Jim:
I agree with Chris. I would say the value calculated is an average of the cell. However, I think the complete syntax should be
cell_methods = "time: mean area: mean"
v/r
rh
----------------------------------------
From: "Chris Barker" <chris.barker at noaa.gov>
Sent: Thursday, November 21, 2013 5:00 PM
To: "Jim Biard" <jbiard at cicsnc.org>
Cc: "cf-metadata at cgd.ucar.edu" <cf-metadata at cgd.ucar.edu>
Subject: Re: [CF-metadata] cell_methods question
On Thu, Nov 21, 2013 at 1:03 PM, Jim Biard <jbiard at cicsnc.org> wrote:
The data is a global grid that has a value for every cell. The values were obtained by fitting a function to a set of irregularly spaced points and then sampling the function at the center of each cell.
got it -- sorry for the confusion, that is pretty much what you said the first time...
But: at a theoretical level you have a continuous field -- it was sampled at irregular discrete points. You then constructed a regular grid of points by fitting the sample points. So the values you have for each cell is an estimate of the value at the point it was computed. Do its lat-lon is that point, i.e. the lat-lon of the center of the cell.
If that's essentially a point value, then you're done. If that's say, a average of the cell, then you would want cell_method: mean
But the original points are irrelevant to the this. Of course, you probably want to express that these are results from an interpolation, but I don't know that there's a way to do that in CF -- but it's not cell_methods.
-Chris
Jim
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On Nov 21, 2013, at 3:59 PM, Chris Barker <Chris.Barker at noaa.gov> wrote:
On Thu, Nov 21, 2013 at 9:05 AM, Jim Biard <jbiard at cicsnc.org> wrote:
I have a variable that contains a time average of gridded temperature measurements. The grid is produced by a fit of irregularly-spaced point data (weather stations), and any given cell might not contain an actual measurement point. I understand that I should have a cell_method of "time: mean" for the time axis, but what should I do for the lat/lon dimensions?
Maybe I misunderstand your data, but I think that for this purpose, the "cell" is only in the time dimension -- it is still point data in the lat/lon dimensions. So each value of a given variable is still associated with a single lat and long. So you do the same thing as usual for that.
HTH, -Chris
Grace and peace,
Jim
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