Public Release: 

European Centre for Medium-Range Weather Forecasts - Model upgraded to best ever

ECMWF

  • More accurate global weather predictions at record-breaking resolution
  • Number of grid points tripled to 900 million, evenly distributed around the globe
  • Gain in predictability of up to half a day at same level of quality

Years of scientific and technical work came to fruition today as the European Centre for Medium-Range Weather Forecasts (ECMWF) launched a significant set of upgrades, dramatically increasing the quality of both its high-resolution and its ensemble forecasts.

The changes nearly halve the distance between global weather prediction points, substantially increasing the effective resolution of the final forecast. As a result, ECMWF's numerical weather predictions, which are widely used by Europe's meteorological services, are more accurate than they have ever been before.

These model upgrades represent a huge leap forward for ECMWF's 34 Member and Co-operating States, giving National Meteorological Services access to higher resolution and improved data to help them deliver weather forecast services. Europe's weather can now be predicted with more detail, with greater accuracy, and as a result, up to half a day further ahead.

The upgrades are set to offer improved range, reliability and accuracy to provide earlier warnings of adverse conditions and extreme weather to help protect property and vital infrastructure, and to aid long-term planning for weather-dependent industries.

Speaking for Meteo-France, Nicole Girardot commented:

"The ECMWF upgrade to its model resolution represents a significant step. The advances brought by this new version will allow Meteo-France to improve the quality of its own forecasts and the wind forcing for warnings of poor air quality and dangerous conditions at sea. It will also more specifically help with the prediction of extreme and severe weather in French overseas territories: better estimates of cyclonic phenomena, at medium-range and monthly timescales, and the provision of coupling data for the French Arome model run at very high resolution in these regions."

These upgrades are taking place at several levels of the numerical prediction process, all leading to a substantial improvement in the accuracy of ECMWF forecasts.

One of the main changes - one of only a handful of its kind in 40 years of European weather cooperation - increases the number of global points where a weather prediction is made to more than 900 million. This reduces the average distance between points from 16 km to 9 km in the highest-resolution forecasts. Ensemble forecasts describing the range of possible scenarios and their likelihood are moving from 32 and 64 to 18 km up to forecast day 15. There are up to 137 layers of these prediction points, forming a network of grid points from near the Earth's surface up to the stratosphere.

As well as the resolution upgrade, the new cycle includes many improvements to the assimilation of observations making it possible to extract more valuable information from data. There is also extended observation coverage: microwave data is being used in more challenging situations such as mountain areas and snow-covered land surfaces, and the coverage of satellite-derived winds is being improved in the mid-latitudes. These improvements lead to a better assessment of the current state of the atmosphere and improved forecast quality.

A further change arranges the prediction points so they are distributed more efficiently across the Earth's surface, saving computing time. The pattern is built up starting from an octahedron enclosing the globe, giving rise to an 'octahedral grid'. Further substantial efficiency gains have been made in the processing of observations and other areas, making the task of continually improving the weather forecast more sustainable.

ECMWF Director-General Florence Rabier said:

"The impact of the weather and its potentially deadly extremes is one of the key challenges facing emergency response services, policymakers, and industry. This makes the role of the National Meteorological Services that we serve critical to society.

"Our ability to predict the weather accurately has in the past improved by around 24 hours every ten years, so this jump of up to twelve hours is a big step forward.

"These upgrades launched today not only increase the detail of our global operational forecast, its range and accuracy, but do so in a sustainable way, clearing the way for further improvement. This was only achievable through the work ECMWF and its partners are conducting in the field of coding and computing efficiency.

"By continuing to drive improvements in global numerical weather prediction, ECMWF is contributing to Europe's resilience and sustainability."

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Notes to editors:

1. ECMWF is an intergovernmental organisation supported by 34 European States. It provides weather services with medium-range forecasts of global weather to 15 days ahead as well as with monthly and seasonal forecasts. ECMWF's computer system at its headquarters in Reading, United Kingdom, is one of the largest for meteorology worldwide and contains the world's largest archive of numerical weather prediction data. It runs a sophisticated medium-range prediction model of the global atmosphere and oceans. The National Meteorological Services of Member States and Co-operating States use ECMWF's products for their own national duties, in particular to give early warning of potentially damaging severe weather.

