Catalog > ECMWF AIFS ENS forecast > Validation report

ECMWF AIFS ENS forecast validation report

This dataset validation report plots a sample of values from the ECMWF AIFS ENS forecast dataset over time and across space, comparing where possible to a previously validated reference dataset. It also reports the quantity of unavailable values and their associated timestamps. These analyses are one layer of a multi-layered dataset validation process we perform at dynamical.org and also provide users a preview of the dataset contents.

Report generation start time: 2026-05-22T15:13:42 UTC

Summary

This dataset has been validated and is ready for use. We found no data integrity issues — every sampled point and time range is populated, values fall within physically plausible ranges, and spatial fields look correct. One observation about high-latitude temperature_2m is worth flagging when working with the data; it is described in the Review notes below.

What looks good

No missing values at either sampled point across all 17 variables and the full validated time range (2025-07-02 → 2026-05-22).
All spatial maps are oriented correctly, with continents in the expected places and values on the -180° to +180° longitude convention.
For every variable also present in the NOAA GEFS analysis reference, the AIFS value distribution overlaps the reference distribution and falls within physically plausible ranges.
Radiation variables show the expected diurnal cycle in phase with the reference.
Time series at mid-latitude sample points track the reference closely at early lead times and drift gradually thereafter, as expected for a forecast compared against an analysis.
Variables not present in the reference (dew_point_temperature_2m, geopotential_height_850hpa, geopotential_height_925hpa, temperature_850hpa, temperature_925hpa) look smooth and physically reasonable in the AIFS-only plots.

Review notes

The following is a behavioral difference to be aware of when using the dataset, not a data integrity issue.

temperature_2m at high latitudes (|lat| ≥ ~67°) tends to run colder in this AIFS forecast than in the NOAA GEFS analysis, typically by 5–15 °C, with the gap growing as the lead time lengthens. We confirmed the pattern across four additional samples drawn at different ensemble members and initialization times: every Arctic and Antarctic sample point we drew showed AIFS colder than GEFS, including a ~25 °C difference near the North Pole at a 14-day lead. This is the kind of forecast-versus-analysis divergence we'd expect at long lead times in sparsely-observed polar regions and not a defect in the dataset itself.

Datasets

Role	Name	ID	Version	URL
Validation	ECMWF AIFS ENS forecast	`ecmwf-aifs-ens-forecast`	`v0.1.0`	`s3://dynamical-ecmwf-aifs-ens/ecmwf-aifs-ens-forecast/v0.1.0.icechunk`
Reference	NOAA GEFS analysis	`noaa-gefs-analysis`	`0.1.2`	`https://data.dynamical.org/noaa/gefs/analysis/latest.zarr`

Run parameters

Parameter	Value
Validation dataset type	forecast
Validation time range	init_time 2025-07-02T00:00 → 2026-05-22T06:00
Reference time range	time 2000-01-01T00:00 → 2026-05-22T06:00
Time scope	full dataset
Point 1	lat=66.7500, lon=-156.2500
Point 2	lat=-79.7500, lon=104.2500
Ensemble member	7
Spatial comparison time	init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)
Timeseries period	Forecast init_time: 2026-05-01T18:00

Combined plots

Unavailable values: combined_nulls.png
Spatial and distributions: combined_spatial.png
Time series: combined_temporal.png

Unavailable timestamps

None detected at the two sampled points.

Per-variable details

`dew_point_temperature_2m`

Metadata

Field	Value
units	`degree_Celsius`
long_name	2 metre dewpoint temperature
short_name	2d
standard_name	dew_point_temperature
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference not available)

Source	min	mean	max
Validation	-74	1.98	30.12

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	-10	-3.371	1.898
P2 Validation	-69.5	-59.15	-50.25

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$dew_point_temperature_2m — null fraction$

dew_point_temperature_2m — spatial comparison

dew_point_temperature_2m — time series comparison

`downward_long_wave_radiation_flux_surface`

Metadata

Field	Value
units	`W m-2`
long_name	Surface downward long-wave radiation flux
short_name	sdlwrf
standard_name	surface_downwelling_longwave_flux_in_air
step_type	avg

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	61.5	309.6	464
Reference	64	301.4	474

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	203	262.6	316
P1 Reference	200	258.2	324
P2 Validation	62	95.94	140
P2 Reference	67	91.93	142

