Clarify some formula terms definitions #304
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enhancement
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davidhassell
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I've changed my mind about "For I think that it's OK for them to have different units of length (e.g. 'm' and 'km'), and it's up to the user to do any conversions. This is how it is in the rest of CF. I shall update the PR accordingly. |
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I support these proposed changes. @davidhassell : do you know anyone who has actually written a file based on these coordinates? If so, perhaps we could ask them (or anyone who is really familiar with the coordinates) to check that the CF descriptions are correct. |
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Thanks, @taylor13. I don't know of any such data providers for the more involved formulas (such as |
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Hello, Are we OK to merge this PR, do you think? The proposed changes in #305 come from a dimensional analysis resulting from writing software can create the non-parametric vertical coordinates from formula terms. We've not heard about about any checks on the correctness of the formulae themselves, but I think that that could be raised as a new issue. Thanks |
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Yes, I think it's OK, thanks. |
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I agree. It's o.k. |
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Thanks @taylor13 and @JonathanGregory, I shall merge shortly (which will also close cf-convention/vocabularies#101). |
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* added example 6.1.2 to the list of examples; fixed cf-convention#284 * updated changes in history.adoc * removed fourth lines of third table in sect 9.3.1; fixed cf-convention#288 * updated history * Bring conformance doc in line with clarification to use of region names/area_types to allow use of flag_values and flag_meanings as per discussion in cf-convention#198 * Add support for variables of type string to conformance doc. See issue cf-conventions#139 * Revert "Bring conformance doc in line with clarification to use of region names/area_types to allow use of flag_values and flag_meanings as per discussion in cf-convention#198" This reverts commit f754457. * first draft of section 5.8 * format typo * rewording * rewording * rewording * New 'Do' Use value, and 'dimensions' entry * Domain construct * rewording * rewording * rewording * formatting of computed_standard_name entry * rewording * rewording * rewording * top-level * rewording * move fig 3 * rewording * span * rewording * data * rewording * rewording * rewording * conformance * recommended attributes * typo * dimensions * dimensions * format * typo * domain independence * domain optional * format * format * format * format * empty dimensions * long_name * UML * Update ch01.adoc * Update history.adoc * Add static assets to HTML check build * Add static assets to Travis upload job * Fix order of i/j in lon/lat bnds figure correct indices of neighbour cells in @d case * update/correct order of indices i/j in Fig 2 (2D lon/lat bounds) * update/correct order of indices i/j in caption of Fig 2 * rename "figure 1" to "figure 3" in Appendix i * correct indices of neighbour cells in @d case * update history Figures are generated from: https://github.com/neumannd/cell_bounds_figures_for_cf_conventions * updates arising from cf-convention#301 up to 2020-09-28 * correct label for 1.2 * format correction * reword empty dimensions example * comma * example links * long_name * formatting * missing 'construct' * term units * term units * standard names * typo * units conformance requirement * remove requirement for identical units * Copyedit * fixed typos * History * more text following 2020-11-27 discussions * bounds * tidy * tidy * tidy * tidy * reproducability * offset * indices * indices * indices * super * tie_point_dimension (1) * tie_point_dimension (2) * tie_point_dimension (3) * tie_point_dimension (4) * tie point * tie_point_dimension (5) * corrected interpolation_configuration description * zone/area rewording * zone/area rewording * multiple mappings * multiple mappings * multiple mappings * typos and some minor rewording suggestions * format * spell check * markup style * example formatting * example formatting * example formatting * example formatting * minor typesetting * interpolation_parameters * interpolation parameters variable dimensions * interpolation parameters variable dimensions * non-standard provision * interpolation parameters variable dimensions * captions, cdl * tidy * minumum size of interpolation zones * Appendix A attributes * interpolation -> sampling * Conformance - first draft * 2nd draft: better descriptions of allowed dimensions * typos * Correct 'is list' to 'is a list' * history cf-convention#304 * check on interpolation zone dimension size * Clarification of the handling of leap seconds This is the suggested initial wording from cf-convention#313 as authored by @JonathanGregory. * leap seconds: added the word "count" in some places The purpose of this change is to slightly highlight the difference between when seconds are used within the coordinate value for counting and the seconds which are part of the date-time. * leap seconds: minor wording extension * leap seconds: added reference to cf-convention#313 to history.adoc * add myself to the end of the list of additional authors * leap seconds: updated conformance text This change excludes values larger or equal to 60 for seconds in reference date-times in time unit attributes. Additionally, the reference time has been changed to reference date-time to agree with the wording in the proposed conventions text. * leap seconds: small rewording as discussed with @JonathanGregory Reasoning: counting may be associated with integral numbers, which is was not intended. We still like the idea of a little more separation between seconds as a unit of the value and seconds as in the date-times. * replace date-time with date/time * conformance changes for new interpolation variable * conformance changes for new interpolation variable * conformance changes for new interpolation variable * conformance changes for new interpolation variable * appendix A changes for