Naming (All Existing Models)

This document describes the standardized variable naming conventions used across all current Jua models, including EPT-2 and newer models.

Variable Naming Structure

Variables follow these patterns:

Basic Pattern

{parameter_name}_at_{location_type}_{value}{unit}

Where:

• {parameter_name}: Physical quantity based on CF standard name (e.g., air_temperature)

• _at_: Standard connecting phrase

• {location_type}: Reference surface type (e.g., pressure_level, height_level, surface)

• {value}: Numerical value of the level (e.g., 2, 100000)

• {unit}: Unit of the level measurement (e.g., m for meters, Pa for Pascals)

Special Cases

Some variables don't require reference surface specification in the name. These include:

• Variables containing "atmosphere_mass_content"

• Variables containing "surface" or "toa"

• Specific variables like "freezing_level_altitude", "precipitation_amount", etc.

• Variables with reference surfaces like "mean_sea_level", cloud layers, etc.

Time Periods and Accumulations

For variables involving time aggregation, additional suffixes are added:

Mean Values

{base_variable_name}_mean_{aggregation_time}

Sum Values

{base_variable_name}_sum_{aggregation_time}

Where {aggregation_time} indicates the time period of the aggregation.

Common Weather Variables

Examples of common variables following this convention:

Variable Name	Unit
air_temperature_at_height_level_2m	K
dew_point_temperature_at_height_level_2m	K
relative_humidity_at_height_level_2m	range between [0,1]
air_pressure_at_mean_sea_level	Pa
wind_speed_at_height_level_10m	m s⁻¹
wind_direction_at_height_level_10m	Degrees true
wind_speed_at_height_level_100m	m s⁻¹
wind_direction_at_height_level_100m	Degrees true
geopotential_at_pressure_level_50000Pa	m² s⁻²
surface_direct_downwelling_shortwave_flux_sum_1h	J m⁻²
surface_downwelling_shortwave_flux_sum_1h	J m⁻²
surface_downwelling_longwave_flux_sum_1h	J m⁻²
precipitation_amount_sum_1h	mm m⁻²
cloud_area_fraction_at_entire_atmosphere_high_type	range between [0,1]
cloud_area_fraction_at_entire_atmosphere_medium_type	range between [0,1]
cloud_area_fraction_at_entire_atmosphere_low_type	range between [0,1]
cloud_area_fraction_at_entire_atmosphere	range between [0,1]

Key Differences from Legacy Naming

The current naming convention differs from EPT-1.5 (legacy) naming in several key ways:

1. Descriptive vs. Code-based: New names are fully descriptive (e.g., air_temperature_at_height_level_2m) rather than using short codes (e.g., 2t).

2. Standardized Structure: New names follow a consistent {parameter}_at_{location_type}_{value}{unit} pattern, making the naming system more predictable.

3. Explicit Units: Current naming explicitly includes measurement units in the variable name (e.g., 50000Pa, 2m).

4. Reference Surface: Current naming explicitly states the reference surface (e.g., at_pressure_level, at_height_level).

5. Time Aggregation: New naming includes standardized suffixes for time aggregation (_mean_, _sum_).

6. Consistent Across Interfaces: Unlike in EPT-1.5 where hindcast and API names differed, this naming convention is valid for any interface at Jua.

See the Legacy Naming (EPT-1.5) document for details on the previous naming system.