HRRR Composite Reflectivity image

Assimilation Development Branch

Making Forecasts Better

GSD's Earth Modeling develops storm-scale-to-global scale weather, air quality, coupled, and seasonal data assimilation and prediction models to be used in forecast operations. These modeling systems deliver forecasts and predictions of weather, including severe weather events, within the next few minutes to weeks away. As part of that work, the Assimilation Development Branch develops advanced observational data assimilation techniques, including for radar and satellite data but also for all observational data. These assimilation techniques are applied in particular for regional models but with some applications starting for global model data assimilation.

Earth Modeling as a whole, works to:

  • Develop research modeling and assimilation suitable for operations
  • Transfer research to operations primarily within NOAA
  • Collaborate and innovate within community modeling and assimilation efforts including NCEP, NCAR, other ESRL divisions and OAR laboratories, universities, international communities
  • Address both global and regional modeling efforts with the same scientific expertise/techniques/code where possible
  • Work with other ESRL divisions and GSD branches to broaden atmospheric modeling into Earth system including chemistry, ocean, and biosphere




Forecast Models



    FIM Image - Precipitable Water

    GSD's FIM (Flow-Following Finite-Volume Icosahedral Model) uses a unique hexagonal mesh grid to improve modeling of weather systems at all latitudes from very short-range to week 3-4. GSD also has experience on development of non-hydrostatic global models and is involved in initial planning and development toward NOAA's Next-Generation Global Prediction System (NGGPS).


  • HRRR (3km)

    HRRR Composite Reflectivity

    The High-Resolution Rapid Refresh (HRRR) is the only hourly updating model that can predict individual thunderstorms on a 3km grid over the U.S.

  • RAP (13km)

    RAP Surface Temperature image

    The Rapid Refresh (RAP) is NOAA’s North American hourly-updating model system that ingests data from a network of ground and satellite-based sensors, radar, and aircraft.


  • WRF-Chem

    WRF-Chem Image

    GSD leads the development of WRF-Chem (Weather Research and Forecasting - Chemistry), a next-generation coupled weather and air quality prediction system based on the existing Weather Research and Forecast Model.

  • Nowcasting

    LAPS All-sky Image

    EMB scientists are focused on the application of Gridpoint Statistical Interpolation (GSI) to nowcasting applications including RTMA (Real-Time Mesoscale Analysis) and its 3-d counterpart, the Rapidly Updated Analysis (RUA).