Jonathan,
So, I?ve got a broader question. We have a case in hand with trajectory data for a physically extensive weather system. Two data variables are the mean longitude and latitude of the system, which we are treating as the auxiliary coordinate variables. Other data variables contain measurements such as maximum latitude at the mean longitude, etc. Are cell_methods applicable in this case? There is no grid, so the cell would be the area covered by the system, and the extents of this area are not described.
Grace and peace,
Jim
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On Feb 28, 2014, at 1:34 PM, Jonathan Gregory <j.m.gregory at reading.ac.uk> wrote:
> Dear Randy
>
> I think the answer is Yes and No! Only a data variable can have cell_methods,
> but there is no prohibition on referring to a data variable as an aux coord var
> by pointing to it from the coordinates attribute of another data variable.
> So the air_pressure variable could be a data variable with an appropriate
> cell_methods attribute, which would take the form "PIXEL: median" where PIXEL
> is the name of some dimension which was collapsed to calculate the median.
> Maybe this dimension does not exist, though? In that case I think it might
> make sense to put "area: median". This would mean the median of all the values
> within the area of that cell.
>
> Cheers
>
> Jonathan
>
> ----- Forwarded message from "rhorne at excaliburlabs.com" <rhorne at excaliburlabs.com> -----
>
>> From: "rhorne at excaliburlabs.com" <rhorne at excaliburlabs.com>
>> To: cf-metadata at cgd.ucar.edu
>> Date: Thu, 27 Feb 2014 11:30:02 -0500
>> Subject: [CF-metadata] can a cell method be an attribute of an auxiliary
>> coordinate variable ?
>>
>>
>> Dear All:
>>
>> i have a question ....
>>
>> We have a product containing an array of wind vectors (discrete sampling
>> geometry of type point) all derived from consecutive scenes of hyper
>> spectral imagery.
>>
>> One of the auxiliary coordinate variables is the air pressure. This air
>> pressure is the median value of the imagery pixels used to derive the wind
>> vector using a pattern recognition algorithm.
>>
>> There are no specific coordinates for the pixels that were used to derive
>> the wind vector, but it would be useful to identify that the air pressure
>> associated with the wind vector is a median value.
>>
>> Does it make sense to do the following in the specification of the air
>> pressure auxiliary coordinate variable ?
>>
>> float pressure (number_of_wind_vectors);
>>
>> standard_name = "air_pressure"
>>
>> cell_methods = "air_pressure: median"
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