new interpolation variable * appendix A changes for new interpolation variable * lat lon tie point definition * spelling * URI -> URL * lower resolution -> sampled * Use on domain variable * typo * Move 'interpolation dimension' definition to first occurence * Minor re-wording * Fix cross-reference * Re-wording * typesetting * tie point index re-wording * Rotation of interpolation axes for two dimensional methods and mino corrections * terminology: interpolation variable and tie point variable * typo * examples in toc * Replace expression for gsqr with equivalent, but numerically more accurate version * Update authors * Update history * Rename attribute tie_points to coordinate_interpolation (Change 2) * Reword section Interpolation and Non-Interpolation Dimensions (Cahnge 10) * Rename tie_point_dimensions attribute to tie_point_mapping (Change 2) * Change term 'tie point variable' to 'tie point coordinate variable' (Change 4) * Reword first paragraph of Section 8 (Change 6) * Remove sentence "This form of compression may also be..." (Change 7) * Update sentence: "A single interpolation dimension may be associated..." (Change 9) * Reword section "Interpolation and non-interpolation dimension" (Change 10) * Improve sentence "An interpolation zone must span at least two points..." (Change 11) * Correct sentence "....must be a subset of zero or more of the ..." (Change 12) * Reword text about the dimensions of interpolation parameter (Change 13) * Improve sentence "The bounds of a tie point must be the same..." (Change 14) * Reduce number of data variables in Example 8.5 (Change 16) * Rename "terms to continuous area" and "interpolation subarea" (Change 5) * Improve wording of "An interpolation subarea must span..." (Change 11) * Remove paragraph "The same interpolation variable may be multiply mapped ...." no longer relevant * Rename terms to: subsampled dimension, interpolated dimension and non-interpolated dimension * Combine the tie_point_dimensions and tie_point_indices attributes (Change 1) * Update figures to match new terms * Improve description of non-overlapping interpolation subareas * Improve description of non-overlapping interpolation subareas * Update Example 8.6 to correctly specify one dimension interpolation for X and Y * Improve wording of Tie Point Index Mapping (Change 8) * Clarify interpolation subarea size * Clarify dimensions in Figure 2 * Add new section 8.3.9, "Computational Precision" * Combine the tie_point_dimensions and tie_point_indices attributes (Change 1) * Remove paragraph "A single interpolated dimension may be associated with multiple ...." no longer relevant * Update ch08.adoc Co-authored-by: David Hassell <[email protected]> * Update ch08.adoc Co-authored-by: David Hassell <[email protected]> * Update ch08.adoc Co-authored-by: David Hassell <[email protected]> * Update ch08.adoc Co-authored-by: David Hassell <[email protected]> * Change sampl... to subsampl... * Rewrite section Interpolation of Cell Boundaries (Change 15) * Constrain interpolation parameters to support bounds interpolation * Update <<link>> names and figure names to new terms * Require tie points to be numeric type and have no missing values * Update Appendix J with new terms and names * Correct spelling mistake in Appendix J * Correct numbering mistake in Appendix J * Change "iz" (interpolation zone) to "is" (interpolation subarea) in App J (Change 3) * Correct "target dimension" to "interpolated dimension" (Change 17) * Introduce section numbering and remove table captions in Appendix J * Include interpolation argument s in figure 1 and 2 * Move Figure 1 and 2 in Appendix J futher down * State tht for linear interpolation, the coordinates of the interpolated points are evenly spaced. * Change "equivalently" to "similarly" in explanation of s1 and s2 in App J * Rename cofficeint "c" to "w" in Appendix J to avoid confusion with point C * Move "Common Conversions and Formulas" in front of "Interpolation Methods" in Appendix J * Add "s" to "each of the interpolated dimension" in Appendix J * Minor wording improvements arising from review * Conformance for bounds tie points * computational_precision conformance Co-authored-by: Daniel Neumann <[email protected]> Co-authored-by: Rosalyn Hatcher <[email protected]> Co-authored-by: JonathanGregory <[email protected]> Co-authored-by: Daniel Lee <[email protected]> Co-authored-by: Daniel Lee <[email protected]> Co-authored-by: David Blodgett <[email protected]> Co-authored-by: AndersMS <[email protected]> Co-authored-by: Tobias Kölling <[email protected]> Co-authored-by: Tobias Kölling <[email protected]>
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Clarify some formula terms definitions
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Requirement Summary
The formulas for computing non-parametric vertical coordinates are in general well defined, but in some cases the allowed units and standard names of some of the formula terms are not stated.
It is possible to infer the units by a dimensional analysis of the formula, and to ascertain that some terms require identical units to particular other terms. However, it would be better to state these requirements explicitly to assist data providers and anyone who writes software to carry out the computation.
The changes needed are:
For ocean_double_sigma_coordinate that
a,z1andz2must all have identical units of (any) length (to ensure that the tanh operand is correct).For ocean_s_coordinate that
aandbmust be dimensionless anddepth_cmust have units of length.For ocean_s_coordinate_g1 the
computed_standard_nameand standard names ofCanddepth_cneed defining.For ocean_s_coordinate_g2 the
computed_standard_nameand standard names ofCanddepth_cneed defining.The last two points are brought in from cf-convention/vocabularies#101
Technical Proposal Summary
For the relevant terms, a few lines are added to Appendix D: Parametric Vertical Coordinates.
The conformance document is updated to include a check on the units.
Benefits
As well bringing clarity to data providers and software writers, this change will allow the CF checker to check these items.
Status Quo
Everyone has work out what the units and standard names of these term should be, and the CF checker has no way of reporting any errors.
Associated pull request
PR #305
Detailed Proposal
See PR #305
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