Helping to predict the weather is the most mature application of Earth observation. Over the last four decades satellites have radically improved the accuracy of weather forecasts. Near-realtime meteorological images are at the heart of daily weather bulletins watched by millions across Europe and the world.
It is estimated that more reliable weather forecasting saves industry and the public millions of Euros every year. The World Meteorological Organisation estimates that every Euro spent on Earth Observation has returned 15 Euros worth of benefit to the agricultural sector alone.
Supercomputers are increasingly at the forefront of weather forecasting, running elaborate numerical models to predict how the meteorological conditions will evolve over the coming hours or days. Ultimately, these models rely on the data they assimilate; the better the quantity and quality of observations they process, the more reliable their final forecast.
Ending blind spots
Satellites allow us to monitor large areas of the globe, compensating for gaps in the terrestrial meteorology data-gathering network. Weather stations and buoys cannot cover the expanse of empty ocean where two thirds of all the precipitation falling on land originates. By contrast, the wide-area view provided by satellites in geostationary orbit can frame an entire weather system in a single optical or infrared image.
Additional space-based instruments routinely provide measurements of climate-related variables such as water vapour and ozone concentrations in the atmosphere plus air and sea-surface temperatures. A radar-based instrument called a scatterometer uses reflected radar pulses to 'see' wind speed and direction across the sea surface.
Meteosat and MetOp
The first operational weather satellite was Tiros 1, launched in 1960. Europe's first weather satellite was Meteosat-1, launched in 1977 and followed by six further first generation Meteosats. This series of geostationary satellites was built by ESA and later operated by the European Organisation for the Exploitation of Meteorological Satellites (Eumetsat), an intergovernmental organisation created in 1986.
In 2002, the existing Meteosats were joined in orbit by the first Meteosat Second Generation (MSG) satellite, a more advanced design that formally entered service as Meteosat-8. Three more MSG satellites followed and the last one, MSG-4, now operating as Meteosat-11, was launched in July 2015.
In October 2006, the Meteosat weather satellites were joined by the first of a brand new generation of meteorological satellites with the launch of MetOp-A. MetOp-A, the first of three satellites developed under a joint programme between ESA and Eumetsat, provides a closer view of the atmosphere from low Earth orbit and delivers data that will improve global weather prediction and enhance our understanding of climate change.
The MetOp programme forms the space segment of Eumetsat's Polar System, EPS, and represents the European contribution to a cooperative venture with the United States’ National Oceanic and Atmospheric Administration (NOAA), which for the last 40 years has been delivering meteorological data from polar orbit.
Responsibilities for the meteorological satellite services are shared between the US and Europe. Three MetOp satellites will ensure the delivery of continuous, high-quality global meteorological data until at least 2020. MetOp-B was launched on 17 September 2012 and MetOp-C completed the first MetOp series in orbit on 7 November 2018.