2. More available at http://www.ecmwf.int

3. The upgrades to the forecast model will give 34 National Meteorological Services access to higher resolution and improved data to help them deliver improved weather forecast services. These are:

Member States:

  • Austria, Zentralanstalt fur Meteorologie und Geodynamik (ZAMG)
  • Belgium, Royal Meteorological Institute of Belgium (RMI/KMI)
  • Croatia, Meteorological and Hydrological Service of Croatia (DHMZ)
  • Denmark, Danmarks Meteorologiske Institut (DMI)
  • Finland, Ilmatieteen Laitos / Finnish Meteorological Institute (FMI)
  • France, Météo-France
  • Germany, Deutscher Wetterdienst (DWD)
  • Greece, Hellenic National Meteorological Service (HNMS)
  • Iceland, Icelandic Meteorological Office (IMO)
  • Ireland, Met &Eireann
  • Italy, Stato Maggiore Aeronautica, Ufficio Generale Spazio Aereo e Meteorologia (USAM)
  • Luxembourg, Service Meteorologique - MeteoLux, Administration de la navigation aerienne
  • Netherlands, Royal Netherlands Meteorological Institute / Koninklijk Nederlands Meteorologisch Instituut (KNMI)
  • Norway, Meteorologisk Institutt / Norwegian Meteorological Institute
  • Portugal, Instituto Portugues do Mar e da Atmosfera (IPMA)
  • Serbia, Republicki Hidrometeoroloski Zavod Srbije / Republic Hydrometeorological Service of Serbia
  • Slovenia, Meteorological Office, Slovenian Environment Agency (SEA)
  • Spain, Agencia Estatal de Meteorologia / State Meteorological Agency (AEMET)
  • Sweden, Vader Vaderprognoser Klimat- & Vadertjanster i Sverige/Swedish Meteorological and Hydrological Institute (SMHI)
  • Switzerland, Federal Office of Meteorology and Climatology MeteoSwiss
  • Turkey, Meteoroloji Genel Mudurlugu
  • United Kingdom, Met Office

Co-operating States:

  • Bulgaria, National Institute of Meteorology and Hydrology
  • Czech Republic, Czech Hydrometeorological Institute (CHMI)
  • Estonia, Estonian Environment Agency
  • Former Yugoslav Republic of Macedonia, National Hydrological Institute of Macedonia
  • Hungary, Hungarian Meteorological Service (HMS)
  • Israel, Israel Meteorological Service
  • Latvia, Latvian Environmental, Geological and Meteorological Centre
  • Lithuania, Lithuanian Hydrometeorological Service
  • Montenegro, Institute of Hydrometeorology and Seismology of Montenegro (IHMS)
  • Morocco, Meteorologie Nationale, Royaume du Maroc
  • Romania, National Meteorological Administration
  • Slovakia, Slovensky hydrometeorologicky ustavv / Slovak Hydrometeorological Institute (SHMU)

FAQ

INTRODUCING 41R2: MOST ACCURATE AND HIGHEST-EVER RESOLUTION IN GLOBAL NUMERICAL WEATHER PREDICTION.

1. Statement and key messages

What has been announced today?

We're announcing a significant set of upgrades launched by the European Centre for Medium Range Weather Forecasts (ECMWF). The changes nearly halve the distance between global weather prediction points, substantially increasing the effective resolution of the forecast. As a result, ECMWF's numerical weather predictions, which are widely used by Europe's meteorological services, are more accurate, contain three times as much detail and can predict the weather up to half a day further ahead.

Key messages

  • Most accurate global weather predictions at record-breaking resolution.
  • Number of grid points tripled to 900 million in the high-resolution forecast, evenly distributed around the globe.
  • Gain in predictability of up to half a day at same level of quality.

2. Changes

What are the main changes?

