Global Forecast System

Global Forecast System
NWS, which is a branch of NOAA, a US government agency · Public domain · source
Name	Global Forecast System
Developer	National Centers for Environmental Prediction

Global Forecast System. The Global Forecast System (GFS) is a numerical weather prediction model developed by the National Centers for Environmental Prediction (NCEP), which is part of the National Weather Service (NWS) under the National Oceanic and Atmospheric Administration (NOAA). The GFS model is used to forecast the weather and climate of the Earth by solving the Navier-Stokes equations and other related equations. The GFS model is run on a supercomputer at the National Weather Service's National Centers for Environmental Prediction and provides forecasts for the United States and other countries around the world, including Canada, Mexico, and Europe, in collaboration with the European Centre for Medium-Range Weather Forecasts (ECMWF) and the Japan Meteorological Agency (JMA).

Introduction

The Global Forecast System is a complex model that uses a variety of atmospheric and oceanic data, including satellite imagery from NASA's Geostationary Operational Environmental Satellite (GOES) and European Space Agency's (ESA) Meteosat, to forecast the weather and climate. The model is based on the finite volume method and uses a grid with a resolution of approximately 13 kilometers to solve the Navier-Stokes equations. The GFS model is also coupled with other models, such as the Wave Watch III model, which is used to forecast ocean waves, and the Hydrologic Research Center's (HRC) Snow Model, which is used to forecast snow and ice. The GFS model provides forecasts for a wide range of weather phenomena, including tornadoes, hurricanes, and blizzards, and is used by meteorologists at the National Weather Service's Storm Prediction Center (SPC) and the National Hurricane Center (NHC).

History and Development

The Global Forecast System was first developed in the 1980s by the National Meteorological Center (NMC), which is now part of the National Centers for Environmental Prediction. The first version of the GFS model was released in 1985 and was based on the spectral method. Over the years, the GFS model has undergone significant improvements, including the addition of new physics packages, such as the Ferrier-Aligo microphysics scheme, and the use of more advanced numerical methods, such as the semi-Lagrangian method. The GFS model has also been coupled with other models, such as the Climate Forecast System (CFS) model, which is used to forecast climate variability, and the North American Mesoscale Forecast System (NAM) model, which is used to forecast mesoscale weather phenomena. The GFS model has been used to forecast weather phenomena, such as the 1993 Storm of the Century and Hurricane Katrina, in collaboration with the Federal Emergency Management Agency (FEMA) and the National Guard.

Model Components

The Global Forecast System model consists of several components, including the atmospheric model, the ocean model, and the land surface model. The atmospheric model is based on the hydrostatic equation and uses a sigma-coordinate system to solve the Navier-Stokes equations. The ocean model is based on the primitive equations and uses a z-coordinate system to solve the ocean circulation equations. The land surface model is based on the energy balance equation and uses a tile approach to solve the land surface energy balance equations. The GFS model also includes a variety of physics packages, such as the radiation scheme and the turbulence scheme, which are used to simulate the atmospheric and oceanic processes. The GFS model is also coupled with other models, such as the Chemical Transport Model (CTM), which is used to forecast air quality, and the Hydrologic Modeling System (HMS), which is used to forecast floods and droughts.

Forecasting Process

The forecasting process using the Global Forecast System model involves several steps, including data assimilation, model initialization, and model integration. The data assimilation step involves combining the model forecast with the observed data to produce an analysis of the current state of the atmosphere and ocean. The model initialization step involves using the analysis to initialize the model, and the model integration step involves integrating the model forward in time to produce a forecast. The GFS model is typically run four times a day, at 00, 06, 12, and 18 UTC, and provides forecasts for up to 16 days. The GFS model is also used to produce ensemble forecasts, which involve running the model multiple times with different initial conditions to produce a range of possible forecasts. The GFS model is used by meteorologists at the National Weather Service's National Centers for Environmental Prediction and other organizations, such as the European Centre for Medium-Range Weather Forecasts (ECMWF) and the Japan Meteorological Agency (JMA).

Applications and Impact

The Global Forecast System model has a wide range of applications, including weather forecasting, climate forecasting, and research. The GFS model is used to forecast high-impact weather events, such as tornadoes, hurricanes, and blizzards, and is used by emergency management officials to make decisions about evacuations and other emergency response actions. The GFS model is also used to forecast climate variability, such as El Niño and La Niña, and is used by climate researchers to study the climate system. The GFS model has also been used to study the impacts of climate change on weather and climate, in collaboration with the Intergovernmental Panel on Climate Change (IPCC) and the United Nations Environment Programme (UNEP). The GFS model has been used to forecast weather phenomena, such as the 2011 Joplin tornado and Hurricane Sandy, in collaboration with the Federal Emergency Management Agency (FEMA) and the American Red Cross.

Limitations and Future Improvements

The Global Forecast System model has several limitations, including model bias and uncertainty. The model bias refers to the systematic errors in the model, and the uncertainty refers to the random errors in the model. The GFS model also has limitations in terms of its resolution and physics, which can affect its ability to forecast certain types of weather phenomena. To address these limitations, researchers are working to improve the GFS model by developing new physics packages, such as the cloud microphysics scheme, and by increasing the resolution of the model. The GFS model is also being coupled with other models, such as the North American Mesoscale Forecast System (NAM) model, to improve its ability to forecast mesoscale weather phenomena. The GFS model is also being used to study the impacts of climate change on weather and climate, in collaboration with the National Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF).

Category:Meteorology