The National Center for Environmental Prediction (NCEP) uses the Global Data Assimilation System (GDAS) to interpolate data from a variety of observing systems and instruments onto a three-dimensional grid. NCEI provides access to this gridded output data, which is used to initialize the NCEP Global Forecasting System (GFS) model.
Products
| Product | Grid/Scale | Period of Record | Model Cycle | Output Timestep | Data Access Links |
|---|---|---|---|---|---|
| GDAS Snow, Ice, SST, Satellite, Ship, Aircraft (GRIB and BUFR) |
|
01Jan2001–Present (approx. one year to present online) | 4/day: 00, 06, 12, 18UTC | Anl, +00, +03, +06, +09 hours | HTTPS |
| GDAS - Daily Tar Files | 1°x1° | 01Jan2001–21Feb2012 | 4/day: 00, 06, 12, 18UTC | Anl, +00, +03, +06, +09 hours | HAS |
| GDAS - Hourly Tar Files |
|
13Feb2012–Present | 4/day: 00, 06, 12, 18UTC | 4/day: 00, 06, 12, 18UTC | HAS |
| GDAS - Daily BUFR Files |
|
13Feb2012–Present | 4/day: 00, 06, 12, 18UTC | Anl, +00, +03, +06, +09 hours | HAS |
Documentation
- NCEP: GFS/GDAS Changes Since 1991
- NCEP Environmental Modeling Center (EMC) Mesoscale Modeling Branch Publication Listing
- NCEP GDAS Home Page
Specifications
Input Data Formats
Due to the variety of assimilated data types, input data are available in several formats, including:
- Binary Universal Form for the Representation of meteorological data (BUFR)
- Institute of Electrical and Electronics Engineers (IEEE) binary
Output Data Format
World Meteorological Organization (WMO) Gridded Binary (GRIB)
Observation Types
- Surface
- Balloon
- Wind Profiler
- Aircraft Reports
- Buoy
- Radar
- Satellite
