I'm not sure why we don't use 'vertical' for the vertical
component of
all these 3d velocity vectors, and then recommend an attribute that
would specify
the direction (up- or down-ward). I didn't have time to check
whether we have
any standard names that exist in both the upward and downward form ( I'm
not really sure if that would be a problem, any way, but it seems
like it might be).
The reason this is important in my data is that some current meters
and profilers
output a vertical velocity where the direction depends on the
orientation of the
instrument. The vertical velocity is also a measure of measurement
quality in those
data sets, since excessive vertical values usually indicate an error
in the other
vectors.
Cheers - Nan
On 2/26/16 2:46 PM, Jonathan Gregory wrote:
Dear Ken
That looks good to me - clearly consistent with existing names.
Best wishes
Jonathan
----- Forwarded message from "Kehoe, Kenneth E." <[email protected]> -----
Date: Thu, 25 Feb 2016 20:31:31 +0000
From: "Kehoe, Kenneth E." <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [CF-metadata] New standard_name: downward_air_velocity
CF,
Can we add downward_air_velocity to be the counter to the existing
upward_air_velocity.
Definition = A velocity is a vector quantity. “Downward" indicates a vector
component which is positive when directed downward (negative upward). Downward air
velocity is the vertical component of the 3D air velocity vector.
Thanks,
Ken
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* Nan Galbraith Information Systems Specialist *
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