Monitoring Weather

Reliable weather forecasts are key to our safety and our economy. To help save lives and reduce damage to property and infrastructure from storms, heavy precipitation, heat waves and tropical cyclones – as well as other hazards influenced by weather, like floods or dispersion of atmospheric or marine pollution – European citizens and decision-makers require timely warnings from their National Meteorological Services, which are based on forecasts.

Furthermore, over a third of the European economy is weather-sensitive and requires accurate forecasts for business purposes. This is particularly true for energy, transportation, construction, agriculture, tourism and utilities. Energy providers, for example, rely on weather forecasts to anticipate power demand and adapt their production during both hot and cold spells. With the development of renewable energy, production itself will increasingly depend on the weather.

Likewise, forecasts of fog, snow, high winds, thunderstorms and weather-induced dispersion of ash particles are critical to aviation and air-traffic management, and by extension to the global economy.

Accurate weather predictions start from the best possible knowledge of the initial state of the Earth's atmosphere, which is built using frequent, global observations of the atmosphere and the underlying surfaces. The observations from satellites are a prominent source, and have become indispensible for forecasting the weather at all ranges, contributing to the downstream production of warnings and other information that support our continued social and economic wellbeing.
 

METEOSAT imagery used in "NOWCASTING" of high impact weather

To issue warnings on the most rapidly developing weather phenomena, forecasters execute a challenging task called "nowcasting". Nowcasting is about real-time detection of rapidly developing situations in high-impact weather, and then predicting their evolution a few hours ahead.

Nowcasting requires a constant pipeline of frequent, high-quality images of the atmosphere as captured and delivered in real-time. Geostationary weather satellites like Meteosat have the unique capability to deliver repetitive real time imagery from 36,000 km above the Earth's surface, every 5 to 15 minutes or even less, and are therefore a vital source of input data.

The current Meteosat system, built around Meteosat Second Generation (MSG) satellites and their main instrument SEVIRI, is capable of scanning a full disc image of the Earth in 15 minutes or Europe within 5 minutes, when used in Rapid Scanning Service (RSS) mode. EUMETSAT simultaneously exploits two Meteosat Second Generation satellites to deliver both the full disc imagery and the rapid scan service over Europe.
 

The EUMETSAT Polar System: A closer, global view from the polar orbit

The Metop satellites form the space segment of the EUMETSAT Polar System (EPS), flying in polar orbit at an altitude of approximately 817 km, about 42 times closer to the Earth than a geostationary satellite.

Thus, they provide a unique wealth of observations about ocean, land and atmospheric parameters that can only be measured from such low altitude orbits. Metop delivers data much less frequently than Meteosat, but provides global and quantitative observations which are the most critical inputs to the numerical models used to forecast weather up to 10 days in advance.

Recent studies confirm that Metop makes a major contribution to the performance of Numerical Weather Prediction (NWP), accounting for 25% of the reduction of 24 hour forecast errors due to all observations ingested in real time by models. Because of this high contribution to the reduction of forecast errors, a significant portion of the high socio-economic benefits of weather forecasting – estimated at €61.4 billion per year in the European Union – can be attributed to Metop satellites to the order of €4.9 billion per year.