Removal of Content Advisory - April 2024

Advisory to Gridpoint Statistical Interpolation (GSI) users: As of the beginning of April 2024, all support assets for Gridpoint Statistical Interpolation (GSI) will be removed from the DTC website. Users should download all reference materials of interest prior to April 2024.

Gridpoint Statistical Interpolation (GSI)

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Notice: as of January 2022 DTC has ceased all activities supporting the GSI/EnKF user community. For more details see the full announcement.


Welcome to the users page for the Community Gridpoint Statistical Interpolation (GSI) system. The community GSI system is a variational data assimilation system, designed to be flexible, state-of-art, and run efficiently on various parallel computing platforms. The GSI system is in the public domain and is freely available for community use.

The Developmental Testbed Center (DTC) maintained and supported a community version of the GSI system (last released at version 3.7) through 31 December 2021. The testing and support of this GSI system at the DTC focused on regional numerical weather prediction (NWP) applications coupled with the Weather Research and Forecasting (WRF) Model, but GSI can be applied to the Global Forecast System (GFS) as well as other modeling systems.

GSI is an operational data assimilation system available for community use. Some of these GSI advanced features are:

  • Combined with an ensemble system, GSI can be used as an 3D/4D ensemble-variational hybrid data assimilation system.
  • GSI features capabilities for observation sensitivity calculation. Coupled with its global model, this feature has been used by NASA for its operational data impact study.
  • GSI can be used as an observation operator to provide O-B for the EnKF system or other data analysis systems.

For a complete list of capabilities, please see the GSI User's Guide. We recommend those who use this community service or resources refer to the community GSI in their work and publications: Citation.