Community GSI Users Page

GSI observations

Data format for GSI

The GSI can analyze many types of observational data, including conventional data, satellite radiance obervations, GPS radio occultation observations (bending angle or refractivity), radar data, and others. For use with the GSI, all observations need to in PrepBUFR/BUFR format. A detailed introduction to PrepBUFR/BUFR can be found in the: BUFR Users' Webpage .

Observation data in forms other than PrepBUFR/BUFR must be converted to PrepBUFR/BUFR before they can be used in the GSI. Here is a list of useful websites on this issue:

  • NCEP/NCO website to introduce BUFRLIB and how to decode and encode BUFR files: link
  • BUFR documents in NCAR RDA: link
  • PREPBUFR documents at NCEP: link
  • Observation data processing at NCEP (by Dennis Keyser): link
  • Data Hubs for PrepBUFR/BUFR Data

    The follow is a list of data center that has meteorological histroy data in PREPBUFR format :

    • NCEP NOMADS Site:
    • NCAR CISL Research Data Archive:
      1) Go to
      2) In the "Look For Data" table, click "data format"
      3) Select "WMO BUFR" near the bottom of the list, you will find:
      • 1. Monthly Mean Rawinsondes, from NCEP/NCAR Global Reanalysis, 1948-continuing (ds435.0)
      • 2. NCEP ADP Global Upper Air Observational Weather Data, October 1999 - continuing (ds351.0)
      • 3. VOSCLIM Met Office GTS data (ds540.7)
      • 4. Marine Surface Data from the National Center for Environmental Prediction. (ds540.8)
      • 5. NCEP GDAS Satellite Data 2004-continuing (ds735.0)
      • 6. NCEP ADP Eta (NAM) Subset Surface Observations, October 2000 - October 2010 (ds461.1)
      • 7. NCEP ADP Global Surface Observational Weather Data, October 1999 - continuing (ds461.0)
      • 8. NCEP ADP Global Upper Air and Surface Weather Observations (PREPBUFR format), May 1997 - Continuing (ds337.0)
      • 9. GCIP Canadian Meteorological Centre (CMC) GEM model output, (ds609.3)
      • 10. NCEP Climate Forecast System Initial Conditions, Full Ingest Data (ds099.0)
      • 11. ERA-40 Global Observational Feedback Record Reports (ds117.8)
      • 12. NCEP ADP ETA / NAM Upper Air Observation Subsets, October 2000 - March 2017 (ds351.1)
      • 13. NCEP/NCAR Global Reanalysis Products, 1948-continuing (ds090.0)