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saeon_netcdf_guidance [2022/07/11 14:24] – [Variable Attributes] lindsay | saeon_netcdf_guidance [2022/07/28 12:23] (current) – lindsay | ||
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Note: The // | Note: The // | ||
- | ==== Variable Attributes | + | === Variable Attributes === |
== Time coordinates == | == Time coordinates == | ||
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| long_name | “time” | A descriptive name that indicates a variable’s content. | | | long_name | “time” | A descriptive name that indicates a variable’s content. | | ||
| units | “seconds since 1970-01-01 00:00:00 UTC” | Use approved CF convention with approved UDUNITS obtained from CF standard name table. Please contact SAEON curation if help is required. | | | units | “seconds since 1970-01-01 00:00:00 UTC” | Use approved CF convention with approved UDUNITS obtained from CF standard name table. Please contact SAEON curation if help is required. | | ||
- | | calendar(CONDITIONAL) | “gregorian” | Calendar used for encoding time axes. See CF documentation for clarification. Default is " | + | | calendar (CONDITIONAL) | “gregorian” | Calendar used for encoding time axes. See CF documentation for clarification. Default is " |
- | | valid_min(RECOMMENDED) | “1530779700” | Smallest valid value of a variable. Should be of the same type as the variable type. | | + | | valid_min (RECOMMENDED) | “1530779700” | Smallest valid value of a variable. Should be of the same type as the variable type. | |
- | | valid_max(RECOMMENDED) | “1530791710” | Largest valid value of a variable. Should be of the same type as the variable type. | | + | | valid_max (RECOMMENDED) | “1530791710” | Largest valid value of a variable. Should be of the same type as the variable type. | |
| axis | “T” | Identifies the time coordinate. Set value of “T”. | | | axis | “T” | Identifies the time coordinate. Set value of “T”. | | ||
- | | comment(RECOMMENDED) | “....” | Miscellaneous information about the data, that cannot be described in any of the other available attributes. | | + | | comment (RECOMMENDED) | “....” | Miscellaneous information about the data, that cannot be described in any of the other available attributes. | |
== Horizontal coordinates == | == Horizontal coordinates == | ||
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| long_name | “latitude”or“longitude” | A descriptive name that indicates a variable’s content. | | | long_name | “latitude”or“longitude” | A descriptive name that indicates a variable’s content. | | ||
| units | “degrees_north” (LATITUDE)or “degrees_east” (LONGITUDE) | Use approved CF convention with approved UDUNITS obtained from CF standard name table. | | | units | “degrees_north” (LATITUDE)or “degrees_east” (LONGITUDE) | Use approved CF convention with approved UDUNITS obtained from CF standard name table. | | ||
- | | valid_min(RECOMMENDED) | “-34.678” (LATITUDE)or“26.012” (LONGITUDE) | Smallest valid value of a variable. Should be of the same type as the variable type. | | + | | valid_min (RECOMMENDED) | “-34.678” (LATITUDE)or“26.012” (LONGITUDE) | Smallest valid value of a variable. Should be of the same type as the variable type. | |
- | | valid_max(RECOMMENDED) | “-34.678” (LATITUDE)or“26.012” (LONGITUDE) | Largest valid value of a variable. Should be of the same type as the variable type. | | + | | valid_max (RECOMMENDED) | “-34.678” (LATITUDE)or“26.012” (LONGITUDE) | Largest valid value of a variable. Should be of the same type as the variable type. | |
| axis | “Y” (LATITUDE)or “X” (LONGITUDE) | Identifies the horizontal coordinate. Set values of “X” or “Y”. | | | axis | “Y” (LATITUDE)or “X” (LONGITUDE) | Identifies the horizontal coordinate. Set values of “X” or “Y”. | | ||
- | | comment(RECOMMENDED) | “....” | Miscellaneous information about the data, that cannot be described in any of the other available attributes. | | + | | comment (RECOMMENDED) | “....” | Miscellaneous information about the data, that cannot be described in any of the other available attributes. | |
+ | |||
+ | == Vertical coordinates == | ||
+ | |||
+ | Depth or height variables should be measured in SI units, most commonly “metres”. Pressure measurements should not be labelled as a depth or height variable, but as a separate parameter. | ||
+ | |||
+ | __Table 4. List of depth variable attributes for SAEON netCDF files__ | ||
+ | |||
