AIFS Hindcasts

Important Parameter Naming Disclaimer:

• Parameter names have changed from ECMWF shortnames to human-readable longnames based on customer requests (e.g., "2t" is now "air_temperature_at_height_level_2m")

• All AIFS products use the new human-readable parameter names

Technical specifications are available in a technical specifications document here.

Hindcasts Details

• Hindcasts are global with a grid of 721×1440

• Hindcasts are from 2023-01-02 to 2024-12-27

• Hindcasts are run 4 times a day at 00, 06, 12, 18 UTC

• Hindcasts are chunked as (time: 1, prediction_timedelta: 81, lat: 120, lon: 240)

• Forecasts are 6 hourly from days 0 to 20

• Access URL: https://data.jua.ai/hindcasts/aifs/v1/global/2023-01-02-to-2024-12-27.zarr

Coordinates

Name	Description	Units
time	Initialization time of forecast at UTC	Absolute time (UTC)
prediction_timedelta	Lead time relative to initialization time	Timedelta
latitude	Latitudinal coordinate	Degrees true, range [90, -90]
longitude	Longitudinal coordinate	Degrees true, range [-180, 180)

Exposed Variables

Name	EMCWF Code	Description	Units
air_temperature_at_height_level_2m	2t	Air temperature at 2m	K
wind_speed_at_height_level_10m	10si	Horizontal wind speed at 10m	m s⁻¹
wind_direction_at_height_level_10m	10wdir	Horizontal wind direction at 10m	Degrees true
wind_speed_at_height_level_100m	100si	Horizontal wind speed at 100m	m s⁻¹
wind_direction_at_height_level_100m	100wdir	Horizontal wind direction at 100m	Degrees true
air_pressure_at_mean_sea_level	msl	Mean Sea-level Pressure	Pa
geopotential_at_pressure_level_50000Pa	z_500	Geopotential	m² s⁻²
surface_downwelling_shortwave_flux_sum_6h	ssrd	Surface solar downward irradiance	J m⁻²
surface_downwelling_longwave_flux_sum_1h	strd	Surface thermal downward irradiance	J m⁻²
high_type_cloud_area_fraction	hcc	Cloud fraction in high levels of troposphere	range between [0,1]
medium_type_cloud_area_fraction	mcc	Cloud fraction in medium levels of troposphere	range between [0,1]
low_type_cloud_area_fraction	lcc	Cloud fraction in low levels of troposphere	range between [0,1]
cloud_area_fraction_at_entire_atmosphere	tcc	Cloud fraction	range between [0,1]

Additional Variables on Request

Name	EMCWF Code	Description	Units
atmosphere_mass_content_of_water_vapor	tcwv	Total column vertically-integrated water vapour	kg m⁻²
dew_point_temperature_at_height_level_2m	2d	2 metre dewpoint temperature	K
air_temperature_at_pressure_level (at 13 levels)	t	Temperature at a specified pressure level	K
eastward_wind_at_pressure_level (at 13 levels)	u	U component of wind	m s⁻¹
northward_wind_at_pressure_level (at 13 levels)	v	V component of wind	m s⁻¹
specific_humidity_at_pressure_level (at 13 levels)	q	The mass of water vapour per kilogram of moist air at a specified pressure level	kg kg⁻¹
geopotential_at_pressure_level (at 13 levels)	z	The gravitational potential energy of a unit mass	m² s⁻²

Pressure levels: 5000, 10000, 15000, 20000, 25000, 30000, 40000, 50000, 60000, 70000, 85000, 92500, 100000 Pa