Product Specific Variables

Provider Defined Variables

All variables defined by the provider have the following attributes. 

type

Definition: data type of variable 

Example: int32, float32, byte

dimension 

Definition: Dimensions of variable. Time is always the first followed by altitude or range when dealing with profiles. Additional dimensions are added at the end.

Example: time

                  time, index

                  time, index_range, index_angle                  

units 

Definition: Units of a variable’s content. 

Example: m s-1 

standard_name 

Definition: A standard name that references a description of a variable’s content in the standard name table. 

Example: air_temperature. If no standard name exists then the attribute is not saved 

long_name 

Definition: Long descriptive name which is often used for labelling plots 

Example: Temperature 

_FillValue 

Definition: This value is considered to be a special value that indicates undefined or missing data, and is returned when reading values that were not written 

Example: -1e+20 

valid_min 

Definition: Smallest valid value of a variable. 

Example: -19 

valid_max 

Definition: Largest valid value of a variable. 

Example: 19 

cell_methods 

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

Example: time: mean 

coordinates 

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

Example: latitude longitude

In some cases additional information is required: for example gas phase chemical species. In these cases two additional variable attributes are used

practical_units

Definition: The common community nomenclature for the canonical unit. 

Example: ppb

chemical_species

Definition: The common community nomenclature for the canonical unit. 

Example: CH4

Example: A profile of wind direction

wind_from_direction

type: float32

dimension: time, index

units: degree

standard_name: wind_from_direction

long_name: Wind Direction

_FillValue: -1.00E+20

valid_min: 88.4

valid_max: 275.6

cell_methods: time: mean

coordinates: latitude longitude

Example: An Ozone Measurement

mole_fraction_of_ozone_in_air

type: float32

dimension: time

units: 1e-9

proctical_units: ppb

standard_name: mole_fraction_of_ozone_in_air

long_name: Mole Fraction of Ozone in air

_FillValue: -1.00E+20

valid_min: 0.6

valid_max: 27

cell_methods: time: mean

coordinates: latitude longitude

chemical_species: O3