On 8/11/2011 9:14 AM, Upendra Dadi wrote:
> Hi,
> I have a related question about "bounds" attribute. I often see
> regularly gridded latitude-longitude data which do not have "bounds"
> specified when probably they should. But they almost always have
> regularly spaced latitude and longitude values which are at the middle
> of each cell. CF checkers have no way to identify the problem since
> files are valid both ways even though CF implementations might
> interpret them differently (do they?). My question is what are the
> consequences of not having "bounds" for analysis operations that are
> commonly used in various models.
>
Hi Upendra,
The introduction to CF Chapter 4 states:
"If bounds are not provided, an application might reasonably assume
the gridpoints to be at the centers of the cells, but we do not
require that in this standard. "
Arguably this could/should be tightened up to say "If bounds are not
provided, applications should assume the gridpoints to be at the centers
of the cells. " in order to remove any ambiguity. Opinions whether
there might be any backwards compatibility issues from this change?
- Steve
> Upendra
>
>
> On 8/10/2011 8:31 AM, John Caron wrote:
>> On 8/8/2011 3:43 PM, Jim Biard wrote:
>>> Hi.
>>>
>>> I have a time series of monthly averaged values. I have an
>>> integer-valued time coordinate variable and an associated
>>> time_bounds variable. Is it correct to use the 15th of February and
>>> the 16th of all the other months for my time centers, or should I
>>> use the 16th of every month?
>>>
>>> Also, should I do anything differently if my data are climatological
>>> monthly averages (say, over 30 years of data)? And, in this case,
>>> should the time coordinate values be day numbers from the beginning
>>> of the 30-year time interval, the end of the time interval, or
>>> something else entirely?
>>>
>>> Grace and peace,
>>>
>>> Jim Biard
>>>
>>
>> At the moment, IMO the best that can be done in CF is to accurately
>> record the date range (using the bounds attribute). The coordinate
>> value should then be considered for labeling purposes only. Make a
>> one line description and put into the long_name attribute. Make sure
>> you have human readable documentation that explains whats going on in
>> detail, and add a global attribute that references it. Set up a
>> 24-hour hotline to answer questions, staffed by post-docs wearing
>> beepers. Ok, maybe not the last ;^)
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>
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Received on Thu Aug 11 2011 - 10:33:04 BST
