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Ticket | Resolution | Summary | Owner | Reporter |
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#149 | fixed | correction of standard name in example 7.3 | davidhassell | taylor13 |
Description |
In example 7.3 ("Cell areas for a spherical geodesic grid") the standard_name for the area of the grid cell is given as "area", which is not in the current standard_name table. The correct standard_name for this variable is "cell_area", so a correction of this defect should be made. |
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#148 | fixed | New cell_methods: mabs/mibs/mebs | davidhassell | zender |
Description |
1. TitleAdd absolute value statistics to cell methods 2. ModeratorDavid Hassell 3. RequirementThe statistics mabs/mibs/mebs stand for "Maximum absolute value", "Minimum absolute value", and "Mean absolute value", respectively. They are similar to max/min/mean statistics, and they can be useful in characterizing data when one wants positive-definite metrics. mebs (unlike mean) does not allow positive and negative values to compensate eachother. Unlike rms, mebs not does weight outliers quadratically. NCO implements mabs/mibs/mebs as fundamental statistics (like max/min/mean), and annotates the cell_methods attribute of variables reduced by these statistics with the strings "maximum_absolute_value", "minimum_absolute_value", "mean_absolute_value". 4. Initial Statement of Technical ProposalThis recommendation could be implemented in CF by inserting the following lines into Table E.1. Cell Methods cell_methods: Units: Description: maximum_absolute_value u Maximum absolute value minimum_absolute_value u Minimum absolute value mean_absolute_value u Mean absolute value 5. BenefitsThis would improve the CF-compliance of fields processed by absolute-value statistics. 6. Status QuoThere is no standard CF terminology to describe absolute-value statistics so fields analyzed with these methods may have missing, erroneous, or non-standard cell_methods for this stage of processing. Unless the statistics were computed with NCO which has implemented the proposed cell_methods since February, 2015. |
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#147 | fixed | clarification of standard and correction of conformance doc: formula_terms | cf-conventions@… | taylor13 |
Description |
Based on a statement appearing in the conformance document, the CF checker raises an error when the formula_terms attribute is attached to a variable other than a coordinate variable. It turns out that formula_terms are essential for interpreting the bounds on dimensionless vertical coordinates, so formula_terms should be provided whenever a variable with one of the standard_names listed in Appendix C appears in a file. The formula terms associated with bounds are needed, for example, to compute the pressure-thickness of model atmospheric layers (needed to compute the grid cell mass). To correct this defect (and remove any impression that the formula_terms can *only* be attached to coordinate variables (as formally defined by the NUG), I propose:
A final note: In CMIP5 (and as planned for CMIP6), formula_terms are defined for vertical dimensionless coordinates and also for the bounds on those coordinates. If the CF checker is modified as suggested above, it will no longer raise an error in checking CMIP output files. |