ECMWF Model Upgrade Improves Extended-Range Weather Forecasts

PR73866

READING, England, June 6, 2018, /PRNewswire=KYODO JBN/--

A wide-ranging upgrade of ECMWF's Integrated Forecasting System (IFS),

implemented on 5 June 2018, brings better global weather forecasts, with

particularly consistent gains in the extended range. A key plank of the upgrade

is enhanced dynamic coupling between the ocean, sea ice and the atmosphere.

The upgrade:

-  improves forecast quality in the tropics, enabling better predictions in the

extended range in Europe and elsewhere, notably at weeks three and four

-  improves 2-metre temperature forecasts, including in Europe

-  brings better predictions of rain in coastal areas as a result of improved

cloud physics

-  improves high-resolution forecasts in situations marked by rapid

interactions between sea ice, the ocean and the atmosphere, such as the passage

of tropical cyclones or rapid changes in sea ice cover

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Up to now, dynamic ocean, sea ice and atmosphere coupling has only been applied

in medium-range ensemble forecasts (18 km horizontal resolution),

extended-range forecasts and seasonal forecasts. The upgrade extends this

coupling to ECMWF's medium-range high-resolution forecasts (9 km horizontal

resolution). In addition, the upgrade enhances coupling in the tropics for both

high-resolution and ensemble forecasts. As a result, the IFS is now more

consistent and seamless across different timescales and spatial resolutions.

Other changes include:

a better use of observations, notably through a scheme to account for the

horizontal drift of radiosondes during their ascent

the use of more satellite observations, including non-surface-sensitive

infrared channels over land

more realistic ocean depth (bathymetry), which mostly affects the wave fields

in coastal areas

the introduction of new products useful in the prediction of severe weather,

including forecasts of lightning flash density, and of maximum convective

available potential energy (CAPE) over the last six hours of the forecast.

The changes are based on research by scientists at the Centre, often in

collaboration with other scientists in ECMWF's Member States and beyond.

Accounting for the drift of radiosondes has notably been made possible by a new

data format providing full position information that is being rolled out across

the world.

Director of Forecasts Florian Pappenberger said: "The new model version brings

pronounced improvements in upper-air predictions in the tropics, especially for

wind and temperature. It is exciting to see the consistent gains in

extended-range forecasts and the overall improvement in 2-metre temperature

both in high-resolution and ensemble forecasts, particularly for Europe. In

addition, near-coastal precipitation in warm-rain dominated situations is

significantly improved, addressing a long-standing issue with our model."

Director of Research Andy Brown said: "This is a substantial upgrade which

marks a milestone towards our Strategy to 2025. The Strategy calls for a more

seamless forecasting system by making our different forecasts more coherent.

The enhanced coupling across all time ranges brings us one step closer to

seamlessness. In addition to the important immediate benefits the upgrade

delivers, it prepares the ground for further sustained progress."

Notes for editors

The European Centre for Medium-Range Weather Forecasts (ECMWF) is an

independent intergovernmental organisation supported by 34 states, established

in 1975. ECMWF's core mission is to produce numerical weather forecasts, carry

out scientific and technical research to improve forecast skill, and to

maintain an archive of meteorological data.

For more details, please see:

https://www.ecmwf.int/en/about/media-centre/news/2018/ifs-upgrade-improves-extended-range-weather-forecasts

For more information, please contact: ECMWF Press Office, +44-118-949-9000,

pressoffice@ecmwf.int

Source: European Centre for Medium-Range Weather Forecasts