Thanks all - I can certainly see the convenience value in including
the lat/lon arrays, but it is frustrating that some tools will reject
a dataset because of the absence of mandatory fields that they don't
need! Still, you have provided many valid arguments for retaining the
arrays and it's good
A few more cents:
1. Its more powerful for the client to know the projection transformation than
to know only the 2D lat/lon values. For that reason I always encourage
providers to include the projection info. When the client doesnt know what to
do with the projection info, having the 2D lat/l
Hi Jon,
In our experience they are very useful coordinate variables. Allowing a
simple and quick lookup without having to perform any calculations. For
example, cdms allows you to say:
>>> print myvar.getLatitude()
52.4555
If the data provider knows the lats and lons at write time it is fa
FWIW I've heard the same opinion from physical oceanographers
(probably the same ones!) that salinity has no units. I.e. that one
says "the salinity is 35", not "the salinity is 35psu". I interpret
this as meaning that the unit is actually part of the definition of
what salinity is (i.e. if it's
[with a small correction embedded in "**", because I know our community
will point it out if I don't]
Hi Jon,
Assuming I've understood your situation ...
First to restate the party line: The philosophy of CF has always been
that the coordinate systems be self-describing without the applicati
Hi Jon,
Assuming I've understood your situation ...
First to restate the party line: The philosophy of CF has always been
that the coordinate systems be self-describing without the application
needing to know the specific algorithms used to calculate coordinates
(from the name of the project
Thanks for the confirmation Don. This seems very odd indeed - if the
source data don't contain the (real) lon and lat coordinates then it's
quite onerous (and quite pointless) to do so in a convenient fashion
(it would generally involve re-writing the headers, or using some long
and ugly NcML). P
John-
I believe for all grid_mappings that lat/lon are required even though
the grid mapping defines the transformations necessary. I think it is
redundant in all cases, not just for the rotated lat/lon.
Don
Jon Blower wrote:
Dear all,
We have some data that use a rotated pole grid. The
Dear all,
We have some data that use a rotated pole grid. The CF convention for
describing this is here:
http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#id2985006.
Are the 2D lon and lat variables in this example really necessary?
They would seem to be redundant as thei
Dear Russ
I think it's a good development for udunits to support logarithmic units.
In CF standard names, however, we have taken the approach of stating the
reference level as part of the definition of the quantity, possibly allowing
it to be specified alternatively in a scalar coordinate variable
Jonathan,
> The intention of recording the units as 1e-3 (dimensionless) was to
> suggest a canonical unit of PSU i.e. approximately the same as parts
> per thousand. However, this is unclear and therefore
> unsatisfactory. We have discussed this before, in fact, and I believe
> we have decided i
to throw in an oceanographers viewpoint...
measured salinity has no units - it is determined from conductivity
and has no relationship to ppt, ppm psu or any other unit.
10-3 seems very dangerous (and equally wrong)
the only 'units' used recently (officially) are to state 'pss78' to
define
Dear All,
Might be worth looking at
http://www.oceanographers.net/forums/showthread.php?t=902
Cheers, Roy.
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Dear Roy
> The reason I'm resurrecting this discussion is that we came under strong
> pressure from a group of physical oceanographers to use 'dimensionless' with
> no scaling factor instead of PSU for salinity. I was raising the issue on
> the list to see how widespread this opinion was.
Yes
Hello Jonathan,
The reason I'm resurrecting this discussion is that we came under strong
pressure from a group of physical oceanographers to use 'dimensionless' with no
scaling factor instead of PSU for salinity. I was raising the issue on the
list to see how widespread this opinion was.
Chee
Dear Roy and Alison
The intention of recording the units as 1e-3 (dimensionless) was to suggest
a canonical unit of PSU i.e. approximately the same as parts per thousand.
However, this is unclear and therefore unsatisfactory. We have discussed this
before, in fact, and I believe we have decided in
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