The Global Ensemble Forecast System (GEFS) is a weather model created by the National Centers for Environmental Prediction (NCEP) that generates 21 separate forecasts (ensemble members) to address underlying uncertainties in the input data such limited coverage, instruments or observing systems biases, and the limitations of the model itself.
GEFS quantifies these uncertainties by generating multiple forecasts, which in turn produce a range of potential outcomes based on differences or perturbations applied to the data after it has been incorporated into the model. Each forecast compensates for a different set of uncertainties.
GEFS in the NOAA Big Data Program
The NOAA Open Data Dissemination Program provides access to data for multiple resolutions from 1/1/2017–present in the AWS Open Data Registry for GEFS. The NCEI archive of GEFS ends in September 2020 with the resolution change of the product (2.5 to 0.5 degrees and 1.0 to 0.25 degrees). Data on the NODD is not officially archived.
GEFS Analysis
| Model | Grid/Scale | Period of Record | Model Cycle | Output Timestep | Parameter Sets |
|---|---|---|---|---|---|
| GEFS, Control | 1.0, 0.5 and 0.25 degree | 1/1/2017–Present | 4/day: 00, 06, 12, 18UTC | 1/cycle | pgrb2a, pgrb2b |
| GEFS, Perturbed (20 sets) | 1.0, 0.5 and 0.25 degree | 1/1/2017–Present | 4/day: 00, 06, 12, 18UTC | 1/cycle | pgrb2a, pgrb2b |
GEFS Forecasts
| Model | Grid/Scale | Period of Record | Model Cycle | Output Timestep | Parameter Sets |
|---|---|---|---|---|---|
| GEFS, Control | 1.0, 0.5 and 0.25 degree | 1/1/2017–Present | 4/day: 00, 06, 12, 18UTC | 3-hourly, +000 to +384 hours | pgrb2a, pgrb2b |
| GEFS, Perturbed (20 sets) | 1.0, 0.5 and 0.25 degree | 1/1/2017–Present | 4/day: 00, 06, 12, 18UTC | 3-hourly, +000 to +384 | pgrb2a, pgrb2b |
GEFS Data on NCEI Servers
NCEI provides access to gridded GEFS output data on it’s servers. Many other forecast products are available at the NCEP GEFS home page.
Specifications
-
Model: GEFS, 21-Member
| Grid/Scale | Period of Record | Files | Model Cycle | Output Timestep | Data Access Links |
|---|---|---|---|---|
| 003 (1º) *HAS | 01Jan2008–23Sept2020 | 4/day: 00, 06, 12, 18UTC | 6-hourly: Anl, +000 to +384 | NCEI: HAS | |
| 002 (2.5º) *HAS | 01Jan2008–23Sept2020 | 4/day: 00, 06, 12, 18UTC | 6-hourly: Anl, +000 to +384 | NCEI: HAS | |
| 0.5°, 0.25°| NCEP 7–day archive to present | N/A | 4/day: 00, 06, 12, 18UTC | 6-hourly: Anl, +000 to +384 | NCEP: HTTP |
