earth science

Integrated Forecasting System

Integrated Forecasting System is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Integrated Forecasting System rather than just read about it. In short: The Integrated Forecasting System (IFS) is a global numerical weather prediction system jointly developed and maintained by the European Centre for Medium-Range Weather Forecasts (ECMWF) based in Reading, England, and Météo-France based in Toulouse. 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 Global Forecast Sys…

Key takeaways

Integrated Forecasting System belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Integrated Forecasting System to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Integrated Forecasting System from memory before moving on to harder problems.

Reference excerpt

The Integrated Forecasting System (IFS) is a global numerical weather prediction system jointly developed and maintained by the European Centre for Medium-Range Weather Forecasts (ECMWF) based in Reading, England, and Météo-France based in Toulouse. 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 Global Forecast System. Since February 2025, ECMWF has also run a complementary machine-learning-based system, the Artificial Intelligence Forecasting System (AIFS), alongside the physics-based IFS (§ Artificial Intelligence Forecasting System (AIFS)).

Mechanism The IFS 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. With IFS Cycle 50r1 (12 May 2026), the assimilation system became fully coupled across the atmosphere, ocean, and sea ice, allowing the atmospheric model to draw sea surface temperatures directly from the coupled ocean model rather than through the earlier partial-coupling scheme. 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 (GEM and GDPS) and the UK Met Office's Unified Model.

Variants ECMWF runs the IFS in several configurations. Until 2026, the highest-resolution deterministic run ("HRES") was produced separately from the ensemble, but successive cycles merged the two: IFS Cycle 48r1 (27 June 2023) raised the ensemble's horizontal resolution from 18 km to 9 km, matching HRES, Cycle 49r1 (12 November 2024) made the HRES run and the ensemble control member computationally identical, and Cycle 50r1 (12 May 2026) stopped running them separately, producing a single run known as "ENS Control" or "Control forecast". This run is produced four times daily (00Z, 06Z, 12Z, 18Z), with the 00Z/12Z runs extending to 15 days and the 06Z/18Z runs to 6 days, at a horizontal resolution of 9 km using 137 layers in the vertical. The wider 51-member ensemble ("ENS") runs at the same resolution and schedule. Since Cycle 48r1, a separate sub-seasonal range ensemble (renamed from "extended-range" at Cycle 49r1) has run daily from 00 UTC out to 46 days with 101 members, at 36 km horizontal resolution and 137 vertical layers. ECMWF also produces seasonal forecasts through SEAS5, operational since 5 November 2017. SEAS5 runs as a 51-member ensemble at 36 km resolution out to 7 months, and is extended four times a year to a 13-month "annual-range" forecast using a 15-member subset.

Artificial Intelligence Forecasting System (AIFS) Since 2025, ECMWF has run a parallel machine-learning-based forecasting system alongside the physics-based IFS: the Artificial Intelligence/Integrated Forecasting System (AIFS), named as a nod to the IFS itself. AIFS is a data-driven model built on a graph neural network encoder and decoder with a transformer-based processor, developed with ECMWF's Anemoi toolkit and trained on the ERA5 reanalysis together with operational IFS analyses. The deterministic version, AIFS Single, has run operationally since 25 February 2025 — the first operational use of a global data-driven forecasting model at a major international weather centre — generating a complete 15-day forecast within minutes on ECMWF's computing infrastructure. An ensemble version, AIFS ENS, has run operationally since 1 July 2025. Both were upgraded to version 2 alongside IFS Cycle 50r1 on 12 May 2026, adding ECMWF's first data-driven wave and snow-cover forecasts.

Usage Many ECMWF member states use ECMWF global forecasts to provide boundary conditions for their own higher resolution, limited domain forecasts. ECMWF forecasts remain free to the national weather services of its member states. Public access to ECMWF's real-time forecast data has broadened substantially since the early 2020s: following a phased transition approved by the ECMWF Council in December 2020, ECMWF reached full open-data status on 1 October 2025, and its entire Real-time Catalogue — covering both IFS and AIFS output — is now licensed under Creative Commons Attribution 4.0 (CC-BY-4.0), permitting reuse, redistribution, and commercial use subject to attribution. A free subset is published at 25 km resolution with no cost; access to the full higher-resolution catalogue (down to 9 km) may still involve delivery or service charges to cover distribution costs, rather than a licensing fee. This replaced ECMWF's earlier model, under which limited public data was available only under a more restrictive non-commercial, no-derivatives licence (CC-BY-ND-NC). The full IFS source code — including its data assimilation system — remains available only to the national weather services of ECMWF member states. The OpenIFS project, a version of the forecast model without the data assimilation system, was previously available only under a bespoke, non-open-source licence from ECMWF, but was made fully open source under the Apache 2.0 licence on 5 March 2026 and published on GitHub. The EC-Earth climate model is based on the IFS.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Integrated Forecasting System

Start with the simplest possible case. Write down what Integrated Forecasting System claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Integrated Forecasting System before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Integrated Forecasting System ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Integrated Forecasting System

In research: Integrated Forecasting System appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Integrated Forecasting System in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Integrated Forecasting System is common in secondary-school and first-year university syllabi. It links to neighbouring topics ECWMF numerical models, Weather prediction, so understanding it makes those chapters shorter.
In everyday life: Look for Integrated Forecasting System outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Integrated Forecasting System in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Integrated Forecasting System means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Integrated Forecasting System out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Integrated Forecasting System in simple terms?

Why does Integrated Forecasting System matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Integrated Forecasting System?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Integrated Forecasting System.