Folks:
We have done some more thinking about how to capture the resolution of gridded observation data (this is a more accurate term than used in previous posts - imagery) using a to-be-determined CF convention. Note that a key underlying assumption here is that the gridded data has a homogeneous sampling interval.
Originally, I thought a cell_method related approach made sense, but the resolution of elements in a data variable is not pertinent to the functional intent of cell methods.
A suggestion from the board thought that a new coordinate type could be defined to provide this capability. The problem with this is that data resolution is not a coordinate, but, rather, a size characteristic of each element in the data variable containing the gridded observation data.
This brings you back to cells (1st sentence of chapter 7 - When gridded data does not represent the point values of a field but instead represents some characteristic of the field within cells of finite "volume," a complete description of the variable should include metadata that describes the domain or extent of each cell, and ....)
There are a variety of options available to support this including an additional syntax for cell boundaries or cell measures, or a new "cell resolution" that may only be associated with observation data.
The core of any of these approaches would be the specification of a numeric resolution with its units. Using the existing cell "(interval: value unit)" as a model, a GOES-R 2 km at nadir gridded product would have an attribute component that looks like:
"(resolution: y = 0.000056 rad x = 0.000056 rad)" if it were part of a broader category (i.e. "bounds:" or "cell_measures"), or
"resolution: y = 0.000056 rad x = 0.000056 rad", if it was not associated with cell bounds or measures. Note that the syntax to capture the resolution would need to be flexible to handle the different cell shapes for observation data. "y" and "x" in these examples are intended to represent the spatial coordinate variables.
Comments appreciated !
very respectfully,
randy
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Received on Thu May 09 2013 - 07:56:20 BST
