Common variables
These 18 variables are saved by every 0.25° model — GraphCast, Aurora 1.5, AIFS-single v2, AIFS-ENS v2, FGN, and Aurora 1.5 ENS — with the same units and temporal aggregation. The model sections below list only the variables each model adds on top of this set. NeuralGCM runs on a different grid with its own variable naming and is listed in full in its own section.
| Variable | Units | Temporal aggregation |
|---|---|---|
2 m temperature (2t) | K | 6-hourly instantaneous |
Mean sea level pressure (mslp) | Pa | 6-hourly instantaneous |
Specific humidity at 1000 hPa (q_1000) | kg kg⁻¹ | 6-hourly instantaneous |
Specific humidity at 925 hPa (q_925) | kg kg⁻¹ | 6-hourly instantaneous |
Specific humidity at 850 hPa (q_850) | kg kg⁻¹ | 6-hourly instantaneous |
Temperature at 1000 hPa (t_1000) | K | 6-hourly instantaneous |
Temperature at 925 hPa (t_925) | K | 6-hourly instantaneous |
Temperature at 850 hPa (t_850) | K | 6-hourly instantaneous |
Total precipitation (tp) | m | Daily accumulation (UTC day) |
U wind component at 50 hPa (u_50) | m s⁻¹ | Daily mean (UTC day) |
U wind component at 200 hPa (u_200) | m s⁻¹ | Daily mean (UTC day) |
U wind component at 850 hPa (u_850) | m s⁻¹ | Daily mean (UTC day) |
V wind component at 50 hPa (v_50) | m s⁻¹ | Daily mean (UTC day) |
V wind component at 200 hPa (v_200) | m s⁻¹ | Daily mean (UTC day) |
V wind component at 850 hPa (v_850) | m s⁻¹ | Daily mean (UTC day) |
Geopotential at 200 hPa (z_200) | m² s⁻² | Daily mean (UTC day) |
Geopotential at 500 hPa (z_500) | m² s⁻² | Daily mean (UTC day) |
Geopotential at 850 hPa (z_850) | m² s⁻² | Daily mean (UTC day) |
Mean sea level pressure is named msl in
AIFS-ENS v2 and mslp in the other models.
GraphCast
Class: deterministic Grid: 721 × 1440 (0.25°) Forecast length: 50 days
GraphCast saves the common variables only.
Aurora 1.5
Class: deterministic Grid: 720 × 1440 (0.25°) Forecast length: 50 days
| Variable | Units | Temporal aggregation |
|---|---|---|
2 m dewpoint temperature (2d) | K | 6-hourly instantaneous |
Surface pressure (sp) | Pa | 6-hourly instantaneous |
Soil temperature level 1 (stl1) | K | 6-hourly instantaneous |
Volumetric soil water layer 1 (swvl1) | m³ m⁻³ | 6-hourly instantaneous |
Daily maximum 2 m temperature (2t_max) | K | Daily maximum (UTC day) |
Daily minimum 2 m temperature (2t_min) | K | Daily minimum (UTC day) |
AIFS-single v2
Class: deterministic Grid: 721 × 1440 (0.25°) Forecast length: 50 days
| Variable | Units | Temporal aggregation |
|---|---|---|
2 m dewpoint temperature (2d) | K | 6-hourly instantaneous |
Surface pressure (sp) | Pa | 6-hourly instantaneous |
Soil temperature level 1 (stl1) | K | 6-hourly instantaneous |
Soil temperature level 2 (stl2) | K | 6-hourly instantaneous |
Volumetric soil water layer 1 (swvl1) | m³ m⁻³ | 6-hourly instantaneous |
Volumetric soil water layer 2 (swvl2) | m³ m⁻³ | 6-hourly instantaneous |
Total column water (tcw) | kg m⁻² | Daily mean (UTC day) |
AIFS-ENS v2
Class: ensemble Grid: 721 × 1440 (0.25°) Ensemble members: 51 Forecast length: 50 days
| Variable | Units | Temporal aggregation |
|---|---|---|
2 m dewpoint temperature (2d) | K | 6-hourly instantaneous |
Surface pressure (sp) | Pa | 6-hourly instantaneous |
Soil temperature level 1 (stl1) | K | 6-hourly instantaneous |
Soil temperature level 2 (stl2) | K | 6-hourly instantaneous |
Volumetric soil water layer 1 (swvl1) | m³ m⁻³ | 6-hourly instantaneous |
Volumetric soil water layer 2 (swvl2) | m³ m⁻³ | 6-hourly instantaneous |
Total column water (tcw) | kg m⁻² | Daily mean (UTC day) |
FGN
Class: ensemble Grid: 721 × 1440 (0.25°) Ensemble members: 51 Forecast length: 50 days
| Variable | Units | Temporal aggregation |
|---|---|---|