  • ECMWF has tripled the number of global points where a weather prediction is made to more than 900 million for the highest-resolution forecast. This reduces the distance between points from 16 km to 9 km, bringing a substantial increase in horizontal resolution.
  • Ensemble forecasts describing the range of possible scenarios and the likelihood of occurrence are now at 18 km up to forecast day 15 and 36 km thereafter, down from 32 km up to forecast day 10 and 64 km thereafter.
  • ECMWF has changed the way the grid points are laid out across the globe so they are distributed more uniformly. This is referred to as an 'octahedral grid' after the shape used to determine the grid's layout.
  • ECMWF has improved the computation efficiency of the calculations used to determine the weather prediction at each grid point.
  • The analysis and ensemble of analyses - which enable a flow-dependent estimation of the weights to be given to the observations - see their resolution increasing substantially too, contributing to the improvements of the high-resolution initial conditions and forecasts.

Further changes

There are also a host of further upgrades, leading to a better analysis of the atmospheric state and to improved forecast quality. These include:

  • More scales in predictions and a better description of land-sea contrasts and mountains.
  • Changes to the observation error representation for GPS radio occultation and microwave data.
  • Improved screening, such as a better identification of aerosol contamination in the infrared and an upgrade for the microwave part of the observation operator.
  • Extended observation coverage, for example microwave data is being used in more challenging situations such as mountain areas and snow-covered land surfaces, and coverage of satellite-derived winds is being improved in the mid-latitudes.

Why are these changes significant?

This is a major upgrade, and one of only a handful of horizontal resolution upgrades in 40 years of European cooperation on weather forecasting. It extends the range of forecasts at the same level of quality by several hours for many parameters. For example, ECMWF's high-resolution 10-metre wind speed forecast in Europe will see its range improved by as much as half a day up to forecast day 5. In particular, the changes promise significant improvements in the prediction of severe weather events.

Will vertical resolution also be increased?

No, this will be maintained at 137 levels for the highest-resolution forecasts, and at 91 levels for the ensemble forecasts.

3. Benefits

What difference will this make?

This change means Europe's weather can now be predicted with improved accuracy, with three times as much detail and up to half a day further ahead. The upgrade will:

  • Allow our members to support improved long-term planning for weather-dependent industries.
  • Provide the potential for earlier warning of adverse conditions and extreme weather to help protect property and vital infrastructure.
  • Make the calculations made by ECMWF's supercomputers to obtain predictions more efficient, saving energy and money to help make the task of continually improving the weather forecast more sustainable.

Who will benefit from the improved resolution?

ECMWF supplies forecasts and analyses to 34 Member and Co-operating States. The upgrade will give their National Meteorological Services access to higher-resolution products to help them deliver weather forecast services.

4. Explanation of terms

What does higher resolution and more accuracy mean in practice?

It means that in the highest-resolution forecasts each area where ECMWF predicts the weather across the globe is now a third of the size it was before - 77 km2 rather than 238 km2 - and ECMWF can make a longer-range high-quality weather prediction. This means that across any region we can now tell what the weather will be in three times as much detail, further into the future.

What is an ensemble forecast?

Since 1992, ECMWF has pioneered ensemble forecasts, which describe the range of scenarios and the likelihood of occurrence. Running the forecast 52 times starting from slightly different initial states generates a spread which describes the possible forecasts on that particular day. ECMWF believes that an ensemble approach is essential due to the inherent forecast uncertainty and the need to adequately capture the likelihood of extreme weather because of its potentially disastrous consequences.

5. ECMWF and partners - roles and responsibilities

What is ECMWF?

The European Centre for Medium-Range Weather Forecasts (ECMWF) is an independent intergovernmental organisation supported by 34 states. ECMWF is both a research institute and a 24/7 operational service, producing and disseminating global numerical weather predictions to its Member States.

What is its role?

ECMWF's role is to address the most difficult research problems in numerical weather prediction that no one country can tackle on its own, so that all can improve the range and accuracy of their forecasts. Introducing the new grid is one such example. ECMWF have been working with Member States for a number of years to introduce the change.

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