On 7/26/2011 4:24 AM, Jonathan Gregory wrote:
Dear all
For datasets which are intended for analysis by end-users I think it would be
undesirable to remove the requirement of providing explicit lat and lon
coords even if a grid_mapping is provided. I think it is unrealistic to expect
all
Hi,
while trying to translate weather-model-data for the GIS community, and
as such translating CF-parameters to proj4 parameters, I recognized some
things:
* The latitude-longitude field does not give any additional information
to the grid-mapping. In fact, in most cases the
Heiko,
Comments below.
On Aug 1, 2011, at 2:56 AM, Heiko Klein wrote:
Hi,
while trying to translate weather-model-data for the GIS community, and as
such translating CF-parameters to proj4 parameters, I recognized some things:
* The latitude-longitude field does not give any
Dear Dave
I sympathise with your concerns about the consequences of missing datums but
I don't think CF can help a lot.
Are there any arguments against CF recommending a standard datum assumption
when intersecting data without a datum specified with data that does have a
datum specified?
I
Dear Jonathan, All,
Coming from the perspective of a geographer, for CF to be a convention whereby
people can provide accurate and complete metadata for their data. Datum
specification would be required.
I understand that the normal practice in the climate science community is to
throw out
Hi all:
If I understand the situation, a GCM, whether global or regional, always
has a datum. In the simple case, its just the radius of a spherical
earth. However, for current global models its typical that this datum
doesnt affect anything (presumably as long as its within the typical
Also, I think datum and precision are completely different things.
Specifying or not specifying datum does not say anything about
precision. GCM or any model for that matter if it uses data with known
datum as input, I would expect an output with known datum. Regardless of
the model resolution
Without the grid_mapping, the lat and lon still make sense in the common case
(and original CF case) of GCM data, and in many other cases, the intended
usage of the data does not require precision about the figure of the Earth.
Although this metadata could be valuable if it can be defined, I
Jonathan and Karl,
I don't disagree with the GCM examples or lack of model resolution being talked
about here, I just don't think that is the only argument.
There are cases, like downscaled climate projections, reanalysis products, or
radar indicated rainfall, where a datum is critical to
Dear all
For datasets which are intended for analysis by end-users I think it would be
undesirable to remove the requirement of providing explicit lat and lon
coords even if a grid_mapping is provided. I think it is unrealistic to expect
all software which someone might use to analyse netCDF
2011 08:20
To: John Caron
Cc: cf-metadata@cgd.ucar.edu
Subject: Re: [CF-metadata] the need to store lat/lon coordinates in a CF
metadata compliant netCDF file
An observation...
It seems implied that in CF lat/long coordinate values on their own are viewed
as authoritative. I would argue against
All,
Several controversial points have been raised already in this
discussion. It seems clear that there are multiple (valid)
perspectives. My sense is that the question we need to answer is
_Under what circumstances_ are lat/long coordinates mandatory?, rather
than a simple yes or no.
I agree with a lot of points here. I think that grid_mappings can never
be comprehensive; I think as well that at some point it will be
prohibitive to include coordinate informtion in every file that needs
it: this is already redundant and potentially introduces two new 2D
fields alongside every
John,
On 07/11/2011 03:17 PM, John Caron wrote:
On 7/11/2011 2:55 PM, Alexander Pletzer wrote:
All,
The host file and the mosaic file allow users to store coordinate
data in external files. Section 10.6 in
https://ice.txcorp.com/trac/modave/wiki/CFProposalGridspec describes
this. The host
Hi All,
Section 4.1 says:
(http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.5/cf-conventions.html#coordinate-types)
/Coordinate types other than latitude, longitude, vertical, and
time _*are allowed*_. To identify generic spatial coordinates we
recommend that the |axis| attribute
On 6/30/2011 1:26 PM, Randy Horne wrote:
Paragraph 5.6 Coordinate Reference Systems, Grid
Mappings, and Projections, first sentence:
When the coordinate variables for a horizontal grid are not longitude and
latitude, it is required that the true latitude and longitude coordinates be
supplied
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