Nulls — P1: 0/3971880 (none); P2: 0/3971880 (none)

$downward_long_wave_radiation_flux_surface — null fraction$

downward_long_wave_radiation_flux_surface — spatial comparison

downward_long_wave_radiation_flux_surface — time series comparison

`downward_short_wave_radiation_flux_surface`

Metadata

Field	Value
units	`W m-2`
long_name	Surface downward short-wave radiation flux
short_name	sdswrf
standard_name	surface_downwelling_shortwave_flux_in_air
step_type	avg

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	0	164.8	964
Reference	0	179.7	952

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	0.4512	206.5	632
P1 Reference	0	216.4	632
P2 Validation	0	0.4785	5.812
P2 Reference	0	0	0

Nulls — P1: 0/3971880 (none); P2: 0/3971880 (none)

$downward_short_wave_radiation_flux_surface — null fraction$

downward_short_wave_radiation_flux_surface — spatial comparison

downward_short_wave_radiation_flux_surface — time series comparison

`geopotential_height_500hpa`

Metadata

Field	Value
units	`m`
long_name	Geopotential height
short_name	gh
standard_name	geopotential_height
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	4700	5541	5940
Reference	0	5534	5938

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	5242	5360	5450
P1 Reference	5252	5357	5478
P2 Validation	4734	4965	5196
P2 Reference	4908	5012	5086

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$geopotential_height_500hpa — null fraction$

geopotential_height_500hpa — spatial comparison

geopotential_height_500hpa — time series comparison

`geopotential_height_850hpa`

Metadata

Field	Value
units	`m`
long_name	Geopotential height
short_name	gh
standard_name	geopotential_height
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference not available)

Source	min	mean	max
Validation	858.5	1406	1639

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	1224	1387	1508
P2 Validation	1016	1238	1422

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$geopotential_height_850hpa — null fraction$

geopotential_height_850hpa — spatial comparison

geopotential_height_850hpa — time series comparison

`geopotential_height_925hpa`

Metadata

Field	Value
units	`m`
long_name	Geopotential height
short_name	gh
standard_name	geopotential_height
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference not available)

Source	min	mean	max
Validation	198.9	716.1	935

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	550	719.1	846
P2 Validation	380.8	604	786.2

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$geopotential_height_925hpa — null fraction$

geopotential_height_925hpa — spatial comparison

geopotential_height_925hpa — time series comparison

`precipitation_surface`

Metadata

Field	Value
units	`kg m-2 s-1`
long_name	Precipitation rate
short_name	prate
standard_name	precipitation_flux
step_type	avg

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	0	2.851e-05	0.004456
Reference	0	2.732e-05	0.005737

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	mean	max
P1 Validation	1.035e-05	0.0001011
P1 Reference	1.244e-05	0.000145
P2 Validation	7.298e-07	1.395e-05
P2 Reference	7.802e-07	6.467e-06

Nulls — P1: 0/3971880 (none); P2: 0/3971880 (none)

$precipitation_surface — null fraction$

precipitation_surface — spatial comparison

precipitation_surface — time series comparison

`pressure_reduced_to_mean_sea_level`

Metadata

Field	Value
units	`Pa`
long_name	Pressure reduced to MSL
short_name	prmsl
standard_name	air_pressure_at_mean_sea_level
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	9.469e+04	1.009e+05	1.034e+05
Reference	9.504e+04	1.01e+05	1.05e+05

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	9.904e+04	1.012e+05	1.031e+05
P1 Reference	9.958e+04	1.01e+05	1.021e+05
P2 Validation	9.872e+04	1.016e+05	1.043e+05
P2 Reference	1.021e+05	1.036e+05	1.057e+05

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$pressure_reduced_to_mean_sea_level — null fraction$

pressure_reduced_to_mean_sea_level — spatial comparison

pressure_reduced_to_mean_sea_level — time series comparison

`pressure_surface`

Metadata

Field	Value
units	`Pa`
long_name	Surface pressure
short_name	sp
standard_name	surface_air_pressure
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	4.894e+04	9.662e+04	1.044e+05
Reference	5.04e+04	9.66e+04	1.034e+05

