Changes between Initial Version and Version 1 of Ticket #153


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Timestamp:
11/03/16 06:56:42 (2 years ago)
Author:
martin.juckes
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  • Ticket #153 – Description

    initial v1  
    1 This ticket is still under constrcution ......
    21
    32A significant number of standard names contain, in their definitions, explicit specifications for additional required metadata. For instance, if the standard_name is "region" then there are constraints on the allowed values of the data variable. The standard name descriptions cannot include examples or markup, and the specification of the rules is not as clear as in the convention text. It also appears that the rules are not checked by the CF checker (at least not the few that I have looked at in detail) and I think the best way to get consistent checking would be to first create a well structured summary of these rules in the conventions document.
     
    54The specific proposal is add a new Appendix which lists the rules with examples where appropriate.
    65
     6It will take some time to complete the list. I propose that we add a provisional list, after agreeing the format and approach, and work towards completion later.
     7
    78= Appendix D: Rules associated with standard names =
    89
    910Some standard names bring additional constraints on the meta-data and/or data values of the variables they are associated with. This appendix list such names, grouped according to the types of constraint, and provides usage examples where needed.
    1011
     12== Required Coordinates ==
     13
     14A common constraint involves the requirement that a particular coordinate or set of coordinates be present.
     15 
    1116The following table lists the rules and associated standard names. An explanation of each rule follows below.
    1217
    13 |||| =Rule= || =Standard Name(s)= ||
    14 || 1 || Area Fraction || area_fraction ||
    15 || 2 || Lifted from || atmosphere_convective_available_potential_energy, atmosphere_convective_inhibition, atmosphere_level_of_free_convection, atmosphere_lifting_condensation_level ||
    16 || 3 || Lifting range ||  temperature_difference_between_ambient_air_and_air_lifted_adiabatically ||
    17 ||    || to be completed || ||
     18||||= Rule =||= Description =||
     19||||    ||= ''Standard Name(s)'' =||
     20||||    ||= '''Required coordinate(s)''' =|| 
     21|| 1 || Area Fraction || The fractional area in a cell covered by a particulate area type. ||
     22|||| || ''area_fraction'' ||
     23|||| || '''area_type''' ||
     24|| 2 || Lifted from || Parameters defined in terms of lifting from a reference level ||
     25||||     ||''atmosphere_convective_available_potential_energy, atmosphere_convective_inhibition, atmosphere_level_of_free_convection, atmosphere_lifting_condensation_level'' ||
     26||||     || '''original_air_pressure_of_lifted_parcel''' ||
     27|| 3 || Lifting range || Parameter defined in terms of lifting through a specified range  ||
     28||||   || ''temperature_difference_between_ambient_air_and_air_lifted_adiabatically'' ||
     29||||   || '''original_air_pressure_of_lifted_parcel,final_air_pressure_of_lifted_parcel'''  ||
     30|| 4 || Radiances || For radiance variables a direction must be specified ||
     31||||  || ''downwelling_photosynthetic_photon_radiance_in_sea_water'' and others
     32||||  ||  '''zenith_angle''' ||
     33|| 5 || Reference state || Variables which depend on reference air temperature and humidity ||
     34||||   ||  ''mass_concentration_of_pm_*_ambient_aerosol_in_air,  mass_fraction_of_pm_*_ambient_aerosol_in_air'' ||
     35||||    ||  '''air_temperature, relative_humidity''' ||
     36|| 6 || Wavelength || Functions of wavelength ||
     37||||   ||  ''*_per_unit_wavelength_in_air'' ||
     38||||   ||   '''radiation_wavelength''' ||
    1839
    19 == Area fraction ==
     40In all cases, the structure follows the same pattern, illustrated by the following examples for case 1. Area Fraction:
    2041
    21   Variables with standard name area_fraction require a coordinate with standard name area_type;
    2242{{{
    2343   float cropcover(lat,lon);
    24       standard_name: area_fraction;
    25       coordinate: crop
     44      cropcover:standard_name = 'area_fraction';
     45      cropcover:coordinates =  'crop';
     46      cropcover:units = '1';
    2647   character crop(nchar);
    27       standard_name: area_type;
     48      crop:standard_name = 'area_type';
    2849   data:
    29       crop: 'crop';
     50      crop = 'crop';
    3051}}}
    3152
    32 == Lifted from ==
     53== Other rules ==
    3354
    34 atmosphere_lifting_condensation_level + 3 others: requires an original_air_pressure_of_lifted_parcel coordinate.
     55=== Quantities representing a layer average or sum ===
    3556
    36 == Lifting range ==
     57Many "layer" quantities require vertical coordinates with bounds.
     58* ''*_atmosphere_layer[_*]'';
     59* ''*_ocean_layer[_*]'';
     60* ''*_soil_layer[_*]'';
    3761
    38 == Quantities representing a layer average or sum ==
     62=== Variation of variables in sigma coordinates due to surface pressure change ===
     63 change_in_energy_content_of_atmosphere_layer_due_to_change_in_sigma_coordinate_wrt_surface_pressure: must have a vertical coordinate variable (axis=Z).
    3964
    40 Many "layer" quantities (e.g. dry_static_energy_content_of_atmosphere_layer): require vertical coordinate with bounds.
     65{{{
     66   float deltae(sig);
     67      deltae:standard_name = 'change_in_energy_content_of_atmosphere_layer_due_to_change_in_sigma_coordinate_wrt_surface_pressure';
     68      deltae:units = 'J m-2';
     69   float sig(sig);
     70      sig:axis = 'Z';
     71      sig:standard_name = 'atmosphere_sigma_coordinate';
     72      sig:bounds = 'sig_bnds';
     73      sig:units = '1';
     74   float sig_bnds(2,sig);  # required because of _atmosphere_layer
     75}}}
    4176
    42 == Variation of variables in sigma coordinates due to surface pressure change ==
    43  change_in_energy_content_of_atmosphere_layer_due_to_change_in_sigma_coordinate_wrt_surface_pressure: must have a vertical coordinate variable (axis=Z)
     77=== Temporal change ===
    4478
    45 == Time rate of change or displacement over time ==
     79Time rate of change or displacement over time require bounds on time coordinate:
     80 * ''change_over_time_*'';
     81 * ''*_displacement'';
    4682
    47 change_over_time_... and .._displacement: require bounds on time coordinate
     83----
    4884
    49 == Radiances ==
     85= Comments for discussion =
    5086
    51 downwelling_photosynthetic_photon_radiance_in_sea_water and other radiance variables: direction must be specified, e.g. with coordinate of "zenith_angle".
    52 
    53 == Variables which depend on reference air temperature and humidity ==
    54 
    55 mass_concentration_of_pm..._ambient_aerosol_in_air (and mass_fraction_of_pm..): require air_temperature and relative_humidity
    56 
    57 == Functions of wavelength ==
    58 
    59 isotropic_radiance_per_unit_wavelength_in_air (and other per_unit_wavelength varables): the definition is slightly ambiguous with the sentence  "A coordinate variable for radiation wavelength should be given the standard name radiation_wavelength" which, taken literally, means the use of a wavelength coordinate is optional: should it be "A coordinate variable for radiation wavelength should be given with the standard name radiation_wavelength", making the wavelength coordinate required?
    60 
     87In some cases the wording of standard_name definitions could be interpreted as a recommendation or suggestion rather than a requirement. If some of these are intended only as suggestions, that should be flagged.