Sea surface temperature (sst) | K | 6-hourly instantaneous |
Aurora 1.5 ENS
Class: ensemble Grid: 720 × 1440 (0.25°) Ensemble members: 51 Forecast length: 50 days
| Variable | Units | Temporal aggregation |
|---|---|---|
2 m dewpoint temperature (2d) | K | 6-hourly instantaneous |
Surface pressure (sp) | Pa | 6-hourly instantaneous |
Soil temperature level 1 (stl1) | K | 6-hourly instantaneous |
Volumetric soil water layer 1 (swvl1) | m³ m⁻³ | 6-hourly instantaneous |
Daily maximum 2 m temperature (2t_max) | K | Daily maximum (UTC day) |
Daily minimum 2 m temperature (2t_min) | K | Daily minimum (UTC day) |
NeuralGCM
Class: ensemble Grid: 64 × 128 (≈2.8°) Ensemble members: 51 Forecast length: 50 days
| Variable | Units | Temporal aggregation |
|---|---|---|
Temperature at 1000 hPa (temperature_1000) | K | 6-hourly instantaneous |
Temperature at 925 hPa (temperature_925) | K | 6-hourly instantaneous |
Specific humidity at 1000 hPa (specific_humidity_1000) | kg kg⁻¹ | 6-hourly instantaneous |
Geopotential at 200 hPa (geopotential_200_avg) | m² s⁻² | Daily mean (UTC day) |
Geopotential at 500 hPa (geopotential_500_avg) | m² s⁻² | Daily mean (UTC day) |
Geopotential at 850 hPa (geopotential_850_avg) | m² s⁻² | Daily mean (UTC day) |
Specific humidity at 925 hPa (specific_humidity_925_avg) | kg kg⁻¹ | Daily mean (UTC day) |
Specific humidity at 850 hPa (specific_humidity_850_avg) | kg kg⁻¹ | Daily mean (UTC day) |
Temperature at 200 hPa (temperature_200_avg) | K | Daily mean (UTC day) |
Temperature at 500 hPa (temperature_500_avg) | K | Daily mean (UTC day) |
Temperature at 850 hPa (temperature_850_avg) | K | Daily mean (UTC day) |
U wind component at 50 hPa (u_component_of_wind_50_avg) | m s⁻¹ | Daily mean (UTC day) |
U wind component at 200 hPa (u_component_of_wind_200_avg) | m s⁻¹ | Daily mean (UTC day) |
U wind component at 500 hPa (u_component_of_wind_500_avg) | m s⁻¹ | Daily mean (UTC day) |
U wind component at 850 hPa (u_component_of_wind_850_avg) | m s⁻¹ | Daily mean (UTC day) |
V wind component at 50 hPa (v_component_of_wind_50_avg) | m s⁻¹ | Daily mean (UTC day) |
V wind component at 200 hPa (v_component_of_wind_200_avg) | m s⁻¹ | Daily mean (UTC day) |
V wind component at 500 hPa (v_component_of_wind_500_avg) | m s⁻¹ | Daily mean (UTC day) |
V wind component at 850 hPa (v_component_of_wind_850_avg) | m s⁻¹ | Daily mean (UTC day) |
Total precipitation, 24 h accumulation (total_precipitation_24hr) | m | 24 h accumulation (UTC day) |
Variable selection
Variables were selected for
their utility in human-centered benchmarking of high-impact phenomena
(heat waves, cold air outbreaks, heavy precipitation), for general
geoscience research use, and for driver analysis of the large-scale
atmospheric patterns that condition those phenomena — blocking and Rossby
wave activity (z_500, z_200), jet position and
storm tracks (u_200, v_200, u_850,
v_850), stratospheric variability and its surface coupling
(u_50, v_50), and lower-tropospheric moisture and
thermal structure (q_1000–q_850,
t_1000–t_850).
Temporal aggregation follows the same logic: fields used for extremes and threshold exceedance are kept 6-hourly, while circulation diagnostics are stored as daily means.
Archive structure & format
Forecasts are stored as one zarr store per model per initialization:
forecasts_<model>/init_YYYYMMDDT00.zarr. Dimensions are
(time, [number,] prediction_timedelta, lat, lon) for 6-hourly
fields and prediction_timedelta_daily for daily aggregates;
number is the ensemble-member dimension. All data are
float32.
Daily aggregates are given by: means of the four 6-hourly values in the UTC calendar day; precipitation is the daily accumulation; 2 m temperature max/min are daily extremes.