Overview Effective 12Z Wednesday, January 14th, 2015, NOAA’s Environmental Modeling Center (EMC) began running an upgraded version of its main computer global forecast model called the Global Forecast System (GFS). The upgraded GFS model has greater horizontal resolution compared to its predecessor version and the higher resolution runs now extend farther out in time. In preparation for the upgraded computer forecast model, NOAA has recently upgraded its computing capability with each of its two supercomputers by more than tripling their capacity. Much of this effort of upgrading the computer forecast model and computing capability was accelerated after Hurricane Sandy struck the Northeast US in 2012 as the main NOAA forecast model produced some inferior results in its prediction of the storm track when compared to its equivalent European counterpart.
Global Forecast System (GFS) The upgraded GFS model now has increased horizontal resolution in the first segment of its forecast package from 27 to 13 km and this higher resolution now extends out to 10 days whereas previously the higher resolution only went out to 7.5 days. The second segment of the GFS forecast package has seen an increase in horizontal resolution from 55 to 35 km which extends out from 10 days to 16 days. Furthermore, the upgraded model has enhanced physics and a better handling of important parameters such as sea surface temperatures, sea ice concentration, and snow depth which are all utilized by the model.
Computing power Modern numerical weather prediction uses the world’s most powerful computers and the associated software includes millions of lines of code. Some of the biggest computers in the world are used for weather and climate simulations. NOAA has upgraded its computing capability with each of its two supercomputers by more than tripling their capacity to at least 0.776 petaflops for a total capacity of 1.552 petaflops (a petaflop is a thousand trillion operations per second). The amount of data collected for operational numerical weather prediction is mind boggling. Petabytes of weather data are streaming to earth from dozens of weather satellites each day. In addition, hundreds of thousands of surface stations, roughly a thousand radiosondes, thousands of ships and buoys, thousands of aircraft, lightning detection networks, and other sensors are reporting each day adding up to hundreds of terabytes of information. All of this data is distributed around the world, quality controlled, and used to provide a physically consistent description of the three-dimensional atmosphere (info here provided courtesy Cliff Mass, University of Washington). Additional computing capacity and forecast model upgrades are scheduled by NOAA during the next few years.