+ | //All attributes are MANDATORY to include in your netCDF unless stated: CONDITIONAL= include these fields if the information exists, or RECOMMENDED = it is recommended to include these fields but not mandatory.// | ||
+ | |||
+ | | **Attribute** | **Example** | **Description** | | ||
+ | | standard_name | “depth” | A description of the variable’s content from the CF standard name table. | | ||
+ | | long_name | “depth” | A descriptive name that indicates a variable’s content. | | ||
+ | | units | “m” | Use approved CF convention with approved UDUNITS obtained from CF standard name table. | | ||
+ | | positive | “down” | The direction of increasing vertical coordinate values corresponding to a reference point. Either “up” or “down”. | | ||
+ | | valid_min (RECOMMENDED) | “10” | Smallest valid value of a variable. Should be of the same type as the variable type. | | ||
+ | | valid_max (RECOMMENDED) | “1256” | Largest valid value of a variable. Should be of the same type as the variable type. | | ||
+ | | axis | “Z” | Identifies the vertical coordinate. Set value of “Z”. | | ||
+ | | comment (RECOMMENDED) | “....” | Miscellaneous information about the data, that cannot be described in any of the other available attributes. | | ||
+ | |||
+ | == Geophysical parameters == | ||
+ | |||
+ | These variables contain the data collected by an instrument or sensor. | ||
+ | |||
+ | Note: For cases where a netCDF contains two sensors measuring the same variable it is important that these are easily differentiated, | ||
+ | |||
+ | __Table 5. List of geophysical parameter variable attributes for SAEON netCDF files__ | ||
+ | |||
+ | //All attributes are MANDATORY to include in your netCDF unless stated: CONDITIONAL= include these fields if the information exists, or RECOMMENDED = it is recommended to include these fields but not mandatory.// | ||
+ | |||
+ | | **Attribute** | **Example** | **Description** | | ||
+ | | standard_name (CONDITIONAL) | “sea_water_temperature” | A description of the variable’s content from the CF standard name table. | | ||
+ | | long_name | “Temperature” | A descriptive name that indicates a variable’s content. | | ||
+ | | units | “degree_C” | Use approved CF convention with approved UDUNITS obtained from CF standard name table. | | ||
+ | | scale_factor (CONDITIONAL) | “0.01” | If the data uses a scale_factor other than 1. Should be of the same type as the variable type. | | ||
+ | | add_offset (CONDITIONAL) | “25.0" | ||
+ | | _FillValue (CONDITIONAL) | “-9999” | This value is considered to be a special value that indicates undefined or missing data. Should be of the same type as the variable type. | | ||
+ | | valid_min (RECOMMENDED) | “2.565” | Smallest valid value of a variable. Should be of the same type as the variable type. | | ||
+ | | valid_max (RECOMMENDED) | “23.198” | Largest valid value of a variable. Should be of the same type as the variable type. | | ||
+ | | coordinates (RECOMMENDED) | “T Y X Z” | This attribute contains a space separated list of all the coordinates corresponding to the variable. | | ||
+ | | comment (RECOMMENDED) | “....” | Miscellaneous information about the data, that cannot be described in any of the other available attributes. | | ||
+ | |||
+ | == Quality control flags (CONDITIONAL) == | ||
+ | |||
+ | If applicable to the platform, quality control flags can be self describing variables that show some sort of assessment to identify possible errors in the data. | ||
+ | |||
+ | __Table 6. List of quality control flag variable attributes for SAEON netCDF files__ | ||
+ | |||
+ | //All attributes are MANDATORY to include in your netCDF unless stated: CONDITIONAL= include these fields if the information exists, or RECOMMENDED = it is recommended to include these fields but not mandatory.// | ||
+ | |||
+ | | **Attribute** | **Example** | **Description** | | ||
+ | | standard_name | “....” | A description of the variable’s content from the CF standard name table. | | ||
+ | | long_name | “quality flag for sea_water_temperature” | A descriptive name that indicates a variable’s content. | | ||
+ | | _FillValue (CONDITIONAL) | “-99b” | This value is considered to be a special value that indicates undefined or missing | ||
+ | | flag_values | 0b, 1b, 2b, 3b, 4b, 5b, 6b, 7b | List of flag values used in the data. | | ||
+ | | flag_meanings | " | ||
+ | | comment (RECOMMENDED) | “....” | Miscellaneous information about the data, that cannot be described in any of the other available attributes. | | ||
+ | |||
+ | === NetCDF manipulation tools === | ||
+ | |||
+ | * [[https:// | ||
+ | * [[https:// | ||
+ | * [[http:// | ||