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	9.648e+04	9.86e+04	1.004e+05
P1 Reference	9.619e+04	9.753e+04	9.85e+04
P2 Validation	6.019e+04	6.227e+04	6.382e+04
P2 Reference	6.189e+04	6.264e+04	6.323e+04

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$pressure_surface — null fraction$

pressure_surface — time series comparison

`temperature_2m`

Metadata

Field	Value
units	`degree_Celsius`
long_name	2 metre temperature
short_name	2t
standard_name	air_temperature
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	-71	6.407	41
Reference	-66	6.763	38

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	-9.125	1.055	8.875
P1 Reference	-7.906	0.6305	13.19
P2 Validation	-65.5	-55.28	-46.5
P2 Reference	-55	-48.9	-41

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$temperature_2m — null fraction$

`temperature_850hpa`

Metadata

Field	Value
units	`degree_Celsius`
long_name	Temperature
short_name	t
standard_name	air_temperature
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference not available)

Source	min	mean	max
Validation	-44.75	2.459	33.75

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	-9.438	-5.499	-1.992
P2 Validation	-42.25	-35.22	-27.5

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$temperature_850hpa — null fraction$

temperature_850hpa — time series comparison

`temperature_925hpa`

Metadata

Field	Value
units	`degree_Celsius`
long_name	Temperature
short_name	t
standard_name	air_temperature
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference not available)

Source	min	mean	max
Validation	-43	5.197	38.75

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	-9.75	-1.747	3.438
P2 Validation	-38.5	-31.34	-23.62

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$temperature_925hpa — null fraction$

temperature_925hpa — time series comparison

`total_cloud_cover_atmosphere`

Metadata

Field	Value
units	`percent`
long_name	Total cloud cover
short_name	tcc
standard_name	cloud_area_fraction
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	0	70.12	100
Reference	0	60.75	100

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	0.1719	71.99	100
P1 Reference	0	63.78	100
P2 Validation	0	83.27	100
P2 Reference	5	77.36	100

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$total_cloud_cover_atmosphere — null fraction$

total_cloud_cover_atmosphere — spatial comparison

total_cloud_cover_atmosphere — time series comparison

`wind_u_100m`

Metadata

Field	Value
units	`m s-1`
long_name	100 metre U wind component
short_name	100u
standard_name	eastward_wind
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	-31.75	0.1908	32
Reference	-27	0.2757	33.5

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	-9.5	-0.4336	7.125
P1 Reference	-6.562	-1.039	3.312
P2 Validation	-7	3.642	16.5
P2 Reference	-2.25	5.573	12.25

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$wind_u_100m — null fraction$

`wind_u_10m`

Metadata

Field	Value
units	`m s-1`
long_name	10 metre U wind component
short_name	10u
standard_name	eastward_wind
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	-23.25	0.1149	24.75
Reference	-21.75	0.1729	26.5

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	-6.25	-0.1983	4.5
P1 Reference	-6.375	-0.7253	4
P2 Validation	-4.688	3.252	11
P2 Reference	-0.2012	4.363	7.5

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$wind_u_10m — null fraction$

`wind_v_100m`

Metadata

Field	Value
units	`m s-1`
long_name	100 metre V wind component
short_name	100v
standard_name	northward_wind
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	-27.75	0.381	27.75
Reference	-24.25	0.3761	25.75

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	-3.125	0.2967	5.25
P1 Reference	-4.375	-0.6616	4.625
P2 Validation	-6.688	6.769	16.75
P2 Reference	-4	7.805	13.75

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$wind_v_100m — null fraction$

`wind_v_10m`

Metadata

Field	Value
units	`m s-1`
long_name	10 metre V wind component
short_name	10v
standard_name	northward_wind
step_type	instant

Spatial — snapshot at init=2026-05-20T06:00, lead=18h (reference at 2026-05-21T00:00)

Source	min	mean	max
Validation	-19.75	0.3433	21.25
Reference	-19.75	0.2988	21.25

Temporal — period Forecast init_time: 2026-05-01T18:00

Source	min	mean	max
P1 Validation	-1.391	0.2521	3.188
P1 Reference	-2.531	-0.4285	2.344
P2 Validation	-3.312	4.294	11.25
P2 Reference	-2.625	4.099	9.625

Nulls — P1: 0/4038078 (none); P2: 0/4038078 (none)

$wind_v_10m — null fraction$