Global Forecast System

Global Forecast System
NWS, which is a branch of NOAA, a US government agency · Public domain · source
Name	Global Forecast System
Type	Global forecast model
Developer	National Centers for Environmental Prediction
Operator	National Weather Service
Launched	1970s (as Spectral Statistical Interpolation)
Status	Operational
Website	[https://www.emc.ncep.noaa.gov/emc/pages/numerical_forecast_systems/gfs.php NCEP GFS Page]

Global Forecast System. It is a global numerical weather prediction system operated by the National Centers for Environmental Prediction as part of the National Weather Service within the National Oceanic and Atmospheric Administration. The system generates essential forecasts for atmospheric conditions, providing critical guidance for meteorologists worldwide and supporting a vast array of weather-sensitive activities from aviation to agriculture.

Overview

The primary function is to produce detailed forecasts of atmospheric variables such as temperature, wind, and precipitation across the entire globe. These forecasts are generated by solving complex mathematical equations that govern atmospheric physics on a supercomputer located at the National Centers for Environmental Prediction. Output from the model is used extensively by the National Hurricane Center for tracking tropical cyclones and by global entities like the European Centre for Medium-Range Weather Forecasts for comparative analysis. Its data forms the backbone for many downstream applications, including specialized models for regions like the North Atlantic Ocean and public forecasts issued by local Weather Forecast Office stations.

History and development

Its origins trace back to the first operational numerical weather prediction efforts in the 1950s, with significant evolution through projects like the Global Weather Experiment. The modern system was formally implemented in the late 1970s, initially known as the Spectral Statistical Interpolation analysis scheme. Major upgrades have been driven by advancements in supercomputing, such as those at the Oak Ridge National Laboratory, and collaborations with research institutions like the Geophysical Fluid Dynamics Laboratory. A landmark revision occurred with the implementation of the Finite-Volume Cubed-Sphere dynamical core, significantly improving resolution and accuracy. Continuous development is managed through partnerships with agencies including the National Aeronautics and Space Administration and the United States Navy.

Model components and structure

The system integrates several sophisticated components, starting with a data assimilation system that ingests millions of observations from sources like Geostationary Operational Environmental Satellite, Advanced Microwave Sounding Unit, and global radiosonde networks. Its dynamical core uses a finite difference method on a latitude-longitude grid to solve the primitive equations of fluid motion. Physical parameterization schemes model critical processes such as cloud microphysics, radiative transfer influenced by gases like ozone, and land-surface interactions using datasets from the United States Geological Survey. The coupled model also includes components for ocean waves and sea ice, utilizing data from the National Ice Center.

Operational implementation

Operational runs are executed four times daily on supercomputers at the National Centers for Environmental Prediction, with computational support from facilities like the Weather and Climate Operational Supercomputing System. The main forecast cycle produces output out to 16 days, with ensemble prediction systems like the Global Ensemble Forecast System providing probabilistic guidance. Real-time products are disseminated globally via the World Meteorological Organization's Global Telecommunication System. High-priority users, such as the Federal Aviation Administration and the United States Department of Agriculture, receive tailored products for aviation safety and agricultural planning.

Performance and accuracy

Its skill is routinely evaluated against other global models, notably the European Centre for Medium-Range Weather Forecasts' Integrated Forecasting System, and through verification programs like the World Meteorological Organization's World Weather Research Programme. Performance can vary by region and season, with particular scrutiny on high-impact events like Hurricane Katrina or Superstorm Sandy. The introduction of higher resolution and improved physics, such as better representation of the Madden–Julian oscillation, has steadily increased forecast skill. Comparative studies are often published in journals like the Monthly Weather Review.

Applications and impact

Output is fundamental to weather forecasting and warning operations at the Storm Prediction Center and the National Tsunami Warning Center. It drives specialized models for air quality prediction by the Environmental Protection Agency and for wave forecasting by the Ocean Prediction Center. The system's data supports economic sectors worldwide, informing commodity trading on the Chicago Mercantile Exchange and logistics for companies like FedEx. Its open-data policy has also fostered innovation in private-sector weather companies and academic research at universities like the Massachusetts Institute of Technology.

Category:Numerical climate and weather models Category:National Weather Service Category:Atmospheric dynamics