[CF-metadata] Sea water velocity

From: Jonathan Gregory <j.m.gregory>
Date: Tue, 6 Oct 2009 08:57:30 +0100

Dear St?phane

> The radial direction is the direction the radar is looking at (in
> angular degrees, clockwise, with 0=north).

Ah, I see now. I was confused because it seemed to me that "radial" was
itself a direction (rather than azimuthal). Perhaps we could call it
  direction_of_radial_vector_away_from_instrument
which would correspond to
  radial_sea_water_velocity_away_from_instrument
that we have agreed. In CF names, "direction" means what you say above.

> I noticed those chapters, but it was not clear to me that standard
> error is the same as the approximation error.
> I thought that standard error refers to statistics.

standard_error here means statistic uncertainty or systematic (measurement)
uncertainty. Does that meet the need?

> >Possibly
> >you could do this by labelling the mask as a status_flag variable (App C).
> >A more usual way to supply the valid data mask is of course to use missing
> >data values in the data variable.
> >
> I agree with the status_flag variable, but it applies to several data
> variables. For example, I have only
> one flag variable witch applies to both northward and eastward sea water
> velocity varaibles. What is
> the correct standard name for such a status_flag variable ?

If the purpose of the variable is to indicate missing or non-missing, why do
you need to store it in a separate variable, rather than indicating it with
missing data values in the data variables?

That doesn't answer your question, though. I understand there might be a need
to share ancillary data among several data variables with different standard
names. I suppose that there is nothing to prevent a variable with standard_name
"X" having an ancillary_variables attribute which points to a variable with
standard name "Y status_flag", for instance. Perhaps we should review this
convention.

Best wishes

Jonathan
Received on Tue Oct 06 2009 - 01:57:30 BST