The Integrated Forecasting System (IFS) is a global
numerical weather prediction
Numerical weather prediction (NWP) uses mathematical models of the atmosphere and oceans to predict the weather based on current weather conditions. Though first attempted in the 1920s, it was not until the advent of computer simulation in th ...
system jointly developed and maintained by the
European Centre for Medium-Range Weather Forecasts
The European Centre for Medium-Range Weather Forecasts (ECMWF) is an independent intergovernmental organisation supported by most of the nations of Europe. It is based at three sites: Shinfield Park, Reading, United Kingdom; Bologna, Italy; an ...
(ECMWF) based in
Reading, England, and
Météo-France based in
Toulouse
Toulouse ( , ; oc, Tolosa ) is the prefecture of the French department of Haute-Garonne and of the larger region of Occitania. The city is on the banks of the River Garonne, from the Mediterranean Sea, from the Atlantic Ocean and from Pa ...
.
The version of the IFS run at ECMWF is often referred to as the "ECMWF" or the "European model" in North America, to distinguish it from the American GFS.
Mechanism
It comprises a
spectral atmospheric model with a
terrain-following vertical coordinate system coupled to a
4D-Var data assimilation system. In 1997 the IFS became the first operational forecasting system to use 4D-Var. Both ECMWF and Météo-France use the IFS to make operational weather forecasts, but using a different configuration and resolution (the Météo-France configuration is referred to as ARPEGE). It is one of the predominant global medium-range models in general use worldwide; its most prominent rivals in the 6–10 day medium range include the American
Global Forecast System (GFS), the Canadian
Global Environmental Multiscale Model
The Global Environmental Multiscale Model (GEM), often known as the CMC model in North America, is an integrated forecasting and data assimilation system developed in the Recherche en Prévision Numérique (RPN), Meteorological Research Branch (MRB ...
(GEM and GDPS) and the
UK Met Office Unified Model The Unified Model is a numerical weather prediction and climate modeling software suite originally developed by the United Kingdom Met Office, and now both used and further developed by many weather-forecasting agencies around the world. The Unif ...
.
Variants
ECMWF runs the IFS in several configurations. The highest resolution "HRES" configuration is run every 6 hours (00Z and 12Z out to 10 days, 06Z/18Z out to 90 hours) with a horizontal resolution of 9 km using 137 layers in the vertical. The 51-member ensemble system "ENS" is also run every twelve hours out to 15 days and every 06Z/18Z out to 6 days with a horizontal resolution of 18 km and 137 layers in the vertical. The ECMWF also runs a coarser version of the IFS out 45 days; this version is run weekly, with output in five-day intervals. There is also a version that runs out one year. All model versions except HRES are coupled to the
ocean model NEMO.
Usage
Many ECMWF member states use ECMWF global forecasts to provide boundary conditions for their own higher resolution, limited domain forecasts. ECMWF forecasts are free to the national weather services of its member states, but a fee is charged to commercial users, while limited operational data (select variables from the HRES and ENS out ten days) is available direct to consumers under the noncommercial
Creative Commons license
A Creative Commons (CC) license is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted "work".A "work" is any creative material made by a person. A painting, a graphic, a book, a song/lyric ...
prohibiting
derivative works (CC-BY ND NC). In contrast, output from the GFS and GEM/GDPS is freely licensed to all users.
The full IFS
source code
In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the w ...
is available only to the national weather services of ECMWF member states,
[. The source code for the atmosphere model is available to other non-commercial users in the form of the OpenIFS which requires a free license. The EC-Earth ]climate model
Numerical climate models use quantitative methods to simulate the interactions of the important drivers of climate, including atmosphere, oceans, land surface and ice. They are used for a variety of purposes from study of the dynamics of the c ...
is based on the IFS.
References
External links
ECMWF research page
Changes in the ECMWF model
ARPEGE-IFS
IFS documentation
Numerical climate and weather models
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