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Global Data Assimilation System

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

ProductGrid/ScalePeriod of RecordModel CycleOutput TimestepData Access Links
GDAS Snow, Ice, SST, Satellite, Ship, Aircraft (GRIB and BUFR)
  • 1°x1°
  •  0.5°x0.5° 
  • 0.25°x0.25°
01Jan2001–Present (approx. one year to present online)

4/day: 00, 06, 12, 18UTC

Anl, +00, +03, +06, +09 hoursHTTPS
GDAS - Daily Tar Files1°x1°01Jan2001–21Feb2012

4/day: 00, 06, 12, 18UTC

Anl, +00, +03, +06, +09 hoursHAS
GDAS - Hourly Tar Files
  • 1°x1°
  • 0.5°x0.5°
  • 0.25°x0.25°
13Feb2012–Present

4/day: 00, 06, 12, 18UTC

4/day: 00, 06, 12, 18UTCHAS
GDAS - Daily BUFR Files
  • 1°x1°
  • 0.5°x0.5°
  • 0.25°x0.25°
13Feb2012–Present

4/day: 00, 06, 12, 18UTC

Anl, +00, +03, +06, +09 hoursHAS

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 Formats
  • World Meteorological Organization (WMO) Gridded Binary (GRIB)
Observation Types
  • Surface
  • Balloon
  • Wind Profiler
  • Aircraft Reports
  • Buoy
  • Radar
  • Satellite

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