Quoted from: https://www.ncdc.noaa.gov/data-access/model-data/model-datasets/global-forcast-system-gfs
The GFS model is a coupled model, composed of four separate models (an atmosphere model, an ocean model, a land/soil model, and a sea ice model), which work together to provide an accurate picture of weather conditions. Changes are regularly made to the GFS model to improve its performance and forecast accuracy. It is a constantly evolving and improving weather model. Gridded data are available for download through the NOAA National Operational Model Archive and Distribution System (NOMADS). Forecast products and more information on GFS are available at the GFS home page.
Prior to January 2003, the GFS was known as the GFS Aviation (AVN) model and the GFS Medium Range Forecast (MRF) model. GFS-AVN and MRF products are a collection from NCEP's NOAAPort. Grids, domains, run frequencies, and output frequencies have changed over the years.
An animated image of GFS simulated total atmospheric ozone concentration, forecast from 00 UTC on July 12, 2012, to July 16, 2012, at 00 UTC—a four day forecast—in three hourly intervals. The lowest concentrations of ozone on the planet reside over the Antarctic during this period. This image was produced with the Grid Analysis and Display System (GrADS) and ImageMagick.