Feature Representation

In addition to the generic FME feature attributes that FME Workbench adds to all features (see About Feature Attributes), this format adds the format-specific attributes described in this section.

The following FME attributes describe properties of the netCDF dataset.

Attribute Name Contents

netcdf_type

This will always be netcdf_raster.

netcdf_format

Format of the netCDF dataset.

Valid values are CLASSIC and 64_BIT_OFFSET.

This is a reader attribute.

netcdf_subdataset_name

When this is present on a feature, the feature is a subdataset. This attribute shows the name of the subdataset.

This is a reader attribute.

netcdf_subdataset_description

When this is present on a feature, the feature is a subdataset. This attribute gives a description of the subdataset.

This is a reader attribute.

The following FME attributes are stored as global attributes in the netCDF dataset.

Attribute Name Contents
netcdf_comment Miscellaneous information about the data or methods used to produce it.
netcdf_conventions Name of the conventions followed by the dataset. By default, the writer will write CF-1.5 conventions. Note that specifying a different value will not necessarily make the data conform to those conventions.
netcdf_history List of the applications that have modified the original data.
netcdf_institution Where the original data was produced.
netcdf_references References that describe the data or methods used to produce it.
netcdf_source Method of production of the original data.
netcdf_title Short description of the file contents.

The following FME attributes are used to describe/define dimensions and coordinate variables in the netCDF dataset.

Attribute Name Contents
netcdf_coordinate_variable{}.name Name of the dimension / coordinate variable.
netcdf_coordinate_variable{}.type Type of the coordinate variable. Valid values are byte, short, int, float, double.
netcdf_coordinate_variable{}.axis Identifies latitude, longitude, vertical, or time axes.
netcdf_coordinate_variable{}.bounds

Identifies a boundary variable.

This is a reader attribute.

netcdf_coordinate_variable{}.calendar Calendar used for encoding time axes.
netcdf_coordinate_variable{}.compress

Records dimensions which have been compressed by gathering.

This is a reader attribute.

netcdf_coordinate_variable{}.climatology

Identifies a climatology variable.

This is a reader attribute.

netcdf_coordinate_variable{}.formula_terms

Identifies variables that correspond to the terms in a formula.

This is a reader attribute.

netcdf_coordinate_variable{}.leap_month Specifies which month is lengthened by a day in leap years for a user defined calendar.
netcdf_coordinate_variable{}.leap_year Provides an example of a leap year for a user defined calendar. It is assumed that all years that differ from this year by a multiple of four are also leap years.
netcdf_coordinate_variable{}.long_name A descriptive name that indicates a variable's content. This name is not standardized.
netcdf_coordinate_variable{}.month_lengths{} Specifies the length of each month in a non-leap year for a user defined calendar.
netcdf_coordinate_variable{}.positive Direction of increasing vertical coordinate value.
netcdf_coordinate_variable{}.standard_name A standard name that references a description of a variable's content in the standard name table.
netcdf_coordinate_variable{}.units Units of a variable's content.
netcdf_coordinate_variable{}.valid_max Largest valid value of a variable.
netcdf_coordinate_variable{}.valid_min Smallest valid value of a variable.
netcdf_coordinate_variable{}.valid_range{} Smallest and largest valid values of a variable.

netcdf_coordinate_variable{}.user_attrs{}.name

netcdf_coordinate_variable{}.user_attrs{}.type

netcdf_coordinate_variable{}.user_attrs{}.value

Together these three values specify an attribute that will be connected to a coordinate variable. Name specifies the name of the attribute. Type specifies the type of the attribute. Valid values are char, byte, short, int, float, double. Value specifies the value of the attribute.
netcdf_band{}.coordinate_variable{}

Specifies the value for each "extra" (i.e. non-x/y) coordinate variable corresponding to each band. For example, suppose a data variable depends on two extra dimensions: {year, month }, where year has values {2000, 2001} and month has values {1, 2, ..., 12}. Then the raster will have 24 bands, and the values for this attribute will be as follows: netcdf_band{0}.coordinate_variable{0} = 2000 netcdf_band{0}.coordinate_variable{1} = 1 netcdf_band{1}.coordinate_variable{0} = 2000 netcdf_band{1}.coordinate_variable{1} = 2

...

netcdf_band{11}.coordinate_variable{0} = 2000 netcdf_band{11}.coordinate_variable{1} = 12 netcdf_band{12}.coordinate_variable{0} = 2001 netcdf_band{12}.coordinate_variable{1} = 1

...

netcdf_band{23}.coordinate_variable{0} = 2001 netcdf_band{23}.coordinate_variable{1} = 12

The following FME attributes are used to describe/define the data variable in the netCDF dataset.

Attribute Name Contents
netcdf_data_variable.name Name of the data variable.
   
netcdf_data_variable.add_offset Specifies an offset to be added to each value for a variable.
   
netcdf_data_variable.ancillary_variables

Identifies a variable that contains closely associated data, e.g., the measurement uncertainties of instrument data.

This is a reader attribute.

netcdf_data_variable.cell_measures

Identifies variables that contain cell areas or volumes.

This is a reader attribute.

netcdf_data_variable.cell_methods

Records the method used to derive data that represents cell values.

This is a reader attribute.

netcdf_data_variable.comment Miscellaneous information about the data or methods used to produce it.
netcdf_data_variable.coordinates

Identifies auxiliary coordinate variables, label variables, and alternate coordinate variables.

This is a reader attribute.

netcdf_data_variable.flag_masks{} Provides a list of bit fields expressing Boolean or enumerated flags.
netcdf_data_variable.flag_meanings Use in conjunction with flag_values to provide descriptive words or phrases for each flag value. If multi-word phrases are used to describe the flag values, then the words within a phrase should be connected with underscores.
netcdf_data_variable.flag_values{} Provides a list of the flag values. Use in conjunction with flag_meanings.
netcdf_data_variable.grid_mapping Identifies the name of a variable that defines a grid mapping.
netcdf_data_variable.institution Where the original data was produced.
netcdf_data_variable.long_name A descriptive name that indicates a variable's content. This name is not standardized.
netcdf_data_variable.references References that describe the data or methods used to produce it.
netcdf_data_variable.scale_factor Specifies an offset to be multiplied with each value for a variable.
netcdf_data_variable.source Method of production of the original data.
netcdf_data_variable.standard_error_multiplier If a data variable with a standard_name modifier of standard_error has this attribute, it indicates that the values are the stated multiple of one standard error.
netcdf_data_variable.standard_name A standard name that references a description of a variable's content in the standard name table.
netcdf_data_variable.units Units of a variable's content.
netcdf_data_variable.valid_max Largest valid value of a variable.
netcdf_data_variable.valid_min Smallest valid value of a variable.
netcdf_data_variable.valid_range{} Smallest and largest valid values of a variable.

netcdf_data_variable.user_attrs{}.name

netcdf_data_variable.user_attrs{}.type

netcdf_data_variable.user_attrs{}.value

Together these three values specify an attribute that will be connected to the data variable.

Name specifies the name of the attribute.

Type specifies the type of the attribute. Valid values are char, byte, short, int, float, double.

Value specifies the value of the attribute.